tcsh —
C shell
with file name completion and command line editing
tcsh |
[-bcdefFimnqstvVxX]
[-Dname[=value]]
[arg] ... |
tcsh is an enhanced but completely compatible
version of the Berkeley UNIX C shell,
csh(1). It
is a command language interpreter usable both as an interactive login shell
and a shell script command processor. It includes a command-line editor (see
The command-line
editor (+)), programmable word completion (see
Completion and
listing (+)), spelling correction (see
Spelling correction
(+)), a history mechanism (see
History
substitution), job control (see
Jobs) and a C-like syntax. The
NEW FEATURES (+) section
describes major enhancements of
tcsh over
csh(1). Throughout this manual, features of
tcsh not found in most
csh(1) implementations (specifically, the 4.4BSD
csh(1)) are labeled with ‘(+)’, and
features which are present in
csh(1) but not
usually documented are labeled with ‘(u)’.
If the first argument (argument 0) to the shell is
‘
-
’ then it is a login shell. A login
shell can be also specified by invoking the shell with the
-l flag as the only argument.
The rest of the flag arguments are interpreted as follows:
- -b
- Forces a “break” from option processing,
causing any further shell arguments to be treated as non-option arguments.
The remaining arguments will not be interpreted as shell options. This may
be used to pass options to a shell script without confusion or possible
subterfuge. The shell will not run a set-user ID script without this
option.
- -c
- Commands are read from the following argument (which must
be present, and must be a single argument), stored in the
command shell variable for reference, and
executed. Any remaining arguments are placed in the
argv shell variable.
- -d
- The shell loads the directory stack from
~/.cshdirs as described under
Startup and
shutdown, whether or not it is a login shell. (+)
-
-Dname[=value]
- Sets the environment variable
name to
value. (Domain/OS only) (+)
- -e
- The shell exits if any invoked command terminates
abnormally or yields a non-zero exit status.
- -f
- The shell does not load any resource or startup files, or
perform any command hashing, and thus starts faster.
- -F
- The shell uses fork(2) instead
of vfork(2) to spawn processes. (+)
- -i
- The shell is interactive and prompts for its top-level
input, even if it appears to not be a terminal. Shells are interactive
without this option if their inputs and outputs are terminals.
- -l
- The shell is a login shell. Applicable only if
-l is the only flag specified.
- -m
- The shell loads ~/.tcshrc even
if it does not belong to the effective user. Newer versions of
su(1) can pass
-m to the shell. (+)
- -n
- The shell parses commands but does not execute them. This
aids in debugging shell scripts.
- -q
- The shell accepts SIGQUIT (see
Signal handling) and
behaves when it is used under a debugger. Job control is disabled.
(u)
- -s
- Command input is taken from the standard input.
- -t
- The shell reads and executes a single line of input. A
‘
\
’ may be used to escape the
newline at the end of this line and continue onto another line.
- -v
- Sets the verbose shell
variable, so that command input is echoed after history substitution.
- -x
- Sets the echo shell variable,
so that commands are echoed immediately before execution.
- -V
- Sets the verbose shell
variable even before executing
~/.tcshrc.
- -X
- Is to -x as
-V is to
-v.
- --help
- Print a help message on the standard output and exit.
(+)
- --version
- Print the version/platform/compilation options on the
standard output and exit. This information is also contained in the
version shell variable. (+)
After processing of flag arguments, if arguments remain but none of the
-c,
-i,
-s, or
-t options
were given, the first argument is taken as the name of a file of commands, or
“script”, to be executed. The shell opens this file and saves
its name for possible resubstitution by
‘
$0
’. Because many systems use either
the standard version 6 or version 7 shells whose shell scripts are not
compatible with this shell, the shell uses such a “standard”
shell to execute a script whose first character is not a
‘
#
’, i.e., that does not start with a
comment.
Remaining arguments are placed in the
argv shell
variable.
A login shell begins by executing commands from the system files
/etc/csh.cshrc and
/etc/csh.login. It then executes commands from
files in the user's
home directory: first
~/.tcshrc (+) or, if
~/.tcshrc is not found,
~/.cshrc, then the contents of
~/.history (or the value of the
histfile shell variable) are loaded into memory,
then
~/.login, and finally
~/.cshdirs (or the value of the
dirsfile shell variable) (+). The shell may read
/etc/csh.login before instead of after
/etc/csh.cshrc, and
~/.login before instead of after
~/.tcshrc or
~/.cshrc and
~/.history, if so compiled; see the
version shell variable. (+)
Non-login shells read only
/etc/csh.cshrc and
~/.tcshrc or
~/.cshrc on startup.
For examples of startup files, please consult:
http://tcshrc.sourceforge.net
Commands like
stty(1) and
tset(1), which need be run only once per login,
usually go in one's
~/.login file. Users who need
to use the same set of files with both
csh(1) and
tcsh can have only a
~/.cshrc which checks for the existence of the
tcsh shell variable before using
tcsh-specific commands, or can have both a
~/.cshrc and a
~/.tcshrc which
sources (see the builtin command)
~/.cshrc. The rest of this manual uses
~/.tcshrc to mean
~/.tcshrc or, if
~/.tcshrc is not found,
~/.cshrc.
In the normal case, the shell begins reading commands from the terminal,
prompting with
>
(Processing of arguments and the use of the shell to process files containing
command scripts are described later.) The shell repeatedly reads a line of
command input, breaks it into words, places it on the command history list,
parses it and executes each command in the line.
One can log out by typing
^D on an empty line,
logout or
login or
via the shell's autologout mechanism (see the
autologout shell variable). When a login shell
terminates it sets the
logout shell variable to
‘
normal
’ or
‘
automatic
’ as appropriate, then
executes commands from the files
/etc/csh.logout
and
~/.logout. The shell may drop DTR on logout
if so compiled; see the
version shell variable.
The names of the system login and logout files vary from system to system for
compatibility with different
csh(1) variants; see
FILES.
We first describe
The command-line
editor (+). The
Completion and
listing (+) and
Spelling correction
(+) sections describe two sets of functionality that are implemented as
editor commands but which deserve their own treatment. Finally,
Editor commands (+)
lists and describes the editor commands specific to the shell and their
default bindings.
Command-line input can be edited using key sequences much like those used in
emacs(1) or
vi(1).
The editor is active only when the
edit shell
variable is set, which it is by default in interactive shells. The
bindkey builtin can display and change key
bindings to editor commands (see
Editor commands (+)).
emacs(1)-style key bindings are used by default
(unless the shell was compiled otherwise; see the
version shell variable), but
bindkey can change the key bindings to
vi(1)-style bindings en masse.
The shell always binds the arrow keys (as defined in the
TERMCAP
environment variable) to editor
commands:
unless doing so would alter another single-character binding. One can set the
arrow key escape sequences to the empty string with
settc to prevent these bindings. The ANSI/VT100
sequences for arrow keys are always bound.
Other key bindings are, for the most part, what
emacs(1) and
vi(1)
users would expect and can easily be displayed by
bindkey, so there is no need to list them here.
Likewise,
bindkey can list the editor commands
with a short description of each. Certain key bindings have different behavior
depending if
emacs(1) or
vi(1)-style bindings are being used; see
vimode for more information.
Note that editor commands do not have the same notion of a “word”
as does the shell. The editor delimits words with any non-alphanumeric
characters not in the shell variable
wordchars,
while the shell recognizes only whitespace and some of the characters with
special meanings to it, listed under
Lexical structure.
The shell is often able to complete words when given a unique abbreviation. For
example, typing part of a word
ls /usr/lost
and hit the tab key to run the
complete-word editor
command. The shell completes the filename
/usr/lost to
/usr/lost+found/, replacing the incomplete word
with the complete word in the input buffer. (Note the terminal
‘
/’; completion adds a
‘
/
’ to the end of completed directories
and a space to the end of other completed words, to speed typing and provide a
visual indicator of successful completion. The
addsuffix shell variable can be unset to prevent
this.) If no match is found (perhaps
/usr/lost+found doesn't exist), the terminal bell
rings. If the word is already complete (perhaps there is a
/usr/lost on your system, or perhaps you were
thinking too far ahead and typed the whole thing) a
‘
/
’ or space is added to the end if it
isn't already there.
Completion works anywhere in the line, not at just the end; completed text
pushes the rest of the line to the right. Completion in the middle of a word
often results in leftover characters to the right of the cursor that need to
be deleted.
Commands and variables can be completed in much the same way. For example,
typing
em[tab]
would complete ‘
em
’ to
‘
emacs
’ if
‘
emacs
’ were the only command on your
system beginning with ‘
em
’. Completion
can find a command in any directory in
path or if
given a full pathname.
Typing
echo $ar[tab]
would complete ‘
$ar
’ to
‘
$argv
’ if no other variable began with
‘
ar
’.
The shell parses the input buffer to determine whether the word you want to
complete should be completed as a filename, command or variable. The first
word in the buffer and the first word following
‘
;
’,
‘
|
’,
‘
|&
’,
‘
&&
’, or
‘
||
’ is considered to be a command. A
word beginning with ‘
$
’ is considered to
be a variable. Anything else is a filename. An empty line is
“completed” as a filename.
You can list the possible completions of a word at any time by typing
^D to run the
delete-char-or-list-or-eof editor command. The
shell lists the possible completions using the
ls-F builtin and reprints the prompt and
unfinished command line, for example:
> ls /usr/l[^D]
lbin/ lib/ local/ lost+found/
> ls /usr/l
If the
autolist shell variable is set, the shell
lists the remaining choices (if any) whenever completion fails:
> set autolist
> nm /usr/lib/libt[tab]
libtermcap.a@ libtermlib.a@
> nm /usr/lib/libterm
If the
autolist shell variable is set to
‘
ambiguous
’, choices are listed only
when completion fails and adds no new characters to the word being completed.
A filename to be completed can contain variables, your own or others' home
directories abbreviated with ‘
~
’ (see
Filename
substitution) and directory stack entries abbreviated with
‘
=
’ (see
Directory
stack substitution (+)). For example,
> ls ~k[^D]
kahn kas kellogg
> ls ~ke[tab]
> ls ~kellogg/
or
> set local = /usr/local
> ls $lo[tab]
> ls $local/[^D]
bin/ etc/ lib/ man/ src/
> ls $local/
Note that variables can also be expanded explicitly with the
expand-variables editor command.
delete-char-or-list-or-eof lists at only the end of
the line; in the middle of a line it deletes the character under the cursor
and on an empty line it logs one out or, if the
ignoreeof variable is set, does nothing.
M-^D, bound to the editor command
list-choices, lists completion possibilities
anywhere on a line, and
list-choices (or any one
of the related editor commands that do or don't delete, list and/or log out,
listed under
delete-char-or-list-or-eof) can be
bound to
^D with the
bindkey builtin command if so desired.
The
complete-word-fwd and
complete-word-back editor commands (not bound to
any keys by default) can be used to cycle up and down through the list of
possible completions, replacing the current word with the next or previous
word in the list.
The shell variable
fignore can be set to a list of
suffixes to be ignored by completion. Consider the following:
> ls
Makefile condiments.h~ main.o side.c
README main.c meal side.o
condiments.h main.c~
> set fignore = (.o \~)
> emacs ma[^D]
main.c main.c~ main.o
> emacs ma[tab]
> emacs main.c
‘
main.c~
’ and
‘
main.o
’ are ignored by completion (but
not listing), because they end in suffixes in
fignore. Note that a
‘
\
’ was needed in front of
‘
~
’ to prevent it from being expanded to
home as described under
Filename
substitution.
fignore is ignored if only one
completion is possible.
If the
complete shell variable is set to
‘
enhance
’, completion 1) ignores case
and 2) considers periods, hyphens and underscores
(‘
.
’,
‘
-
’, and
‘
_
’) to be word separators and hyphens
and underscores to be equivalent. If you had the following files
comp.lang.c comp.lang.perl comp.std.c++
comp.lang.c++ comp.std.c
and typed
mail -f c.l.c[tab]
it would be completed to
mail -f comp.lang.c
and typing
mail -f c.l.c[^D]
would list ‘
comp.lang.c
’ and
‘
comp.lang.c++
’.
Typing
mail -f c..c++[^D]
would list ‘
comp.lang.c++
’ and
‘
comp.std.c++
’.
Typing
rm a--file[^D]
in the following directory
A_silly_file a-hyphenated-file another_silly_file
would list all three files, because case is ignored and hyphens and underscores
are equivalent. Periods, however, are not equivalent to hyphens or
underscores.
If the
complete shell variable is set to
‘
Enhance
’, completion ignores case and
differences between a hyphen and an underscore word separator only when the
user types a lowercase character or a hyphen. Entering an uppercase character
or an underscore will not match the corresponding lowercase character or
hyphen word separator.
Typing
rm a--file[^D]
in the directory of the previous example would still list all three files, but
typing
rm A--file
would match only ‘
A_silly_file
’ and typing
rm a__file[^D]
would match just ‘
A_silly_file
’ and
‘
another_silly_file
’ because the user
explicitly used an uppercase or an underscore character.
Completion and listing are affected by several other shell variables:
recexact can be set to complete on the shortest
possible unique match, even if more typing might result in a longer match:
> ls
fodder foo food foonly
> set recexact
> rm fo[tab]
just beeps, because ‘
fo
’ could expand to
‘
fod
’ or
‘
foo
’, but if we type another
‘
o
’,
the completion completes on ‘
foo
’, even
though ‘
food
’ and
‘
foonly
’ also match.
autoexpand can be set to run the
expand-history editor command before each
completion attempt,
autocorrect can be set to
spelling-correct the word to be completed (see
Spelling correction
(+)) before each completion attempt and
correct can be set to complete commands
automatically after one hits return.
matchbeep
can be set to make completion beep or not beep in a variety of situations, and
nobeep can be set to never beep at all.
nostat can be set to a list of directories and/or
patterns that match directories to prevent the completion mechanism from
stat(2)ing those directories.
listmax and
listmaxrows can be set to limit the number of
items and rows (respectively) that are listed without asking first.
recognize_only_executables can be set to make the
shell list only executables when listing commands, but it is quite slow.
Finally, the
complete builtin command can be used
to tell the shell how to complete words other than filenames, commands and
variables. Completion and listing do not work on glob-patterns (see
Filename
substitution), but the
list-glob and
expand-glob editor commands perform equivalent
functions for glob-patterns.
The shell can sometimes correct the spelling of filenames, commands and variable
names as well as completing and listing them.
Individual words can be spelling-corrected with the
spell-word editor command (usually bound to
M-s and
M-S) and the
entire input buffer with
spell-line (usually
bound to
M-$). The
correct shell variable can be set to
‘
cmd
’ to correct the command name or
‘
all
’ to correct the entire line each
time return is typed, and
autocorrect can be set
to correct the word to be completed before each completion attempt.
When spelling correction is invoked in any of these ways and the shell thinks
that any part of the command line is misspelled, it prompts with the corrected
line:
> set correct = cmd
> lz /usr/bin
CORRECT>ls /usr/bin (y|n|e|a)?
One can answer ‘
y
’ or space to execute the
corrected line, ‘
e
’ to leave the
uncorrected command in the input buffer,
‘
a
’ to abort the command as if
^C had been hit, and anything else to execute the
original line unchanged.
Spelling correction recognizes user-defined completions (see the
complete builtin command). If an input word in a
position for which a completion is defined resembles a word in the completion
list, spelling correction registers a misspelling and suggests the latter word
as a correction. However, if the input word does not match any of the possible
completions for that position, spelling correction does not register a
misspelling.
Like completion, spelling correction works anywhere in the line, pushing the
rest of the line to the right and possibly leaving extra characters to the
right of the cursor.
bindkey lists key bindings and
bindkey -l lists and briefly describes editor
commands. Only new or especially interesting editor commands are described
here. See
emacs(1) and
vi(1) for descriptions of each editor's key
bindings.
The character or characters to which each command is bound by default is given
in parentheses.
^character means
a control character and
M-character a
meta character, typed as
escape-character
(or
^[
character)
on terminals without a meta key. Case counts, but commands that are bound to
letters by default are bound to both lower- and uppercase letters for
convenience.
Supported editor commands are:
-
backward-char
(^B, left)
- Move back a character. Cursor behavior modified by
vimode.
-
backward-delete-word
(M-^H, M-^?)
- Cut from beginning of current word to cursor - saved in cut
buffer. Word boundary behavior modified by
vimode.
-
backward-word
(M-b, M-B)
- Move to beginning of current word. Word boundary and cursor
behavior modified by vimode.
-
beginning-of-line
(^A, home)
- Move to beginning of line. Cursor behavior modified by
vimode.
-
capitalize-word
(M-c, M-C)
- Capitalize the characters from cursor to end of current
word. Word boundary behavior modified by
vimode.
-
complete-word
(tab)
- Completes a word as described under
Completion and
listing (+).
-
complete-word-back
(not bound)
- Like complete-word-fwd, but
steps up from the end of the list.
-
complete-word-fwd
(not bound)
- Replaces the current word with the first word in the list
of possible completions. May be repeated to step down through the list. At
the end of the list, beeps and reverts to the incomplete word.
-
complete-word-raw
(^X-tab)
- Like complete-word, but
ignores user-defined completions.
-
copy-prev-word
(M-^_)
- Copies the previous word in the current line into the input
buffer. See also insert-last-word. Word
boundary behavior modified by vimode.
-
dabbrev-expand
(M-/)
- Expands the current word to the most recent preceding one
for which the current is a leading substring, wrapping around the history
list (once) if necessary. Repeating
dabbrev-expand without any intervening typing
changes to the next previous word etc., skipping identical matches much
like history-search-backward does.
-
delete-char
(not bound)
- Deletes the character under the cursor. See also
delete-char-or-list-or-eof. Cursor behavior
modified by vimode.
-
delete-char-or-eof
(not bound)
- Does delete-char if there is a
character under the cursor or end-of-file on
an empty line. See also
delete-char-or-list-or-eof. Cursor behavior
modified by vimode.
-
delete-char-or-list
(not bound)
- Does delete-char if there is a
character under the cursor or list-choices at
the end of the line. See also
delete-char-or-list-or-eof.
-
delete-char-or-list-or-eof
(^D)
- Does delete-char if there is a
character under the cursor, list-choices at
the end of the line or end-of-file on an
empty line. See also those three commands, each of which does only a
single action, and delete-char-or-eof,
delete-char-or-list, and
list-or-eof, each of which does a different
two out of the three.
-
delete-word
(M-d, M-D)
- Cut from cursor to end of current word - save in cut
buffer. Word boundary behavior modified by
vimode.
-
down-history
(down, ^N)
- Like up-history, but steps
down, stopping at the original input line.
-
downcase-word
(M-l, M-L)
- Lowercase the characters from cursor to end of current
word. Word boundary behavior modified by
vimode.
-
end-of-file
(not bound)
- Signals an end of file, causing the shell to exit unless
the ignoreeof shell variable is set to
prevent this. See also
delete-char-or-list-or-eof.
-
end-of-line
(^E, end)
- Move cursor to end of line. Cursor behavior modified by
vimode.
-
expand-history
(M-space)
- Expands history substitutions in the current word. See
History
substitution. See also magic-space,
toggle-literal-history, and the
autoexpand shell variable.
-
expand-glob
(^X-*)
- Expands the glob-pattern to the left of the cursor. See
Filename
substitution.
-
expand-line
(not bound)
- Like expand-history, but
expands history substitutions in each word in the input buffer.
-
expand-variables
(^X-$)
- Expands the variable to the left of the cursor. See
Variable
substitution.
-
forward-char
(^F, right)
- Move forward one character. Cursor behavior modified by
vimode.
-
forward-word
(M-f, M-F)
- Move forward to end of current word. Word boundary and
cursor behavior modified by vimode.
-
history-search-backward
(M-p, M-P)
- Searches backwards through the history list for a command
beginning with the current contents of the input buffer up to the cursor
and copies it into the input buffer. The search string may be a
glob-pattern (see
Filename
substitution) containing ‘
*
’,
‘?
’,
‘[]
’, or
‘{}
’.
up-history and
down-history will proceed from the
appropriate point in the history list. Emacs mode only. See also
history-search-forward and
i-search-back.
-
history-search-forward
(M-n, M-N)
- Like history-search-backward,
but searches forward.
-
i-search-back
(not bound)
- Searches backward like
history-search-backward, copies the first
match into the input buffer with the cursor positioned at the end of the
pattern, and prompts with
bck:
and the first match. Additional characters may be typed to extend the
search, i-search-back may be typed to
continue searching with the same pattern, wrapping around the history list
if necessary, (i-search-back must be bound to
a single character for this to work) or one of the following special
characters may be typed:
Any other character not bound to
self-insert-command terminates the search,
leaving the current line in the input buffer, and is then interpreted as
normal input. In particular, a carriage return causes the current line to
be executed. See also i-search-fwd and
history-search-backward. Word boundary
behavior modified by vimode.
-
i-search-fwd
(not bound)
- Like i-search-back, but
searches forward. Word boundary behavior modified by
vimode.
-
insert-last-word
(M-_)
- Inserts the last word of the previous input line
(‘
!$
’) into the input buffer. See
also copy-prev-word.
-
list-choices
(M-^D)
- Lists completion possibilities as described under
Completion and
listing (+). See also
delete-char-or-list-or-eof and
list-choices-raw.
-
list-choices-raw
(^X-^D)
- Like list-choices, but ignores
user-defined completions.
-
list-glob
(^X-g, ^X-G)
- Lists (via the ls-F builtin)
matches to the glob-pattern (see
Filename
substitution) to the left of the cursor.
-
list-or-eof
(not bound)
- Does list-choices or
end-of-file on an empty line. See also
delete-char-or-list-or-eof.
-
magic-space
(not bound)
- Expands history substitutions in the current line, like
expand-history, and inserts a space.
magic-space is designed to be bound to the
space bar, but is not bound by default.
-
normalize-command
(^X-?)
- Searches for the current word in
PATH
and, if it is found, replaces it
with the full path to the executable. Special characters are quoted.
Aliases are expanded and quoted but commands within aliases are not. This
command is useful with commands that take commands as arguments, e.g.,
‘dbx
’ and
‘sh -x
’.
-
normalize-path
(^X-n, ^X-N)
- Expands the current word as described under the
‘
expand
’ setting of the
symlinks shell variable.
-
overwrite-mode
(unbound)
- Toggles between input and overwrite modes.
-
run-fg-editor
(M-^Z)
- Saves the current input line and looks for a stopped job
where the file name portion of its first word is found in the
editors shell variable. If
editors is not set, then the file name
portion of the
EDITOR
environment
variable (‘ed
’ if unset) and the
VISUAL
environment variable
(‘vi
’ if unset) will be used. If
such a job is found, it is restarted as if ‘fg
%job
’ had been typed. This
is used to toggle back and forth between an editor and the shell easily.
Some people bind this command to ^Z so they
can do this even more easily.
-
run-help
(M-h, M-H)
- Searches for documentation on the current command, using
the same notion of “current command” as the completion
routines, and prints it. There is no way to use a pager;
run-help is designed for short help files. If
the special alias helpcommand is defined, it
is run with the command name as a sole argument. Else, documentation
should be in a file named command.help,
command.1,
command.6,
command.8, or
command, which should be in one of the
directories listed in the
HPATH
environment variable. If there is more than one help file only the first
is printed.
-
self-insert-command
(text characters)
- In insert mode (the default), inserts the typed character
into the input line after the character under the cursor. In overwrite
mode, replaces the character under the cursor with the typed character.
The input mode is normally preserved between lines, but the
inputmode shell variable can be set to
‘
insert
’ or
‘overwrite
’ to put the editor in
that mode at the beginning of each line. See also
overwrite-mode.
-
sequence-lead-in
(arrow prefix, meta prefix,
^X)
- Indicates that the following characters are part of a
multi-key sequence. Binding a command to a multi-key sequence really
creates two bindings: the first character to
sequence-lead-in and the whole sequence to
the command. All sequences beginning with a character bound to
sequence-lead-in are effectively bound to
undefined-key unless bound to another
command.
-
spell-line
(M-$)
- Attempts to correct the spelling of each word in the input
buffer, like spell-word, but ignores words
whose first character is one of ‘
-
’,
‘!
’,
‘^
’, or
‘%
’, or which contain
‘\
’,
‘*
’, or
‘?
’, to avoid problems with
switches, substitutions and the like. See
Spelling
correction (+).
-
spell-word
(M-s, M-S)
- Attempts to correct the spelling of the current word as
described under
Spelling
correction (+). Checks each component of a word which appears to be a
pathname.
-
toggle-literal-history
(M-r, M-R)
- Expands or unexpands history substitutions in the input
buffer. See also expand-history and the
autoexpand shell variable.
-
undefined-key
(any unbound key)
- Beeps.
-
up-history
(up, ^P)
- Copies the previous entry in the history list into the
input buffer. If histlit is set, uses the
literal form of the entry. May be repeated to step up through the history
list, stopping at the top.
-
upcase-word
(M-u, M-U)
- Uppercase the characters from cursor to end of current
word. Word boundary behavior modified by
vimode.
-
vi-beginning-of-next-word
(not bound)
- Vi goto the beginning of next word. Word boundary and
cursor behavior modified by vimode.
-
vi-eword
(not bound)
- Vi move to the end of the current word. Word boundary
behavior modified by vimode.
-
vi-search-back
(?)
- Prompts with
?
for a search string (which may be a glob-pattern, as with
history-search-backward), searches for it and
copies it into the input buffer. The bell rings if no match is found.
Hitting return ends the search and leaves the last match in the input
buffer. Hitting escape ends the search and executes the match.
vi mode only.
-
vi-search-fwd
(/)
- Like vi-search-back, but
searches forward.
-
which-command
(M-?)
- Does a which (see the
description of the builtin command) on the first word of the input
buffer.
-
yank-pop
(M-y)
- When executed immediately after a
yank or another
yank-pop, replaces the yanked string with the
next previous string from the killring. This also has the effect of
rotating the killring, such that this string will be considered the most
recently killed by a later yank command.
Repeating yank-pop will cycle through the
killring any number of times.
The shell splits input lines into words at blanks and tabs. The special
characters ‘
&
’,
‘
|
’,
‘
;
’,
‘
<
’,
‘
>
’,
‘
(
’, and
‘
)
’, and the doubled characters
‘
&&
’,
‘
||
’,
‘
<<
’, and
‘
>>
’ are always separate words,
whether or not they are surrounded by whitespace.
When the shell's input is not a terminal, the character
‘
#
’ is taken to begin a comment. Each
‘
#
’ and the rest of the input line on
which it appears is discarded before further parsing.
A special character (including a blank or tab) may be prevented from having its
special meaning, and possibly made part of another word, by preceding it with
a backslash (‘
\
’) or enclosing it in
single (‘
'
’), double
(‘
"
’), or backward
(‘
`
’) quotes. When not otherwise quoted
a newline preceded by a ‘
\
’ is
equivalent to a blank, but inside quotes this sequence results in a newline.
Furthermore, all
Substitutions except
History substitution
can be prevented by enclosing the strings (or parts of strings) in which they
appear with single quotes or by quoting the crucial character(s) (e.g.,
‘
$
’ or
‘
`
’ for
Variable
substitution or
Command substitution
respectively) with ‘
\
’.
(
Alias substitution is
no exception: quoting in any way any character of a word for which an
alias has been defined prevents substitution of
the alias. The usual way of quoting an alias is to precede it with a
backslash.)
History
substitution is prevented by backslashes but not by single quotes. Strings
quoted with double or backward quotes undergo
Variable
substitution and
Command
substitution, but other substitutions are prevented.
Text inside single or double quotes becomes a single word (or part of one).
Metacharacters in these strings, including blanks and tabs, do not form
separate words. Only in one special case (see
Command
substitution) can a double-quoted string yield parts of more than one
word; single-quoted strings never do. Backward quotes are special: they signal
Command
substitution, which may result in more than one word.
C-style escape sequences can be used in single quoted strings by preceding the
leading quote with ‘
$
’. (+) See
Escape sequences (+)
for a complete list of recognized escape sequences.
Quoting complex strings, particularly strings which themselves contain quoting
characters, can be confusing. Remember that quotes need not be used as they
are in human writing! It may be easier to quote not an entire string, but only
those parts of the string which need quoting, using different types of quoting
to do so if appropriate.
The
backslash_quote shell variable can be set to
make backslashes always quote ‘
\
’,
‘
'
’, and
‘
"
’ (+). This may make complex
quoting tasks easier, but it can cause syntax errors in
csh(1) scripts.
The following escape sequences are always recognized inside a string constructed
using ‘
$''
’, and optionally by the
echo builtin command as controlled by the
echo_style shell variable.
Supported escape sequences are:
- Escape
- Description
\a
- Bell.
\b
- Backspace.
-
\c
c
- The control character denoted by
‘
^c
’
in stty(1). If
c is a backslash, it must be
doubled.
\e
- Escape.
\f
- Form feed.
\n
- Newline.
\r
- Carriage return.
\t
- Horizontal tab.
\v
- Vertical tab.
\\
- Literal backslash.
\'
- Literal single quote.
\"
- Literal double quote.
-
\
nnn
- The character corresponding to the octal number
nnn.
-
\x
nn
- The character corresponding to the hexadecimal number
nn (1-2 hexadecimal digits).
-
\x{
nnnnnnnn}
- The character corresponding to the hexadecimal number
nnnnnnnn (1-8 hexadecimal digits).
-
\u
nnnn
- The Unicode code point
nnnn (1-4 hexadecimal digits).
-
\U
nnnnnnnn
- The Unicode code point
nnnnnnnn (1-8 hexadecimal digits).
The implementations of ‘
\x
’,
‘
\u
’, and
‘
\U
’ in other shells may take a varying
number of digits. It is often safest to use leading zeros to provide the
maximum expected number of digits.
We now describe the various transformations the shell performs on the input in
the order in which they occur. We note in passing the data structures involved
and the commands and variables which affect them. Remember that substitutions
can be prevented by quoting as described under
Lexical structure.
Each command, or “event”, input from the terminal is saved in the
history list. The previous command is always saved, and the
history shell variable can be set to a number to
save that many commands. The
histdup shell
variable can be set to not save duplicate events or consecutive duplicate
events.
Saved commands are numbered sequentially from 1 and stamped with the time. It is
not usually necessary to use event numbers, but the current event number can
be made part of the prompt by placing an
‘
!
’ in the
prompt shell variable.
By default history entries are displayed by printing each parsed token separated
by space; thus the redirection operator
‘
>&!
’ will be displayed as
‘
> & !
’. The shell
actually saves history in expanded and literal (unexpanded) forms. If the
histlit shell variable is set, commands that
display and store history use the literal form.
The
history builtin command can print, store in a
file, restore and clear the history list at any time, and the
savehist and
histfile shell variables can be set to store the
history list automatically on logout and restore it on login.
History substitutions introduce words from the history list into the input
stream, making it easy to repeat commands, repeat arguments of a previous
command in the current command, or fix spelling mistakes in the previous
command with little typing and a high degree of confidence.
History substitutions begin with the character
‘
!
’. They may begin anywhere in the
input stream, but they do not nest. The
‘
!
’ may be preceded by a
‘
\
’ to prevent its special meaning; for
convenience, a ‘
!
’ is passed unchanged
when it is followed by a blank, tab, newline,
‘
=
’ or
‘
(
’.
History substitutions also occur when an input line begins with
‘
^
’; see
History
substitution abbreviation.
The characters used to signal history substitution
(‘
!
’ and
‘
^
’) can be changed by setting the
histchars shell variable. Any input line which
contains a history substitution is printed before it is executed.
A history substitution may have an “event specification” (see
History event
specification), which indicates the event from which words are to be
taken, a “word designator” (see
History word
designators), which selects particular words from the chosen event, and/or
a “word modifier” (see
History word
modifiers), which manipulates the selected words.
A history event specification may be one of (with the history substitution
character ‘
!
’ shown):
- !Event
- History event
specification
-
!
n
- A number, referring to a particular event.
-
!-
n
- An offset, referring to the event
n before the current event.
!#
- The current event. This should be used carefully in
csh(1), where there is no check for
recursion. tcsh allows 10 levels of
recursion. (+)
!!
- The previous event, equivalent to
‘
!-1
’.
-
!
s
- The most recent event whose first word begins with the
string s.
-
!?
s?
- The most recent event which contains the string
s. The second
‘
?
’ can be omitted if it is
immediately followed by a newline.
For example, consider this bit of someone's history list:
9 8:30 nroff -man wumpus.man
10 8:31 cp wumpus.man wumpus.man.old
11 8:36 vi wumpus.man
12 8:37 diff wumpus.man.old wumpus.man
The commands are shown with their event numbers and time stamps. The current
event, which we haven't typed in yet, is event 13.
Typing
!11
or
!-2
refers to event 11.
Typing
!!
refers to the previous event, 12. ‘
!!
’ can
be abbreviated ‘
!
’ if it is followed by
‘
:
’, which is described in
History word
designators and
History word
modifiers.
Typing
!n
refers to event 9, which begins with ‘
n
’.
Typing
!?old?
refers to event 12, which contains ‘
old
’.
Without word designators or modifiers history references simply expand to the
entire event, so we might type
!cp
to redo the ‘
cp
’ command (event 10) or
!!|more
if the ‘
diff
’ output in the previous
event, 12, scrolled off the top of the screen.
History references may be insulated from the surrounding text with braces if
necessary. For example,
!vdoc
would look for a command beginning with
‘
vdoc
’, and, in this example, not find
one, but
!{v}doc
would expand unambiguously to ‘
vi
wumpus.mandoc
’ by matching event 11. Even in braces, history
substitutions do not nest.
(+) While
csh(1) expands, for example,
!3d
to event 3 with the letter ‘
d
’ appended to
it,
tcsh expands it to the last event beginning
with ‘
3d
’; only completely numeric
arguments are treated as event numbers. This makes it possible to recall
events beginning with numbers. To expand
!3d
as in
csh(1) type
!{3}d
To select words from an event we can follow the event specification by a
‘
:
’ and a designator for the desired
words. The words of an input line are numbered from 0, the first (usually
command) word being 0, the second word (first argument) being 1, etc.
The basic word designators are, with columns for a leading
‘
:
’ and a leading
‘
!
’ (for the abbreviated word
designators - see
History
substitution abbreviation):
:Word |
!Word |
History word designator
|
:0 |
|
The first (command) word.
|
: n
|
|
The nth argument.
|
:^ |
!^ |
The first argument, equivalent to
‘:1 ’.
|
:$ |
!$ |
The last argument.
|
:% |
!% |
The word matched by an
? s?
search.
|
: x- y
|
|
A range of words.
|
:- y
|
!- y
|
Equivalent to
‘:0- y’.
|
:* |
!* |
Equivalent to
‘:^-$ ’, but returns nothing if the
event contains only 1 word.
|
: x*
|
|
Equivalent to
‘: x-$ ’.
|
: x-
|
|
Equivalent to
‘: x* ’,
but omitting the last word (‘$ ’).
|
:- |
|
Equivalent to
‘:0- ’; the command and all arguments
except the last argument. |
Selected words are inserted into the command line separated by single blanks.
For example, the ‘
diff
’ command (event 12)
in the history list example in
History event
specification,
diff wumpus.man.old wumpus.man
might have been typed as
diff !!:1.old !!:1
(using ‘
:1
’ to select the first argument
from the previous event) or
diff !-2:2 !-2:1
to select and swap the arguments from the
‘
cp
’ command (event 10). If we didn't
care about the order of the ‘
diff
’ we
might have typed
diff !-2:1-2
or simply
diff !-2:*
The ‘
cp
’ command (event 10) might have
been typed
cp wumpus.man !#:1.old
using ‘
#
’ to refer to the current event.
Typing
!n:- hurkle.man
would reuse the first two words from the
‘
nroff
’ command (event 9) to expand to
nroff -man hurkle.man
The ‘
:
’ separating the event specification
from the word designator can be omitted if the argument selector begins with a
‘
^
’,
‘
$
’,
‘
%
’,
‘
-
’, or
‘
*
’.
For example, our ‘
diff
’ command (event 12)
might have been typed
diff !!^.old !!^
or, equivalently,
diff !!$.old !!$
However, if ‘
!!
’ is abbreviated
‘
!
’, an argument selector beginning with
‘
-
’ will be interpreted as an event
specification.
A history reference may have a word designator but no event specification. It
then references the previous command.
Continuing our ‘
diff
’ command example
(event 12), we could have typed simply
diff !^.old !^
or, to get the arguments in the opposite order, just
diff !*
The word or words in a history reference can be edited, or
“modified”, by following it with one or more modifiers (with the
leading ‘
:
’ shown), each preceded by a
‘
:
’:
- :Word
- History word modifier
:h
- Remove a trailing pathname component, leaving the
head.
:t
- Remove all leading pathname components, leaving the
tail.
:r
- Remove a filename extension
‘.xxx’, leaving the root
name.
:e
- Remove all but the extension.
:u
- Uppercase the first lowercase letter.
:l
- Lowercase the first uppercase letter.
-
:s/
l/
r/
- Substitute l for
r. l is
simply a string like r, not a regular
expression as in the eponymous ed(1) command.
Any character may be used as the delimiter in place of
‘
/
’; a
‘\
’ can be used to quote the
delimiter inside l and
r. The character
‘&
’ in the
r is replaced by
l;
‘\
’ also quotes
‘&
’. If
l is empty (‘’), the
l from a previous substitution or the
s from a previous search or event number
in event specification is used. The trailing delimiter may be omitted if
it is immediately followed by a newline.
:&
- Repeat the previous substitution.
:g
- Apply the following modifier once to each word.
-
:a
(+)
- Apply the following modifier as many times as possible to a
single word. ‘
:a
’ and
‘:g
’ can be used together to apply a
modifier globally. With the ‘:s
’
modifier, only the patterns contained in the original word are
substituted, not patterns that contain any substitution result.
:p
- Print the new command line but do not execute it.
:q
- Quote the substituted words, preventing further
substitutions.
:Q
- Same as ‘
:q
’ but in
addition preserve empty variables as a string containing a NUL. This is
useful to preserve positional arguments for example:
:x
- Like ‘
:q
’, but break
into words at blanks, tabs and newlines.
Modifiers are applied to only the first modifiable word (unless
‘
:g
’ is used). It is an error for no
word to be modifiable.
For example, the ‘
diff
’ command (event 12)
in the history list example in
History event
specification,
diff wumpus.man.old wumpus.man
might have been typed as
diff wumpus.man.old !#^:r
using ‘
:r
’ to remove
‘
.old
’ from the first argument on the
same line (‘
!#^
’).
We could type
echo hello out there
then
echo !*:u
to capitalize ‘
hello
’,
echo !*:au
to upper case the first word to ‘
HELLO
’,
or
echo !*:agu
to upper case all words.
We might follow
mail -s "I forgot my password"
rot
with
!:s/rot/root
to correct the spelling of ‘
root
’ (see
History word
modifiers and
Spelling correction
(+) for different approaches).
(+) In
csh(1) as such, only one modifier may be
applied to each history or variable expansion. In
tcsh, more than one may be used, for example
% mv wumpus.man /usr/share/man/man1/wumpus.1
% man !$:t:r
man wumpus
In
csh(1), the result would be
wumpus.1:r
A substitution followed by a colon may need to be insulated from it with braces:
> mv a.out /usr/games/wumpus
> setenv PATH !$:h:$PATH
Bad ! modifier: $.
> setenv PATH !{-2$:h}:$PATH
setenv PATH /usr/games:/bin:/usr/bin:.
The first attempt would succeed in
csh(1) but fails
in
tcsh, because
tcsh expects another modifier after the second
colon rather than ‘
$
’.
There is a special abbreviation for substitutions;
‘
^
’, when it is the first character on
an input line, is equivalent to ‘
!:s^
’.
Thus, we might follow the example from
History word
modifiers
mail -s "I forgot my password"
rot
with
^rot^root
to make the spelling correction. This is the only history substitution which
does not explicitly begin with ‘
!
’.
Finally, history can be accessed through the editor as well as through the
substitutions just described. The
up-history and
down-history,
history-search-backward and
history-search-forward,
i-search-back and
i-search-fwd,
vi-search-back and
vi-search-fwd,
copy-prev-word and
insert-last-word editor commands search for
events in the history list and copy them into the input buffer. The
toggle-literal-history editor command switches
between the expanded and literal forms of history lines in the input buffer.
expand-history and
expand-line expand history substitutions in the
current word and in the entire input buffer respectively.
The shell maintains a list of aliases which can be set, unset and printed by the
alias and
unalias
commands. After a command line is parsed into simple commands (see
Commands) the first word of each
command, left-to-right, is checked to see if it has an alias. If so, the first
word is replaced by the alias. If the alias contains a history reference, it
undergoes
History
substitution as though the original command were the previous input line.
If the alias does not contain a history reference, the argument list is left
untouched.
Thus if the alias for ‘
ls
’ were
ls -l
the command
ls /usr
would become
ls -l /usr
the argument list here being undisturbed.
If the alias for ‘
lookup
’ were
grep !^ /etc/passwd
then
lookup bill
would become
grep bill /etc/passwd
Aliases can be used to introduce parser metasyntax. For example,
alias print 'pr \!* | lpr'
defines a “command”
(‘
print
’) which
pr(1)s its arguments to the line printer.
Alias substitution is repeated until the first word of the command has no alias.
If an alias substitution does not change the first word (as in the previous
example) it is flagged to prevent a loop. Other loops are detected and cause
an error.
Some aliases are referred to by the shell; see
Special aliases (+).
The shell maintains a list of variables, each of which has as value a list of
zero or more words. The values of shell variables can be displayed and changed
with the
set and
unset commands. The system maintains its own list
of “environment” variables. These can be displayed and changed
with
printenv,
setenv, and
unsetenv.
(+) Variables may be made read-only with
set -r
Read-only variables may not be modified or unset; attempting to do so will cause
an error. Once made read-only, a variable cannot be made writable, so
set -r
should be used with caution. Environment variables cannot be made read-only.
Some variables are set by the shell or referred to by it. For instance, the
argv variable is an image of the shell's argument
list, and words of this variable's value are referred to in special ways. Some
of the variables referred to by the shell are toggles; the shell does not care
what their value is, only whether they are set or not. For instance, the
verbose variable is a toggle which causes command
input to be echoed. The
-v command line option
sets this variable.
Special shell
variables lists all variables which are referred to by the shell.
Other operations treat variables numerically. The
‘
@’ command permits numeric
calculations to be performed and the result assigned to a variable. Variable
values are, however, always represented as (zero or more) strings. For the
purposes of numeric operations, the null string is considered to be zero, and
the second and subsequent words of multi-word values are ignored.
After the input line is aliased and parsed, and before each command is executed,
variable substitution is performed keyed by
‘
$
’ characters. This expansion can be
prevented by preceding the ‘
$
’ with a
‘
\
’ except within
‘
"
’ pairs where it
always occurs, and within
‘
'
’ pairs where it
never occurs. Strings quoted by
‘
`
’ are interpreted later (see
Command
substitution) so ‘
$
’ substitution
does not occur there until later, if at all. A
‘
$
’ is passed unchanged if followed by a
blank, tab, or end-of-line.
Input/output redirections are recognized before variable expansion, and are
variable expanded separately. Otherwise, the command name and entire argument
list are expanded together. It is thus possible for the first (command) word
(to this point) to generate more than one word, the first of which becomes the
command name, and the rest of which become arguments.
Unless enclosed in ‘
"
’ or given the
‘
:q
’ modifier the results of variable
substitution may eventually be command and filename substituted. Within
‘
"
’, a variable whose value
consists of multiple words expands to a (portion of a) single word, with the
words of the variable's value separated by blanks. When the
‘
:q
’ modifier is applied to a
substitution the variable will expand to multiple words with each word
separated by a blank and quoted to prevent later command or filename
substitution.
The editor command
expand-variables, normally bound
to
^X-$, can be used to interactively expand
individual variables.
The following metasequences are provided for introducing variable values into
the shell input:
-
$
name
-
-
${
name}
- Substitutes the words of the value of variable
name, each separated by a blank. Braces
insulate name from following characters
which would otherwise be part of it. Shell variables have names consisting
of letters and digits starting with a letter. The underscore character is
considered a letter. If name is not a
shell variable, but is set in the environment, then that value is returned
(but some of the other forms given below are not available in this case).
-
$
name[
selector]
-
-
${
name[
selector]}
- Substitutes only the selected words from the value of
name. The
selector is subjected to
‘
$
’ substitution and may consist of
a single number or two numbers separated by a
‘-
’. The first word of a variable's
value is numbered ‘1
’. If the first
number of a range is omitted it defaults to
‘1
’. If the last member of a range
is omitted it defaults to
‘$#name
’.
The selector
‘*
’ selects all words. It is not an
error for a range to be empty if the second argument is omitted or in
range.
$0
- Substitutes the name of the file from which command input
is being read. An error occurs if the name is not known.
-
$
number
-
-
${
number}
- Equivalent to
‘
$argv[number]
’.
$*
- Equivalent to
‘
$argv
’, which is equivalent to
‘$argv[*]
’.
Except as noted, it is an error to reference a variable which is not set.
The ‘
:
’ modifiers described under
History word
modifiers, except for ‘
:p
’, can be
applied to the substitutions above. More than one may be used. (+) Braces may
be needed to insulate a variable substitution from a literal colon just as
with
History word
modifiers; any modifiers must appear within the braces.
The following substitutions cannot be modified with
‘
:
’ modifiers:
-
$?
name
-
-
${?
name}
- Substitutes the string
‘
1
’ if
name is set,
‘0
’ if it is not.
$?0
- Substitutes ‘
1
’ if
the current input filename is known,
‘0
’ if it is not. Always
‘0
’ in interactive shells.
-
$#
name
-
-
${#
name}
- Substitutes the number of words in
name.
$#
- Equivalent to
‘
$#argv
’. (+)
-
$%
name
-
-
${%
name}
- Substitutes the number of characters in
name. (+)
-
$%
number
-
-
${%
number}
- Substitutes the number of characters in
‘
$argv[number]
’.
(+)
$?
- Equivalent to
‘
$status
’. (+)
$$
- Substitutes the (decimal) process number of the (parent)
shell.
$!
- Substitutes the (decimal) process number of the last
background process started by this shell. (+)
$_
- Substitutes the command line of the last command executed.
(+)
$<
- Substitutes a line from the standard input, with no further
interpretation thereafter. It can be used to read from the keyboard in a
shell script. (+) While csh(1) always quotes
‘
$<
’, as if it were equivalent to
‘$<:q
’,
tcsh does not. Furthermore, when
tcsh is waiting for a line to be typed the
user may type an interrupt to interrupt the sequence into which the line
is to be substituted, but csh(1) does not
allow this.
The remaining substitutions are applied selectively to the arguments of builtin
commands. This means that portions of expressions which are not evaluated are
not subjected to these expansions. For commands which are not internal to the
shell, the command name is substituted separately from the argument list. This
occurs very late, after input-output redirection is performed, and in a child
of the main shell.
Command substitution is indicated by a command enclosed in
‘
`
’. The output from such a command is
broken into separate words at blanks, tabs and newlines, and null words are
discarded. The output is variable and command substituted and put in place of
the original string.
Command substitutions inside double quotes
(‘
"
’) retain blanks and tabs; only
newlines force new words. The single final newline does not force a new word
in any case. It is thus possible for a command substitution to yield only part
of a word, even if the command outputs a complete line.
By default, the shell since version 6.12 replaces all newline and carriage
return characters in the command by spaces. If this is switched off by
unsetting
csubstnonl, newlines separate commands
as usual.
If a word contains any of the characters
‘
*
’,
‘
?
’,
‘
[
’, or
‘
{
’ or begins with the character
‘
~
’ it is a candidate for filename
substitution, also known as “globbing”. This word is then
regarded as a pattern (“glob-pattern”), and replaced with an
alphabetically sorted list of file names which match the pattern.
In matching filenames, the character ‘
.
’
at the beginning of a filename or immediately following a
‘
/
’, as well as the character
‘
/
’ must be matched explicitly (unless
either
globdot or
globstar or both are set (+)). The character
‘
*
’ matches any string of characters,
including the null string. The character
‘
?
’ matches any single character. The
sequence ‘
[...]
’ matches any one of the
characters enclosed. Within ‘
[...]
’, a
pair of characters separated by ‘
-
’
matches any character lexically between the two.
(+) Some glob-patterns can be negated: The sequence
‘
[^...]
’ matches any single character
not specified by the characters and/or ranges of
characters in the braces.
An entire glob-pattern can also be negated with
‘
^
’:
> echo *
bang crash crunch ouch
> echo ^cr*
bang ouch
Glob-patterns which do not use ‘
?
’,
‘
*
’, or
‘
[]
’, or which use
‘
{}
’ or
‘
~
’ (below) are not negated correctly.
The metanotation ‘
a{b,c,d}e
’ is a
shorthand for ‘
abe ace ade
’.
Left-to-right order is preserved:
/usr/source/s1/{oldls,ls}.c
expands to
/usr/source/s1/oldls.c
/usr/source/s1/ls.c
The results of matches are sorted separately at a low level to preserve this
order:
../{memo,*box}
might expand to
../memo ../box ../mbox
(Note that ‘
memo
’ was not sorted with the
results of matching ‘
*box
’.) It is not
an error when this construct expands to files which do not exist, but it is
possible to get an error from a command to which the expanded list is passed.
This construct may be nested. As a special case the words
‘
{
’,
‘
}
’, and
‘
{}
’ are passed undisturbed.
The character ‘
~
’ at the beginning of a
filename refers to home directories. Standing alone, i.e.,
‘
~
’, it expands to the invoker's home
directory as reflected in the value of the
home
shell variable. When followed by a name consisting of letters, digits and
‘
-
’ characters the shell searches for a
user with that name and substitutes their home directory; thus
~ken
might expand to
/usr/ken
and
~ken/chmach
might expand to
/usr/ken/chmach
If the character ‘
~
’ is followed by a
character other than a letter or ‘
/
’ or
appears elsewhere than at the beginning of a word, it is left undisturbed. A
command like
setenv MANPATH
/usr/share/man:/usr/local/share/man:~/lib/man
does not, therefore, do home directory substitution as one might hope.
It is an error for a glob-pattern containing
‘
*
’,
‘
?
’,
‘
[
’, or
‘
~
’, with or without
‘
^
’, not to match any files. However,
only one pattern in a list of glob-patterns must match a file (so that, e.g.,
rm *.a *.c *.o
would fail only if there were no files in the current directory ending in
‘
.a
’,
‘
.c
’, or
‘
.o
’), and if the
nonomatch shell variable is set a pattern (or
list of patterns) which matches nothing is left unchanged rather than causing
an error.
The
globstar shell variable can be set to allow
‘
**
’ or
‘
***
’ as a file glob pattern that
matches any string of characters including
‘
/
’, recursively traversing any existing
sub-directories. For example,
ls **.c
will list all the .c files in the current directory tree. If used by itself, it
will match zero or more sub-directories. For example
ls /usr/include/**/time.h
will list any file named ‘
time.h
’ in the
/usr/include directory tree;
ls /usr/include/**time.h
will match any file in the
/usr/include directory
tree ending in ‘
time.h
’; and
ls /usr/include/**time**.h
will match any .h file with ‘
time
’ either
in a subdirectory name or in the filename itself. To prevent problems with
recursion, the ‘
**
’ glob-pattern will
not descend into a symbolic link containing a directory. To override this, use
‘
***
’ (+)
The
noglob shell variable can be set to prevent
filename substitution, and the
expand-glob editor
command, normally bound to
^X-*, can be used to
interactively expand individual filename substitutions.
The directory stack is a list of directories, numbered from zero, used by the
pushd,
popd, and
dirs builtin commands.
dirs can print, store in a file, restore and
clear the directory stack at any time, and the
savedirs and
dirsfile shell variables can be set to store the
directory stack automatically on logout and restore it on login. The
dirstack shell variable can be examined to see
the directory stack and set to put arbitrary directories into the directory
stack.
The character ‘
=
’ followed by one or more
digits expands to an entry in the directory stack. The special case
‘
=-
’ expands to the last directory in
the stack. For example,
> dirs -v
0 /usr/bin
1 /usr/spool/uucp
2 /usr/accts/sys
> echo =1
/usr/spool/uucp
> echo =0/calendar
/usr/bin/calendar
> echo =-
/usr/accts/sys
The
noglob and
nonomatch shell variables and the
expand-glob editor command apply to directory
stack as well as filename substitutions.
There are several more transformations involving filenames, not strictly related
to the above but mentioned here for completeness.
Any filename may be expanded to a full path when
the
symlinks variable is set to
‘
expand
’. Quoting prevents this
expansion, and the
normalize-path editor command
does it on demand. The
normalize-command editor
command expands commands in
PATH
into full
paths on demand. Finally,
cd and
pushd interpret
‘
-
’ as the old working directory
(equivalent to the shell variable
owd). This is
not a substitution at all, but an abbreviation recognized by only those
commands. Nonetheless, it too can be prevented by quoting.
The next three sections describe how the shell executes commands and deals with
their input and output.
A simple command is a sequence of words, the first of which specifies the
command to be executed. A series of simple commands joined by
‘
|
’ characters forms a pipeline. The
output of each command in a pipeline is connected to the input of the next.
Simple commands and pipelines may be joined into sequences with
‘
;
’, and will be executed sequentially.
Commands and pipelines can also be joined into sequences with
‘
||
’ or
‘
&&
’, indicating, as in the C
language, that the second is to be executed only if the first fails or
succeeds respectively.
A simple command, pipeline or sequence may be placed in parentheses,
‘
()
’, to form a simple command, which
may in turn be a component of a pipeline or sequence. A command, pipeline or
sequence can be executed without waiting for it to terminate by following it
with an ‘
&
’.
Builtin commands are executed within the shell. If any component of a pipeline
except the last is a builtin command, the pipeline is executed in a subshell.
Parenthesized commands are always executed in a subshell.
thus prints the
home directory, leaving you where
you were (printing this after the home directory), while
leaves you in the
home directory. Parenthesized
commands are most often used to prevent
cd from
affecting the current shell.
When a command to be executed is found not to be a builtin command the shell
attempts to execute the command via
execve(2).
Each word in the variable
path names a directory
in which the shell will look for the command. If the shell is not given a
-f option, the shell hashes the names in these
directories into an internal table so that it will try an
execve(2) in only a directory where there is a
possibility that the command resides there. This greatly speeds command
location when a large number of directories are present in the search path.
This hashing mechanism is not used:
- If hashing is turned explicitly off via
unhash.
- If the shell was given a -f
argument.
- For each directory component of
path which does not begin with a
‘
/
’.
- If the command contains a
‘
/
’.
In the above four cases the shell concatenates each component of the path vector
with the given command name to form a path name of a file which it then
attempts to execute it. If execution is successful, the search stops.
If the file has execute permissions but is not an executable to the system
(i.e., it is neither an executable binary nor a script that specifies its
interpreter), then it is assumed to be a file containing shell commands and a
new shell is spawned to read it. The
shell
special alias may be set to specify an interpreter other than the shell
itself.
On systems which do not understand the
‘
#!
’ script interpreter convention the
shell may be compiled to emulate it; see the
version shell variable. If so, the shell checks
the first line of the file to see if it is of the form
#!interpreter
arg ...
If it is, the shell starts
interpreter with the
given
args and feeds the file to it on
standard input.
The standard input and standard output of a command may be redirected with the
following syntax:
-
<
name
- Open file name (which is
first variable, command and filename expanded) as the standard input.
-
<<
word
- Read the shell input up to a line which is identical to
word.
word is not subjected to variable,
filename or command substitution, and each input line is compared to
word before any substitutions are done on
this input line. Unless a quoting
‘
\
’,
‘"
’,
‘'
’, or
‘`
’ appears in
word variable and command substitution is
performed on the intervening lines, allowing
‘\
’ to quote
‘$
’,
‘\
’, and
‘`
’. Commands which are substituted
have all blanks, tabs, and newlines preserved, except for the final
newline which is dropped. The resultant text is placed in an anonymous
temporary file which is given to the command as standard input.
-
>
name
-
-
>!
name
-
-
>&
name
-
-
>&!
name
- The file name is used as
standard output. If the file does not exist then it is created; if the
file exists, it is truncated, its previous contents being lost.
If the shell variable noclobber is set, then
the file must not exist or be a character special file (e.g., a terminal
or /dev/null) or an error results. This helps
prevent accidental destruction of files. In this case the
‘
!
’ forms can be used to suppress
this check. If ‘notempty
’ is given
in noclobber,
‘>
’ is allowed on empty files; if
‘ask
’ is given in
noclobber, an interacive confirmation is
presented, rather than an error.
The forms involving ‘&
’ route the
diagnostic output into the specified file as well as the standard output.
name is expanded in the same way as
‘<
’ input filenames are.
-
>>
name
-
-
>>&
name
-
-
>>!
name
-
-
>>&!
name
- Like ‘
>
’, but
appends output to the end of name. If the
shell variable noclobber is set, then it is
an error for the file not to exist, unless
one of the ‘!
’ forms is given.
A command receives the environment in which the shell was invoked as modified by
the input-output parameters and the presence of the command in a pipeline.
Thus, unlike some previous shells, commands run from a file of shell commands
have no access to the text of the commands by default; rather they receive the
original standard input of the shell. The
‘
<<
’ mechanism should be used to
present inline data. This permits shell command scripts to function as
components of pipelines and allows the shell to block read its input. Note
that the default standard input for a command run detached is
not the empty file
/dev/null, but the original standard input of the
shell. If this is a terminal and if the process attempts to read from the
terminal, then the process will block and the user will be notified (see
Jobs).
Diagnostic output may be directed through a pipe with the standard output.
Simply use the form ‘
|&
’ rather than
just ‘
|
’.
The shell cannot presently redirect diagnostic output without also redirecting
standard output, but
( command
>
output-file )
>&
error-file
is often an acceptable workaround. Either
output-file or
error-file may be
/dev/tty to send output to the terminal.
Having described how the shell accepts, parses and executes command lines, we
now turn to a variety of its useful features.
The shell contains a number of commands which can be used to regulate the flow
of control in command files (shell scripts) and (in limited but useful ways)
from terminal input. These commands all operate by forcing the shell to reread
or skip in its input and, due to the implementation, restrict the placement of
some of the commands.
The
foreach,
switch,
and
while statements, as well as the
if ... then ... else form of the
if statement, require that the major keywords
appear in a single simple command on an input line as shown below.
If the shell's input is not seekable, the shell buffers up input whenever a loop
is being read and performs seeks in this internal buffer to accomplish the
rereading implied by the loop. (To the extent that this allows, backward
gotos will succeed on non-seekable inputs.)
The
if,
while, and
exit builtin commands use expressions with a
common syntax. The expressions can include any of the operators described in
the next three sections. Note that the
@ builtin
command has its own separate syntax.
These operators are similar to those of C and have the same precedence.
The operators, in descending precedence, with equivalent precedence per line,
are:
The ‘
==
’
‘
!=
’
‘
=~
’ and
‘
!~
’ operators compare their arguments
as strings; all others operate on numbers. The operators
‘
=~
’ and
‘
!~
’ are like
‘
==
’ and
‘
!=
’ except that the right hand side is
a glob-pattern (see
Filename
substitution) against which the left hand operand is matched. This reduces
the need for use of the
switch builtin command in
shell scripts when all that is really needed is pattern matching.
Null or missing arguments are considered
‘
0
’. The results of all expressions are
strings, which represent decimal numbers. It is important to note that no two
components of an expression can appear in the same word; except when adjacent
to components of expressions which are syntactically significant to the parser
(‘
&
’,
‘
|
’,
‘
<
’,
‘
>
’,
‘
(
’,
‘
)
’) they should be surrounded by
spaces.
Commands can be executed in expressions and their exit status returned by
enclosing them in braces (‘
{}
’).
Remember that the braces should be separated from the words of the command by
spaces. Command executions succeed, returning true, i.e.,
‘
1
’, if the command exits with status 0,
otherwise they fail, returning false, i.e.,
‘
0
’. If more detailed status information
is required then the command should be executed outside of an expression and
the
status shell variable examined.
Some of these operators perform true/false tests on files and related objects.
They are of the form
-op file, where
-op is one of:
- -op
-
True/false file inquiry
operator
- -r
- Read access.
- -w
- Write access.
- -x
- Execute access.
- -X
- Executable in the path or shell builtin, e.g.,
‘
-X ls
’ and
‘-X ls-F
’ are generally true, but
‘-X /bin/ls
’ is not. (+)
- -e
- Existence.
- -o
- Ownership.
- -z
- Zero size.
- -s
- Non-zero size. (+)
- -f
- Plain file.
- -d
- Directory.
- -l
- Symbolic link. (+) *
- -b
- Block special file. (+)
- -c
- Character special file. (+)
- -p
- Named pipe (fifo). (+) *
- -S
- Socket special file. (+) *
- -u
- Set-user-ID bit is set. (+)
- -g
- Set-group-ID bit is set. (+)
- -k
- Sticky bit is set. (+)
- -t
-
file (which must be a
digit) is an open file descriptor for a terminal device. (+)
- -R
- Has been migrated (Convex only). (+)
- -L
- Applies subsequent operators in a multiple-operator test to
a symbolic link rather than to the file to which the link points. (+)
*
file is command and filename expanded and then
tested to see if it has the specified relationship to the real user. If
file does not exist or is inaccessible or,
for the operators indicated by ‘*’, if the specified file type
does not exist on the current system, then all inquiries return false, i.e.,
‘
0
’.
These operators may be combined for conciseness:
-xy
file
is equivalent to
-x
file &&
-y
file
(+) For example, ‘
-fx
’ is true (returns
‘
1
’) for plain executable files, but not
for directories.
-L may be used in a multiple-operator test to apply
subsequent operators to a symbolic link rather than to the file to which the
link points. For example,
-lLo is true for links
owned by the invoking user.
-Lr,
-Lw, and
-Lx are
always true for links and false for non-links.
-L
has a different meaning when it is the last operator in a multiple-operator
test; see below.
It is possible but not useful, and sometimes misleading, to combine operators
which expect
file to be a file with operators
which do not (e.g.,
-X and
-t). Following
-L
with a non-file operator can lead to particularly strange results.
Other operators return other information, i.e., not just
‘
0
’ or
‘
1
’. (+) They have the same format as
before;
-op may
be one of:
- -op
-
Extended file inquiry operator
- -A
- Last file access time, as the number of seconds since the
epoch.
- -A:
- Like ‘
A
’, but in
timestamp format, e.g., ‘Fri May 14 16:36:10 1993’.
- -M
- Last file modification time.
- -M:
- Like -M, but in timestamp
format.
- -C
- Last inode modification time.
- -C:
- Like -C, but in timestamp
format.
- -D
- Device number.
- -I
- Inode number.
- -F
- Composite -file identifier, in
the form
device:inode.
- -L
- The name of the file pointed to by a symbolic link.
- -N
- Number of (hard) links.
- -P
- Permissions, in octal, without leading zero.
- -P:
- Like -P, with leading
zero.
-
-Pmode
- Equivalent to
-P
file &
mode
For example, ‘-P22
file
’ returns
‘22’ if file is writable by
group and other, ‘20’ if by group only, and
‘0’ if by neither.
-
-Pmode
:
- Like
-Pmode, with
leading zero.
- -U
- Numeric userid.
- -U:
- Username, or the numeric userid if the username is
unknown.
- -G
- Numeric groupid.
- -G:
- Groupname, or the numeric groupid if the groupname is
unknown.
- -Z
- Size, in bytes.
Only one of these operators may appear in a multiple-operator test, and it must
be the last. Note that ‘
L
’ has a
different meaning at the end of and elsewhere in a multiple-operator test.
Because ‘0’ is a valid return value for many of these operators,
they do not return ‘0’ when they fail: most return
‘-1’, and ‘
F
’ returns
‘
:
’.
If the shell is compiled with POSIX defined (see the
version shell variable), the result of a file
inquiry is based on the permission bits of the file and not on the result of
the
access(2) system call. For example, if one
tests a file with
-w whose permissions would
ordinarily allow writing but which is on a file system mounted read-only, the
test will succeed in a POSIX shell but fail in a non-POSIX shell.
File inquiry operators can also be evaluated with the
filetest builtin command (+).
The shell associates a
job with each pipeline.
It keeps a table of current jobs, printed by the
jobs command, and assigns them small integer
numbers. When a job is started asynchronously with
‘
&
’, the shell prints a line which
looks like
indicating that the job which was started asynchronously was job number 1 and
had one (top-level) process, whose process id was 1234.
If you are running a job and wish to do something else you may hit the suspend
key (usually
^Z), which sends a STOP signal to
the current job. The shell will then normally indicate that the job has been
Suspended
and print another prompt. If the
listjobs shell
variable is set, all jobs will be listed like the
jobs builtin command; if it is set to
‘
long
’ the listing will be in long
format, like ‘
jobs -l
’. You can then
manipulate the state of the suspended job. You can put it in the
“background” with the
bg command or
run some other commands and eventually bring the job back into the
“foreground” with
fg. (See also the
run-fg-editor editor command.) A
^Z takes effect immediately and is like an
interrupt in that pending output and unread input are discarded when it is
typed. The
wait builtin command causes the shell
to wait for all background jobs to complete.
The
^] key sends a delayed suspend signal, which
does not generate a STOP signal until a program attempts to
read(2) it, to the current job. This can usefully
be typed ahead when you have prepared some commands for a job which you wish
to stop after it has read them. The
^Y key
performs this function in
csh(1); in
tcsh,
^Y is an
editing command. (+)
A job being run in the background stops if it tries to read from the terminal.
Background jobs are normally allowed to produce output, but this can be
disabled by giving the command
stty tostop
If you set this tty option, then background jobs will stop when they try to
produce output like they do when they try to read input.
There are several ways to refer to jobs in the shell. The character
‘
%
’ introduces a job name. If you wish
to refer to job number 1, you can name it as
%1
Just naming a job brings it to the foreground; thus
%1
is a synonym for
fg %1
bringing job 1 back into the foreground. Similarly, typing
%1 &
resumes job 1 in the background, just like
bg %1
A job can also be named by an unambiguous prefix of the string typed in to start
it:
%ex
would normally restart a suspended
ex(1) job, if
there were only one suspended job whose name began with the string
‘
ex
’. It is also possible to type
%?string
to specify a job whose text contains
string, if
there is only one such job.
The shell maintains a notion of the current and previous jobs. In output
pertaining to jobs, the current job is marked with a
‘
+
’ and the previous job with a
‘
-
’. The abbreviations
‘
%+
’,
‘
%
’, and (by analogy with the syntax of
the
history mechanism)
‘
%%
’ all refer to the current job, and
‘
%-
’ refers to the previous job.
The job control mechanism requires that the
stty(1)
option ‘
new
’ be set on some systems. It
is an artifact from a “new” implementation of the tty driver
which allows generation of interrupt characters from the keyboard to tell jobs
to stop. See
stty(1) and the
setty builtin command for details on setting
options in the new tty driver.
The shell learns immediately whenever a process changes state. It normally
informs you whenever a job becomes blocked so that no further progress is
possible, but only right before it prints a prompt. This is done so that it
does not otherwise disturb your work. If, however, you set the shell variable
notify, the shell will notify you immediately of
changes of status in background jobs. There is also a builtin command
notify which marks a single process so that its
status changes will be immediately reported. By default
notify marks the current process; simply enter
notify
after starting a background job to mark it for immediate status reporting.
When you try to leave the shell while jobs are stopped, you will be warned that
There are suspended jobs.
You may use the
jobs command to see what they are.
If you do this or immediately try to exit again, the shell will not warn you a
second time, and the suspended jobs will be terminated.
There are various ways to run commands and take other actions automatically at
various times in the “life cycle” of the shell. They are
summarized here, and described in detail under the appropriate
Builtin commands,
Special shell
variables, and
Special aliases (+).
The
sched builtin command puts commands in a
scheduled-event list, to be executed by the shell at a given time.
The
beepcmd,
cwdcmd,
jobcmd,
periodic,
precmd, and
postcmd
Special aliases (+)
can be set, respectively, to execute commands: when the shell wants to ring
the bell, when the working directory changes, when a job is started or is
brought into the foreground, every
tperiod
minutes, before each prompt, and before each command gets executed.
The
autologout shell variable can be set to log out
or lock the shell after a given number of minutes of inactivity.
The
mail shell variable can be set to check for new
mail periodically.
The
printexitvalue shell variable can be set to
print the exit status of commands which exit with a status other than zero.
The
rmstar shell variable can be set to ask the
user, when
rm *
is typed, if that is really what was meant.
The
time shell variable can be set to execute the
time builtin command after the completion of any
process that takes more than a given number of CPU seconds.
The
watch and
who
shell variables can be set to report when selected users log in or out, and
the
log builtin command reports on those users at
any time.
The shell is eight bit clean (if so compiled; see the
version shell variable) and thus supports
character sets needing this capability. NLS support differs depending on
whether or not the shell was compiled to use the system's NLS (again, see
version). In either case, 7-bit ASCII is the
default character code (e.g., the classification of which characters are
printable) and sorting, and changing the
LANG
or
LC_CTYPE
environment variables causes a
check for possible changes in these respects.
When using the system's NLS, the
setlocale(3)
function is called to determine appropriate character code/classification and
sorting (e.g., ‘en_CA.UTF-8’ would yield ‘UTF-8’
as the character code). This function typically examines the
LANG
and
LC_CTYPE
environment variables; refer to
the system documentation for further details. When not using the system's NLS,
the shell simulates it by assuming that the ISO 8859-1 character set is used
whenever either of the
LANG
and
LC_CTYPE
variables are set, regardless of
their values. Sorting is not affected for the simulated NLS.
In addition, with both real and simulated NLS, all printable characters in the
range \200-\377, i.e., those that have
M-char bindings,
are automatically rebound to
self-insert-command.
The corresponding binding for the
escape-char sequence,
if any, is left alone. These characters are not rebound if the
NOREBIND
environment variable is set. This
may be useful for the simulated NLS or a primitive real NLS which assumes full
ISO 8859-1. Otherwise, all
M-char bindings
in the range \240-\377 are effectively undone. Explicitly rebinding the
relevant keys with
bindkey is of course still
possible.
Unknown characters (i.e., those that are neither printable nor control
characters) are printed in the format \nnn. If the tty is not in 8 bit mode,
other 8 bit characters are printed by converting them to ASCII and using
standout mode. The shell never changes the 7/8 bit mode of the tty and tracks
user-initiated changes of 7/8 bit mode. NLS users (or, for that matter, those
who want to use a meta key) may need to explicitly set the tty in 8 bit mode
through the appropriate
stty(1) command in, e.g.,
the
~/.login file.
A number of new builtin commands are provided to support features in particular
operating systems. All are described in detail in the
Builtin commands
section.
On systems that support TCF (aix-ibm370, aix-ps2),
getspath and
setspath get and set the system execution path,
getxvers and
setxvers get and set the experimental version
prefix and
migrate migrates processes between
sites. The
jobs builtin prints the site on which
each job is executing.
Under BS2000,
bs2cmd executes commands of the
underlying BS2000/OSD operating system.
Under Domain/OS,
inlib adds shared libraries to the
current environment,
rootnode changes the
rootnode and
ver changes the systype.
Under Mach,
setpath is equivalent to Mach's
setpath(1).
Under Masscomp/RTU and Harris CX/UX,
universe sets
the universe.
Under Harris CX/UX,
ucb or
att runs a command under the specified universe.
Under Convex/OS,
warp prints or sets the universe.
The
VENDOR
,
OSTYPE
, and
MACHTYPE
environment variables indicate
respectively the vendor, operating system and machine type (microprocessor
class or machine model) of the system on which the shell thinks it is running.
These are particularly useful when sharing one's home directory between
several types of machines; one can, for example,
set path = (~/bin.$MACHTYPE /usr/ucb /bin /usr/bin .)
in one's
~/.login and put executables compiled for
each machine in the appropriate directory.
The
version shell variable indicates what options
were chosen when the shell was compiled.
Note also the
newgrp builtin, the
afsuser and
echo_style shell variables and the
system-dependent locations of the shell's input files (see
FILES).
Login shells ignore interrupts when reading the file
~/.logout. The shell ignores quit signals unless
started with
-q. Login shells catch the terminate
signal, but non-login shells inherit the terminate behavior from their
parents. Other signals have the values which the shell inherited from its
parent.
In shell scripts, the shell's handling of interrupt and terminate signals can be
controlled with
onintr, and its handling of
hangups can be controlled with
hup and
nohup.
The shell exits on a hangup (see also the
logout
shell variable). By default, the shell's children do too, but the shell does
not send them a hangup when it exits.
hup
arranges for the shell to send a hangup to a child when it exits, and
nohup sets a child to ignore hangups.
The shell uses three different sets of terminal (“tty”) modes:
‘edit’, used when editing; ‘quote’, used when
quoting literal characters; and ‘execute’, used when executing
commands. The shell holds some settings in each mode constant, so commands
which leave the tty in a confused state do not interfere with the shell. The
shell also matches changes in the speed and padding of the tty. The list of
tty modes that are kept constant can be examined and modified with the
setty builtin. Note that although the editor uses
CBREAK mode (or its equivalent), it takes typed-ahead characters anyway.
The
echotc,
settc, and
telltc commands can be used to manipulate and
debug terminal capabilities from the command line.
On systems that support SIGWINCH or SIGWINDOW, the shell adapts to window
resizing automatically and adjusts the environment variables
LINES
and
COLUMNS
if set. If the environment variable
TERMCAP
contains
‘
li#
’ and
‘
co#
’ fields, the shell adjusts them to
reflect the new window size.
The next sections of this manual describe all of the available
Builtin commands,
Special aliases (+),
and
Special shell
variables.
-
%job
- A synonym for the fg builtin
command.
-
%job
&
- A synonym for the bg builtin
command.
- :
- Does nothing, successfully.
- @
-
-
@
name =
expr
-
-
@
name[index]
= expr
-
-
@
name++|--
-
-
@
name[index]++|--
- The first form prints the values of all shell variables.
The second form assigns the value of expr
to name.
The third form assigns the value of expr to
the index'th component of
name; both
name and its
index'th component must already exist.
expr may contain the operators
‘
*
’,
‘+
’, etc., as in C. If
expr contains
‘<
’,
‘>
’,
‘&
’, or
‘|
’ then at least that part of
expr must be placed within
(‘
’ and
‘
’). Note that the syntax of
expr has nothing to do with that
described under
Expressions.
The fourth and fifth forms increment
(‘++’) or decrement
(‘--’)
name or its
index'th component.
The space between ‘@’ and
name is required. The spaces between
name and
‘=’ and between
‘=’ and
expr are optional. Components of
expr must be separated by spaces.
-
alias
[name
[wordlist]]
- Without arguments, prints all aliases.
With name, prints the alias for name.
With name and
wordlist, assigns
wordlist as the alias of
name.
wordlist is command and filename
substituted.
name may not be
‘alias’ or
‘unalias’. See also the
unalias builtin command.
- alloc
- Shows the amount of dynamic memory acquired, broken down
into used and free memory. With an argument shows the number of free and
used blocks in each size category. The categories start at size 8 and
double at each step. This command's output may vary across system types,
because systems other than the VAX may use a different memory
allocator.
-
bg
[%job
...]
- Puts the specified jobs (or, without arguments, the current
job) into the background, continuing each if it is stopped.
job may be a number, a string,
‘
’,
‘%
’,
‘+
’, or
‘-
’ as described under
Jobs.
-
bindkey
[-l|-d|-e|-v|-u]
(+)
-
-
bindkey
[-a]
[-b]
[-k]
[-r]
[--]
key (+)
-
-
bindkey
[-a]
[-b]
[-k]
[-c|-s]
[--]
key command
(+)
- The first form either lists all bound keys and the editor
command to which each is bound, lists a description of the commands, or
binds all keys to a specific mode.
The second form lists the editor command to which
key is bound.
The third form binds the editor command
command to
key.
Supported bindkey options:
- Option
-
bindkey
description
- -a
- Lists or changes key-bindings in the alternative key
map. This is the key map used in vimode
command mode.
- -b
-
key is interpreted as
a control character written
^character
(e.g., ^A) or
C-character
(e.g., C-A), a meta character written
M-character
(e.g., M-A), a function key written
F-string
(e.g., F-string), or an extended prefix
key written
X-character
(e.g., X-A).
- -c
-
command is interpreted
as a builtin or external command instead of an editor command.
- -d
- Binds all keys to the standard bindings for the default
editor, as per -e and
-v.
- -e
- Binds all keys to
emacs(1)-style bindings. Unsets
vimode.
- -k
-
key is interpreted as
a symbolic arrow key name, which may be one of ‘down’,
‘up’, ‘left’, or
‘right’.
- -l
- Lists all editor commands and a short description of
each.
- -r
- Removes key's binding.
Be careful: ‘
bindkey -r
’ does
not bind
key to
self-insert-command, it unbinds
key completely.
- -s
-
command is taken as a
literal string and treated as terminal input when
key is typed. Bound keys in
command are themselves reinterpreted,
and this continues for ten levels of interpretation.
-
-u
(or any invalid option)
- Prints a usage message.
- -v
- Binds all keys to
vi(1)-style bindings. Sets
vimode.
- --
- Forces a break from option processing, so the next word
is taken as key even if it begins
with ‘
-
’.
key may be a single character or a string.
If a command is bound to a string, the first character of the string is
bound to sequence-lead-in and the entire
string is bound to the command.
Control characters in key can be literal
(they can be typed by preceding them with the editor command
quoted-insert, normally bound to
^V) or written caret-character style, e.g.,
^A. Delete is written
^? (caret-question mark).
key and
command can contain backslashed escape
sequences (in the style of System V echo(1))
as follows:
- Escape
- Description
\a
- Bell.
\b
- Backspace.
\e
- Escape.
\f
- Form feed.
\n
- Newline.
\r
- Carriage return.
\t
- Horizontal tab.
\v
- Vertical tab.
-
\
nnn
- The ASCII character corresponding to the octal number
nnn.
‘\
’ nullifies the special meaning of
the following character, if it has any, notably
‘\
’ and
‘^
’.
-
bs2cmd
bs2000-command
(+)
- Passes bs2000-command to
the BS2000 command interpreter for execution. Only non-interactive
commands can be executed, and it is not possible to execute any command
that would overlay the image of the current process, like /EXECUTE or
/CALL-PROCEDURE. (BS2000 only)
- break
- Causes execution to resume after the
end of the nearest enclosing
foreach or
while. The remaining commands on the current
line are executed. Multi-level breaks are thus possible by writing them
all on one line.
- breaksw
- Causes a break from a switch,
resuming after the endsw.
-
builtins
(+)
- Prints the names of all builtin commands.
-
bye
(+)
- A synonym for the logout
builtin command. Available only if the shell was so compiled; see the
version shell variable.
-
case
label:
- A label in a switch statement
as discussed below.
-
cd
[-p]
[-l]
[-n|-v]
[--]
[name]
- If a directory name is
given, changes the shell's working directory to
name. If not, changes to
home, unless the
cdtohome variable is not set, in which case a
name is required. If
name is
‘
-
’ it is interpreted as the
previous working directory (see
Other
substitutions (+)). (+) If name is
not a subdirectory of the current directory (and does not begin with
‘/
’,
‘./
’ or
‘../
’), each component of the
variable cdpath is checked to see if it has a
subdirectory name. Finally, if all else
fails but name is a shell variable whose
value begins with ‘/
’ or
‘.
’, then this is tried to see if it
is a directory, and the -p option is implied.
With -p, prints the final directory stack, just
like dirs. The
-l, -n, and
-v flags have the same effect on
cd as on dirs,
and they imply -p (+). Using
-- forces a break from option processing so
the next word is taken as the directory
name even if it begins with
‘-
’ (+).
See also the implicitcd and
cdtohome shell variables.
- chdir
- A synonym for the cd builtin
command.
-
complete
[command
[word/pattern/list[:select]/[[suffix]/]
...]] (+)
- Without arguments, lists all completions.
With command, lists completions for
command.
With command and
word ..., defines completions.
command may be a full command name or a
glob-pattern (see
Filename
substitution). It can begin with
‘
-
’ to indicate that completion
should be used only when command is
ambiguous.
word specifies which word relative to the
current word is to be completed, and may be one of the following:
list, the list of possible completions, may
be one of the following:
select is an optional glob-pattern. If
given, words from only list that match
select are considered and the
fignore shell variable is ignored. The
list types
‘$var
’,
‘(...)
’, and
‘`...`
’ may not have a
select pattern, and
‘x
’ uses
select as an explanatory message when the
list-choices editor command is used.
suffix is a single character to be appended
to a successful completion. If null, no character is appended. If omitted
(in which case the fourth delimiter can also be omitted), a slash is
appended to directories and a space to other words.
command invoked from
list
‘`...`
’ has the additional
environment variable COMMAND_LINE
set,
which contains (as its name indicates) contents of the current (already
typed in) command line. One can examine and use contents of the
COMMAND_LINE
environment variable in a
custom script to build more sophisticated completions (see completion for
svn(1) included in this package).
Now for some examples. Some commands take only directories as arguments, so
there's no point completing plain files.
completes only the first word following
‘cd
’
(‘p/1
’) with a directory.
‘p
’-type completion can also be used
to narrow down command completion:
This completion completes commands (words in position 0,
‘p/0
’) which begin with
‘co
’ (thus matching
‘co*
’) to
‘compress
’ (the only word in the
list). The leading ‘-
’ indicates
that this completion is to be used with only ambiguous commands.
is an example of ‘n
’-type completion.
Any word following ‘find
’ and
immediately following ‘-user
’ is
completed from the list of users.
demonstrates ‘c
’-type completion. Any
word following ‘cc
’ and beginning
with ‘-I
’ is completed as a
directory. ‘-I
’ is not taken as part
of the directory because we used lowercase
‘c
’.
Different lists are
useful with different commands.
These complete words following ‘alias
’
with aliases, ‘man
’ with commands,
and ‘set
’ with shell variables.
true doesn't have any options, so
‘x
’ does nothing when completion is
attempted and prints
Truth has no options.
when completion choices are listed.
Note that the ‘man
’ example, and
several other examples below, could just as well have used
‘'c/*'
’ or
‘'n/*'
’ as
‘'p/*'
’.
Words can be completed from a variable evaluated at completion time,
or from a command run at completion time:
Note that the complete command does not itself
quote its arguments, so the braces, space and
‘$
’ in
‘{print $1}
’ must be quoted
explicitly.
One command can have multiple completions:
completes the second argument to ‘dbx
’
with the word ‘core
’ and all other
arguments with commands. Note that the positional completion is specified
before the next-word completion. Because completions are evaluated from
left to right, if the next-word completion were specified first it would
always match and the positional completion would never be executed. This
is a common mistake when defining a completion.
The select pattern is useful when a command
takes files with only particular forms as arguments. For example,
completes ‘cc
’ arguments to files
ending in only ‘.c
’,
‘.a
’, or
‘.o
’.
select can also exclude files, using
negation of a glob-pattern as described under
Filename
substitution. One might use
to exclude precious source code from
‘rm
’ completion. Of course, one
could still type excluded names manually or override the completion
mechanism using the complete-word-raw or
list-choices-raw editor commands.
The ‘C
’,
‘D
’,
‘F
’, and
‘T
’
lists are like
‘c
’,
‘d
’,
‘f
’, and
‘t
’ respectively, but they use the
select argument in a different way: to
restrict completion to files beginning with a particular path prefix. For
example, the Elm mail program uses
‘=
’ as an abbreviation for one's
mail directory. One might use
to complete
elm -f =
as if it were
elm -f ~/Mail/
Note that we used the separator ‘@
’
instead of ‘/
’ to avoid confusion
with the select argument, and we used
‘$HOME
’ instead of
‘~
’ because home directory
substitution works at only the beginning of a word.
suffix is used to add a nonstandard suffix
(not space or ‘/
’ for directories)
to completed words.
completes arguments to ‘finger
’ from
the list of users, appends an ‘@
’,
and then completes after the ‘@
’
from the ‘hostnames
’ variable. Note
again the order in which the completions are specified.
Finally, here's a complex example for inspiration:
This completes words following
‘-name
’,
‘-newer
’,
‘-cpio
’, or
‘-ncpio
’ (note the pattern which
matches both) to files, words following
‘-exec
’ or
‘-ok
’ to commands, words following
‘-user
’ and
‘-group
’ to users and groups
respectively and words following
‘-fstype
’ or
‘-type
’ to members of the given
lists. It also completes the switches themselves from the given list (note
the use of ‘c
’-type completion) and
completes anything not otherwise completed to a directory. Whew.
Remember that programmed completions are ignored if the word being completed
is a tilde substitution (beginning with
‘~
’) or a variable (beginning with
‘$
’). See also the
uncomplete builtin command.
- continue
- Continues execution of the nearest enclosing
while or
foreach. The rest of the commands on the
current line are executed.
- default:
- Labels the default case in a
switch statement. It should come after all
case labels.
-
dirs
[-l]
[-n|-v]
-
-
dirs
-S|-L
[filename] (+)
-
-
dirs
-c (+)
- The first form prints the directory stack. The top of the
stack is at the left and the first directory in the stack is the current
directory. With -l,
‘
~
’ or
‘~name
’
in the output is expanded explicitly to home
or the pathname of the home directory for user
name. (+) With
-n, entries are wrapped before they reach the
edge of the screen. (+) With -v, entries are
printed one per line, preceded by their stack positions. (+) If more than
one of -n or -v
is given, -v takes precedence.
-p is accepted but does nothing.
The second form with -S saves the directory
stack to filename as a series of
cd and pushd
commands. The second form with -L sources
filename, which is presumably a directory
stack file saved by the -S option or the
savedirs mechanism. In either case,
dirsfile is used if
filename is not given and
~/.cshdirs is used if
dirsfile is unset.
Note that login shells do the equivalent of
dirs -L
on startup and, if savedirs is set,
dirs -S
before exiting. Because only ~/.tcshrc is
normally sourced before ~/.cshdirs,
dirsfile should be set in
~/.tcshrc rather than
~/.login.
The third form clears the directory stack.
-
echo
[-n]
word ...
- Writes each word to the
shell's standard output, separated by spaces and terminated with a
newline. The echo_style shell variable may be
set to emulate (or not) the flags and escape sequences of the BSD and/or
System V versions of echo(1); see
Escape sequences
(+) and echo(1).
-
echotc
[-sv]
arg ...
(+)
- Exercises the terminal capabilities (see
termcap(5)) in
arg. For example,
echotc home
sends the cursor to the home position,
echotc cm 3 10
sends it to column 3 and row 10, and
echotc ts 0; echo "This is a
test."; echotc fs
prints
This is a test.
in the status line.
If arg is
‘baud
’,
‘cols
’,
‘lines
’,
‘meta
’, or
‘tabs
’, prints the value of that
capability (“yes” or “no” indicating that the
terminal does or does not have that capability). One might use this to
make the output from a shell script less verbose on slow terminals, or
limit command output to the number of lines on the screen:
Termcap strings may contain wildcards which will not echo correctly. One
should use double quotes when setting a shell variable to a terminal
capability string, as in the following example that places the date in the
status line:
With -s, nonexistent capabilities return the
empty string rather than causing an error. With
-v, messages are verbose.
- else
-
- end
-
- endif
-
- endsw
- See the description of the
foreach, if,
switch, and
while statements below.
-
eval
arg ...
- Treats the arguments as input to the shell and executes the
resulting command(s) in the context of the current shell. This is usually
used to execute commands generated as the result of command or variable
substitution, because parsing occurs before these substitutions. See
tset(1) for a sample use of
eval.
-
exec
command ...
- Executes the specified
command in place of the current
shell.
-
exit
[expr]
- The shell exits either with the value of the specified
expr (an expression, as described under
Expressions) or, without
expr, with the value 0.
-
fg
[%job
...]
- Brings the specified jobs (or, without arguments, the
current job) into the foreground, continuing each if it is stopped.
job may be a number, a string,
‘
’,
‘%
’,
‘+
’, or
‘-
’ as described under
Jobs. See also the
run-fg-editor editor command.
-
filetest
-op file
... (+)
- Applies op (which is a
file inquiry operator as described under
File inquiry
operators) to each file and returns
the results as a space-separated list.
-
foreach
name
(wordlist)
-
- ...
-
- end
- Successively sets the variable
name to each member of
wordlist and executes the sequence of
commands between this command and the matching
end. (Both
foreach and end
must appear alone on separate lines.) The builtin command
continue may be used to continue the loop
prematurely and the builtin command break to
terminate it prematurely. When this command is read from the terminal, the
loop is read once prompting with
foreach?
(or prompt2) before any statements in the loop
are executed. If you make a mistake typing in a loop at the terminal you
can rub it out.
-
getspath
(+)
- Prints the system execution path. (TCF only)
-
getxvers
(+)
- Prints the experimental version prefix. (TCF only)
-
glob
word ...
- Like echo, but the
-n parameter is not recognized and words are
delimited by null characters in the output. Useful for programs which wish
to use the shell to filename expand a list of words.
-
goto
word
-
word is filename and
command-substituted to yield a string of the form
‘label’. The shell rewinds
its input as much as possible, searches for a line of the form
label:
possibly preceded by blanks or tabs, and continues execution after that
line.
- hashstat
- Prints a statistics line indicating how effective the
internal hash table has been at locating commands (and avoiding
exec's). An exec
is attempted for each component of the path
where the hash function indicates a possible hit, and in each component
which does not begin with a ‘
/
’.
On machines without vfork(2), prints only the
number and size of hash buckets.
-
history
[-hTr]
[n]
-
-
history
-S|-L|-M
[filename] (+)
-
-
history
-c (+)
- The first form prints the history event list. If
n is given only the
n most recent events are printed or
saved. With -h, the history list is printed
without leading numbers. If -T is specified,
timestamps are printed also in comment form. This can be used to produce
files suitable for loading with
history -L
or
source -h
With -r, the order of printing is most recent
first rather than oldest first.
The second form with -S saves the history list
to filename. If the first word of the
savehist shell variable is set to a number,
at most that many lines are saved. If the second word of
savehist is set to
‘merge
’, the history list is merged
with the existing history file instead of replacing it (if there is one)
and sorted by time stamp. (+) Merging is intended for an environment like
the X Window System with several shells in simultaneous use. If the second
word of savehist is
‘merge
’ and the third word is set to
‘lock
’, the history file update will
be serialized with other shell sessions that would possibly like to merge
history at exactly the same time.
The second form with -L appends
filename (which is presumably a history
list saved by the -S option or the
savehist mechanism) to the history list.
-M is like -L,
but the contents of filename are merged
into the history list and sorted by timestamp. In either case,
histfile is used if
filename is not given and
~/.history is used if
histfile is unset.
Note that
history -L
is exactly like
source -h
except that it does not require a filename.
Note that login shells do the equivalent of
history -L
on startup and, if savehist is set,
history -S
before exiting. Because only ~/.tcshrc is
normally sourced before ~/.history,
histfile should be set in
~/.tcshrc rather than
~/.login.
If histlit is set, the first and second forms
print and save the literal (unexpanded) form of the history list.
The third form clears the history list.
-
hup
[command]
(+)
- With command, runs
command such that it will exit on a
hangup signal and arranges for the shell to send it a hangup signal when
the shell exits. Note that commands may set their own response to hangups,
overriding hup. Without an argument, causes
the non-interactive shell only to exit on a hangup for the remainder of
the script. See also
Signal handling and
the nohup builtin command.
-
if
(expr)
command
- If expr (an expression, as
described under
Expressions) evaluates
true, then command is executed. Variable
substitution on command happens early, at
the same time it does for the rest of the if
command. command must be a simple
command, not an alias, a pipeline, a command list or a parenthesized
command list, but it may have arguments. Input/output redirection occurs
even if expr is false and
command is thus
not executed; this is a bug.
-
if
(expr)
then
-
- ...
-
-
else
if
(expr2)
then
-
- ...
-
- else
-
- ...
-
- endif
- If the specified expr is
true then the commands to the first else are
executed; otherwise if expr2 is true then
the commands to the second else are executed,
etc. Any number of else if pairs are
possible; only one endif is needed. The
else part is likewise optional. (The words
else and endif
must appear at the beginning of input lines; the
if must appear alone on its input line or
after an else.)
-
inlib
shared-library ...
(+)
- Adds each shared-library
to the current environment. There is no way to remove a shared library.
(Domain/OS only)
-
jobs
[-l]
-
-
jobs
-Z
[title]
(+)
- The first form lists the active jobs. With
-l, lists process IDs in addition to the
normal information. On TCF systems, prints the site on which each job is
executing.
The second form with the -Z option sets the
process title to title using
setproctitle(3) where available. If no
title is provided, the process title will
be cleared.
-
kill
-l
-
-
kill
[-s
signal]
%job|pid
...
- The first form lists the signal names.
The second form sends the specified signal
(or, if none is given, the TERM (terminate) signal) to the specified jobs
or processes. job may be a number, a
string, ‘
’,
‘%
’,
‘+
’, or
‘-
’ as described under
Jobs. Signals are either given
by number or by name (as given in
/usr/include/signal.h, stripped of the prefix
‘SIG’).
There is no default job; entering just
kill
does not send a signal to the current job. If the signal being sent is TERM
(terminate) or HUP (hangup), then the job or process is sent a CONT
(continue) signal as well.
-
limit
[-h]
[resource
[maximum-use]]
- Limits the consumption by the current process and each
process it creates to not individually exceed
maximum-use on the specified
resource.
If no maximum-use is given, then the
current limit for resource is printed.
If no resource is given, then all
limitations are given.
If the -h flag is given, the hard limits are
used instead of the current limits. The hard limits impose a ceiling on
the values of the current limits. Only the super-user may raise the hard
limits, but a user may lower or raise the current limits within the legal
range.
Controllable resource types currently
include (if supported by the OS):
maximum-use may be given as a (floating
point or integer) number followed by a scale factor. For all limits other
than cputime the default scale is
‘
k
’ or
‘kilobytes
’ (1024 bytes); a scale
factor of ‘m
’ or
‘megabytes
’ (1048576 bytes) or
‘g
’ or
‘gigabytes
’ (1073741824 bytes) may
also be used. For cputime the default scaling
is ‘seconds
’, while
‘m
’ for minutes or
‘h
’ for hours, or a time of the form
‘mm:
ss’
giving minutes and seconds may be used.
If maximum-use is
‘unlimited
’, then the limitation on
the specified resource is removed (this
is equivalent to the unlimit builtin
command).
For both resource names and scale factors,
unambiguous prefixes of the names suffice.
-
log
(+)
- Prints the watch shell
variable and reports on each user indicated in
watch who is logged in, regardless of when
they last logged in. See also watchlog.
- login
- Terminates a login shell, replacing it with an instance of
/bin/login. This is one way to log off,
included for compatibility with sh(1).
- logout
- Terminates a login shell. Especially useful if
ignoreeof is set.
-
ls-F
[-switch
...]
[file
...] (+)
- Lists files like
ls -F
but much faster.
ls-F identifies each type of special file in
the listing with a special character suffix:
If the listlinks shell variable is set,
symbolic links are identified in more detail (on only systems that have
them, of course):
listlinks also slows down
ls-F and causes partitions holding files
pointed to by symbolic links to be mounted.
If the listflags shell variable is set to
‘x
’,
‘a
’, or
‘A
’, or any combination thereof
(e.g., ‘xA
’), they are used as flags
to ls-F, making it act like
or a combination, for example
ls -FxA
On machines where
ls -C
is not the default, ls-F acts like
ls -CF
unless listflags contains an
‘x
’, in which case it acts like
ls -xF
ls-F passes its arguments to
ls(1) if it is given any switches, so
alias ls ls-F
generally does the right thing.
The ls-F builtin can list files using different
colors depending on the filetype or extension. See the
color shell variable and the
LS_COLORS
environment variable.
-
migrate
[-site]
pid|%jobid
... (+)
-
-
migrate
-site
(+)
- The first form migrates the process or job to the site
specified or the default site determined by the system path. (TCF only)
The second form is equivalent to
migrate
-site
$$
in that it migrates the current process to the specified site. Migrating the
shell itself can cause unexpected behavior, because the shell does not
like to lose its tty. (TCF only)
-
newgrp
[-]
[group]
(+)
- Equivalent to
exec newgrp
as per newgrp(1). Available only if the shell
was so compiled; see the version shell
variable.
-
nice
[+number]
[command]
- Sets the scheduling priority for the shell to
number, or, without
number, to 4. With
command, runs
command at the appropriate priority. The
greater the number, the less cpu the
process gets. The super-user may specify negative priority by using
nice
-number
...
command is always executed in a sub-shell,
and the restrictions placed on commands in simple
if statements apply.
-
nohup
[command]
- With command, runs
command such that it will ignore hangup
signals. Note that commands may set their own response to hangups,
overriding nohup.
Without an argument, causes the non-interactive shell only to ignore hangups
for the remainder of the script. See also
Signal handling and
the hup builtin command.
-
notify
[%job
...]
- Causes the shell to notify the user asynchronously when the
status of any of the specified jobs (or, without
%job, the
current job) changes, instead of waiting until the next prompt as is
usual. job may be a number, a string,
‘
’,
‘%
’,
‘+
’, or
‘-
’ as described under
Jobs. See also the
notify shell variable.
-
onintr
[-|label]
- Controls the action of the shell on interrupts. Without
arguments, restores the default action of the shell on interrupts, which
is to terminate shell scripts or to return to the terminal command input
level.
With ‘
-
’, causes all interrupts to be
ignored.
With label, causes the shell to execute a
goto
label
when an interrupt is received or a child process terminates because it was
interrupted.
onintr is ignored if the shell is running
detached and in system startup files (see
FILES), where interrupts are
disabled anyway.
-
popd
[-p]
[-l]
[-n|-v]
[+n]
- Without arguments, pops the directory stack and returns to
the new top directory.
With a number
‘
+n
’,
discards the nth entry in the stack.
Finally, all forms of popd print the final
directory stack, just like dirs. The
pushdsilent shell variable can be set to
prevent this and the -p flag can be given to
override pushdsilent. The
-l, -n, and
-v flags have the same effect on
popd as on dirs.
(+)
-
printenv
[name]
(+)
- Prints the names and values of all environment variables
or, with name, the value of the
environment variable name.
-
pushd
[-p]
[-l]
[-n|-v]
[name|+n]
- Without arguments, exchanges the top two elements of the
directory stack. If pushdtohome is set,
pushd without arguments acts as
pushd ~
like cd. (+)
With name, pushes the current working
directory onto the directory stack and changes to
name. If
name is
‘-
’ it is interpreted as the
previous working directory (see
Filename
substitution). (+) If dunique is set,
pushd removes any instances of
name from the stack before pushing it
onto the stack. (+)
With a number
‘+n
’,
rotates the nth element of the directory
stack around to be the top element and changes to it. If
dextract is set, however,
pushd
+n
extracts the nth directory, pushes it onto
the top of the stack and changes to it. (+)
Finally, all forms of pushd print the final
directory stack, just like dirs. The
pushdsilent shell variable can be set to
prevent this and the -p flag can be given to
override pushdsilent. The
-l, -n, and
-v flags have the same effect on
pushd as on
dirs. (+)
- rehash
- Causes the internal hash table of the contents of the
directories in the path variable to be
recomputed. This is needed if the autorehash
shell variable is not set and new commands are added to directories in
path while you are logged in. With
autorehash, a new command will be found
automatically, except in the special case where another command of the
same name which is located in a different directory already exists in the
hash table. Also flushes the cache of home directories built by tilde
expansion.
-
repeat
count
command
- The specified command,
which is subject to the same restrictions as the
command in the one line
if statement above, is executed
count times. I/O redirections occur
exactly once, even if count is 0.
-
rootnode
//nodename
(+)
- Changes the rootnode to
//nodename,
so that ‘
/
’ will be interpreted as
‘//nodename
’.
(Domain/OS only)
-
sched
(+)
-
-
sched
[+]hh:mm
command (+)
-
-
sched
-n
(+)
- The first form prints the scheduled-event list. The
sched shell variable may be set to define the
format in which the scheduled-event list is printed.
The second form adds command to the
scheduled-event list. For example,
causes the shell to echo
It's eleven o'clock.
at 11 AM.
The time may be in 12-hour AM/PM format
or may be relative to the current time:
A relative time specification may not use AM/PM format.
The third form removes item n from the
event list:
A command in the scheduled-event list is executed just before the first
prompt is printed after the time when the command is scheduled. It is
possible to miss the exact time when the command is to be run, but an
overdue command will execute at the next prompt. A command which comes due
while the shell is waiting for user input is executed immediately.
However, normal operation of an already-running command will not be
interrupted so that a scheduled-event list element may be run.
This mechanism is similar to, but not the same as, the
at(1) command on some Unix systems. Its major
disadvantage is that it may not run a command at exactly the specified
time. Its major advantage is that because
sched runs directly from the shell, it has
access to shell variables and other structures. This provides a mechanism
for changing one's working environment based on the time of day.
- set
-
-
set
name ...
-
-
set
name=word
...
-
-
set
[-r]
[-f|-l]
name=(wordlist)
... (+)
-
-
set
name[index]=word
...
-
-
set
-r (+)
-
-
set
-r name
... (+)
-
-
set
-r
name=word
... (+)
- The first form of the command prints the value of all shell
variables. Variables which contain more than a single word print as a
parenthesized word list.
The second form sets name to the null
string.
The third form sets name to the single
word.
The fourth form sets name to the list of
words in wordlist.
In all cases the value is command and filename expanded. If
-r is specified, the value is set read-only.
If -f or -l are
specified, set only unique words keeping their order.
-f prefers the first occurrence of a word,
and -l the last.
The fifth form sets the index'th component
of name to
word; this component must already exist.
The sixth form lists only the names of all shell variables that are
read-only.
The seventh form makes name read-only,
whether or not it has a value.
The eighth form is the same as the third form, but make
name read-only at the same time.
These arguments can be repeated to set and/or make read-only multiple
variables in a single set command. Note, however, that variable expansion
happens for all arguments before any setting occurs. Note also that
‘
=
’ can be adjacent to both
name and
word or separated from both by
whitespace, but cannot be adjacent to only one or the other. See also the
unset builtin command.
-
setenv
[name
[value]]
- Without arguments, prints the names and values of all
environment variables.
With name, sets the environment variable
name to
value or, without
value, to the null string.
-
setpath
path (+)
- Equivalent to setpath(1).
(Mach only)
-
setspath
LOCAL|site|cpu
... (+)
- Sets the system execution path. (TCF only)
-
settc
cap value (+)
- Tells the shell to believe that the terminal capability
cap (as defined in
termcap(5)) has the value
value. No sanity checking is done.
Concept terminal users may have to
settc xn no
to get proper wrapping at the rightmost column.
-
setty
[-d|-q|-x]
[-a]
[[+|-]mode]
(+)
- Controls which tty modes (see
Terminal
management (+)) the shell does not allow to change.
-d, -q, or
-x tells setty
to act on the ‘edit’, ‘quote’, or
‘execute’ set of tty modes respectively; without
-d, -q, or
-x, ‘execute’ is used.
Without other arguments, setty lists the modes
in the chosen set which are fixed on
(‘+mode’)
or off
(‘-mode’).
The available modes, and thus the display, vary from system to system.
With -a, lists all tty modes in the chosen
set whether or not they are fixed. With
+mode,
-mode, or
mode, fixes
mode on or off or removes control from
mode in the chosen set. For example,
setty +echok echoe
fixes ‘echok
’ mode on and allows
commands to turn ‘echoe
’ mode on or
off, both when the shell is executing commands.
-
setxvers
[string]
(+)
- Set the experimental version prefix to
string, or removes it if
string is omitted. (TCF only)
-
shift
[variable]
- Without arguments, discards
argv[1] and shifts the members of
argv to the left. It is an error for
argv not to be set or to have less than one
word as value.
With variable, performs the same function
on variable.
-
source
[-h]
name
[args
...]
- The shell reads and executes commands from
name. The commands are not placed on the
history list. If any args are given, they
are placed in argv. (+)
source commands may be nested; if they are
nested too deeply the shell may run out of file descriptors. An error in a
source at any level terminates all nested
source commands.
With -h, commands are placed on the history
list instead of being executed, much like
history -L
-
stop
%job|pid
...
- Stops the specified jobs or processes which are executing
in the background. job may be a number, a
string, ‘
’,
‘%
’,
‘+
’, or
‘-
’ as described under
Jobs.
There is no default job; entering just
stop
does not stop the current job.
- suspend
- Causes the shell to stop in its tracks, much as if it had
been sent a stop signal with ^Z. This is most
often used to stop shells started by
su(1).
-
switch
(string)
-
-
case
str1:
-
- ...
-
- breaksw
-
- ...
-
- default:
-
- ...
-
- breaksw
-
- endsw
- Each case label is successively matched, against the
specified string which is first command
and filename expanded. The file metacharacters
‘
*
’,
‘?
’, and
‘[...]
’ may be used in the case
labels, which are variable expanded. If none of the labels match before a
default label is found, then the execution
begins after the default label. Each case
label and the default label must appear at
the beginning of a line. The command breaksw
causes execution to continue after the endsw.
Otherwise control may fall through case labels and default labels as in C.
If no label matches and there is no default, execution continues after the
endsw.
-
telltc
(+)
- Lists the values of all terminal capabilities (see
termcap(5)).
-
termname
[termtype]
(+)
- Tests if termtype (or the
current value of
TERM
if no
termtype is given) has an entry in the
hosts termcap(5) or
terminfo(5) database. Prints the terminal
type to stdout and returns 0 if an entry is present otherwise returns
1.
-
time
[command]
- Executes command (which
must be a simple command, not an alias, a pipeline, a command list or a
parenthesized command list) and prints a time summary as described under
the time variable. If necessary, an extra
shell is created to print the time statistic when the command completes.
Without command, prints a time summary for
the current shell and its children.
-
umask
[value]
- Sets the file creation mask to
value, which is given in octal. Common
values for the mask are 002, giving all access to the group and read and
execute access to others, and 022, giving read and execute access to the
group and others.
Without value, prints the current file
creation mask.
-
unalias
pattern
- Removes all aliases whose names match
pattern. Thus
unalias *
removes all aliases. It is not an error for nothing to be
unaliased.
-
uncomplete
pattern (+)
- Removes all completions whose names match
pattern. Thus
uncomplete *
removes all completions. It is not an error for nothing to be
uncompleted.
- unhash
- Disables use of the internal hash table to speed location
of executed programs.
-
universe
universe (+)
- Sets the universe to
universe. (Masscomp/RTU only)
-
unlimit
[-hf]
[resource]
- Removes the limitation on
resource or, if no
resource is specified, all
resource limitations.
With -h, the corresponding hard limits are
removed. Only the super-user may do this.
Note that unlimit may not exit successful,
since most systems do not allow descriptors
to be unlimited.
With -f errors are ignored.
-
unset
pattern
- Removes all variables whose names match
pattern, unless they are read-only. Thus
unset *
removes all variables unless they are read-only; this is a bad idea.
It is not an error for nothing to be
unset.
-
unsetenv
pattern
- Removes all environment variables whose names match
pattern. Thus
unsetenv *
removes all environment variables; this is a bad idea.
It is not an error for nothing to be
unsetenved.
-
ver
[systype
[command]]
(+)
- Without arguments, prints
SYSTYPE
.
With systype, sets
SYSTYPE
to
systype.
With systype and
command, executes
command under
systype.
systype may be
‘bsd4.3
’ or
‘sys5.3
’.
(Domain/OS only)
- wait
- The shell waits for all background jobs. If the shell is
interactive, an interrupt will disrupt the wait and cause the shell to
print the names and job numbers of all outstanding jobs.
-
warp
universe (+)
- Sets the universe to
universe. (Convex/OS only)
-
watchlog
(+)
- An alternate name for the log
builtin command. Available only if the shell was so compiled; see the
version shell variable.
-
where
command (+)
- Reports all known instances of
command, including aliases, builtins and
executables in path.
-
which
command (+)
- Displays the command that will be executed by the shell
after substitutions, path searching, etc. The
builtin command is just like which(1), but it
correctly reports tcsh aliases and builtins
and is 10 to 100 times faster. See also the
which-command editor command.
-
while
(expr)
-
- ...
-
- end
- Executes the commands between the
while and the matching
end while
expr (an expression, as described under
Expressions) evaluates
non-zero. while and
end must appear alone on their input lines.
break and
continue may be used to terminate or continue
the loop prematurely. If the input is a terminal, the user is prompted the
first time through the loop as with
foreach.
If set, each of these aliases executes automatically at the indicated time. They
are all initially undefined.
Supported special aliases are:
- beepcmd
- Runs when the shell wants to ring the terminal bell.
- cwdcmd
- Runs after every change of working directory. For example,
if the user is working on an X window system using
xterm(1) and a re-parenting window manager
that supports title bars such as twm(1) and
does
then the shell will change the title of the running
xterm(1) to be the name of the host, a colon,
and the full current working directory. A fancier way to do that is
This will put the hostname and working directory on the title bar but only
the hostname in the icon manager menu.
Note that putting a cd,
pushd, or popd
in cwdcmd may cause an infinite loop. It is
the author's opinion that anyone doing so will get what they deserve.
- jobcmd
- Runs before each command gets executed, or when the command
changes state. This is similar to postcmd,
but it does not print builtins.
then executing
vi foo.c
will put the command string in the xterm title bar.
- helpcommand
- Invoked by the run-help editor
command. The command name for which help is sought is passed as sole
argument. For example, if one does
then the help display of the command itself will be invoked, using the GNU
help calling convention.
Currently there is no easy way to account for various calling conventions
(e.g., the customary Unix ‘
-h
’),
except by using a table of many commands.
- periodic
- Runs every tperiod minutes.
This provides a convenient means for checking on common but infrequent
changes such as new mail. For example, if one does
then the checknews(1) program runs every 30
minutes.
If periodic is set but
tperiod is unset or set to 0,
periodic behaves like
precmd.
- precmd
- Runs just before each prompt is printed. For example, if
one does
then date(1) runs just before the shell prompts
for each command.
There are no limits on what precmd can be set
to do, but discretion should be used.
- postcmd
- Runs before each command gets executed.
then executing
vi foo.c
will put the command string in the xterm title bar.
- shell
- Specifies the interpreter for executable scripts which do
not themselves specify an interpreter. The first word should be a full
path name to the desired interpreter (e.g.,
‘
/bin/csh
’ or
‘/usr/local/bin/tcsh
’).
The variables described in this section have special meaning to the shell.
The shell sets
addsuffix,
argv,
autologout,
csubstnonl,
command,
echo_style,
edit,
gid,
group,
home,
loginsh,
oid,
path,
prompt,
prompt2,
prompt3,
shell,
shlvl,
tcsh,
term,
tty,
uid,
user, and
version at startup; they do not change thereafter
unless changed by the user. The shell updates
cwd,
dirstack,
owd, and
status when
necessary, and sets
logout on logout.
The shell synchronizes
group,
home,
path,
shlvl,
term, and
user with the environment variables of the same
names: whenever the environment variable changes the shell changes the
corresponding shell variable to match (unless the shell variable is read-only)
and vice versa. Note that although
cwd and
PWD
have identical meanings, they are not
synchronized in this manner, and that the shell automatically converts between
the different formats of
path and
PATH
.
Supported special shell variables are:
-
addsuffix
(+)
- If set, filename completion adds
‘
/
’ to the end of directories and a
space to the end of normal files when they are matched exactly. Set by
default.
-
afsuser
(+)
- If set, autologout's autolock
feature uses its value instead of the local username for kerberos
authentication.
-
ampm
(+)
- If set, all times are shown in 12-hour AM/PM format.
-
anyerror
(+)
- This variable selects what is propagated to the value of
the status variable. For more information see
the description of the status variable
below.
- argv
- The arguments to the shell. Positional parameters are taken
from argv, i.e.,
‘
$1
’ is replaced by
‘$argv[1]
’, etc. Set by default, but
usually empty in interactive shells.
-
autocorrect
(+)
- If set, the spell-word editor
command is invoked automatically before each completion attempt.
-
autoexpand
(+)
- If set, the expand-history
editor command is invoked automatically before each completion attempt.
If this is set to ‘
onlyhistory
’, then
only history will be expanded and a second completion will expand
filenames.
-
autolist
(+)
- If set, possibilities are listed after an ambiguous
completion.
If set to ‘
ambiguous
’, possibilities
are listed only when no new characters are added by completion.
-
autologout
(+)
- The first word is the number of minutes of inactivity
before automatic logout. The optional second word is the number of minutes
of inactivity before automatic locking. When the shell automatically logs
out, it prints
auto-logout
sets the variable logout to
‘automatic
’ and exits. When the
shell automatically locks, the user is required to enter their password to
continue working. Five incorrect attempts result in automatic logout.
Set to ‘60
’ (automatic logout after 60
minutes, and no locking) by default in login and superuser shells, but not
if the shell thinks it is running under a window system (i.e., the
DISPLAY
environment variable is set),
the tty is a pseudo-tty (pty) or the shell was not so compiled (see the
version shell variable).
Unset autologout or set it to
‘0
’ to disable automatic logout. See
also the afsuser and
logout shell variables.
-
autorehash
(+)
- If set, the internal hash table of the contents of the
directories in the path variable will be
recomputed if a command is not found in the hash table. In addition, the
list of available commands will be rebuilt for each command completion or
spelling correction attempt if set to
‘
complete
’ or
‘correct
’ respectively; if set to
‘always
’, this will be done for both
cases.
-
backslash_quote
(+)
- If set, backslashes (`\') always quote
‘
\
’,
‘'
’, and
‘"
’. This may make complex
quoting tasks easier, but it can cause syntax errors in
csh(1) scripts.
- catalog
- The file name of the message catalog. If set,
tcsh uses
tcsh.${catalog} as a message catalog instead
of default tcsh.
- cdpath
- A list of directories in which
cd should search for subdirectories if they
aren't found in the current directory.
-
cdtohome
(+)
- If not set, cd requires a
directory name, and will not go to the
home directory if it's omitted. This is set
by default.
- color
- If set, it enables color display for the builtin
ls-F and it passes
--color=auto to
ls(1). Alternatively, it can be set to only
‘
ls-F
’ or only
‘ls
’ to enable color to only one
command. Setting it to nothing is equivalent to setting it to
‘(ls-F ls)
’.
- colorcat
- If set, it enables color escape sequence for NLS message
files, and display colorful NLS messages.
-
command
(+)
- If set, the command which was passed to the shell with the
-c flag.
-
compat_expr
(+)
- If set, the shell will evaluate expressions right to left,
like the original csh(1).
-
complete
(+)
- If set to ‘
igncase
’,
the completion becomes case insensitive.
If set to ‘enhance
’, completion
ignores case and considers hyphens and underscores to be equivalent; it
will also treat periods, hyphens and underscores
(‘.
’,
‘-
’, and
‘_
’) as word separators.
If set to ‘Enhance
’, completion
matches uppercase and underscore characters explicitly and matches
lowercase and hyphens in a case-insensitive manner; it will treat periods,
hyphens and underscores as word separators.
-
continue
(+)
- If set to a list of commands, the shell will continue the
listed commands, instead of starting a new one.
-
continue_args
(+)
- Same as continue, but the shell will execute:
-
correct
(+)
- If set to ‘
cmd
’,
commands are automatically spelling-corrected.
If set to ‘complete
’, commands are
automatically completed.
If set to ‘all
’, the entire command
line is corrected.
-
csubstnonl
(+)
- If set, newlines and carriage returns in command
substitution are replaced by spaces. Set by default.
- cwd
- The full pathname of the current directory. See also the
dirstack and owd
shell variables.
-
(+)
- If set,
pushd
+n
extracts the nth directory from the
directory stack rather than rotating it to the top.
-
dirsfile
(+)
- The default location in which
dirs -S
and
dirs -L
look for a history file. If unset, ~/.cshdirs
is used. Because only ~/.tcshrc is normally
sourced before ~/.cshdirs,
dirsfile should be set in
~/.tcshrc rather than
~/.login.
-
dirstack
(+)
- An array of all the directories on the directory stack.
‘$dirstack[1]’ is the current working directory,
‘$dirstack[2]’ the first directory on the stack, etc. Note
that the current working directory is ‘$dirstack[1]’ but
‘
=0
’ in directory stack
substitutions, etc. One can change the stack arbitrarily by setting
dirstack, but the first element (the current
working directory) is always correct. See also the
cwd and owd
shell variables.
-
dspmbyte
(+)
- Has an effect only if
‘
dspm
’ is listed as part of the
version shell variable.
If set to ‘euc
’, it enables display
and editing EUC-kanji(Japanese) code.
If set to ‘sjis
’, it enables display
and editing Shift-JIS(Japanese) code.
If set to ‘big5
’, it enables display
and editing Big5(Chinese) code.
If set to ‘utf8
’, it enables display
and editing Utf8(Unicode) code.
If set to exactly 256 characters in the
following format, it enables display and editing of original multi-byte
code format:
> set dspmbyte =
NNN...[250
characters]...NNN
Each character N in the 256 character value
corresponds (from left to right) to the ASCII codes 0x00, 0x01, 0x02, ...,
0xfd, 0xfe, 0xff at the same index. Each character is set to number 0, 1,
2 or 3, with the meaning:
For example, if set to 256 characters starting with
‘001322
’, the value is interpreted
as:
Character |
ASCII |
Multi-byte character
use
|
0 |
0x00 |
Not used. |
0 |
0x01 |
Not used. |
1 |
0x02 |
First byte. |
3 |
0x03 |
First byte and second byte. |
2 |
0x04 |
Second byte. |
2 |
0x05 |
Second byte. |
The GNU fileutils version of ls cannot display multi-byte filenames without
the -N
(--literal) option. If you are using this
version, set the second word of dspmbyte to
‘ls
’. If not, for example,
ls-F -l
cannot display multi-byte filenames.
Note that this variable can only be used if KANJI and DSPMBYTE has been
defined at compile time.
-
dunique
(+)
- If set, pushd removes any
instances of name from the stack before
pushing it onto the stack.
- echo
- If set, each command with its arguments is echoed just
before it is executed. For non-builtin commands all expansions occur
before echoing. Builtin commands are echoed before command and filename
substitution, because these substitutions are then done selectively. Set
by the -x command line option.
-
echo_style
(+)
- The style of the echo builtin.
May be set to:
Set by default to the local system default. The BSD and System V options are
described in the echo(1) man pages on the
appropriate systems.
-
edit
(+)
- If set, the command-line editor is used. Set by default in
interactive shells.
-
editors
(+)
- A list of command names for the
run-fg-editor editor command to match. If not
set, the
EDITOR
(‘ed
’ if unset) and
VISUAL
(‘vi
’ if unset) environment
variables will be used instead.
-
ellipsis
(+)
- If set, the ‘
%c
’,
‘%.
’, and
‘%C
’ prompt sequences (see the
prompt shell variable) indicate skipped
directories with an ellipsis (‘...
’)
instead of
‘/<skipped>
’.
-
euid
(+)
- The user's effective user ID.
-
euser
(+)
- The first matching passwd entry name corresponding to the
effective user ID.
-
fignore
(+)
- Lists file name suffixes to be ignored by completion.
- filec
- In tcsh, completion is always
used and this variable is ignored by default.
If edit is unset, then the traditional
csh(1) completion is used.
If set in csh(1), filename completion is
used.
-
gid
(+)
- The user's real group ID.
-
globdot
(+)
- If set, wild-card glob patterns will match files and
directories beginning with ‘
.
’
except for ‘.’ and
‘..’.
-
globstar
(+)
- If set, the ‘
**
’ and
‘***
’ file glob patterns will match
any string of characters including
‘/
’ traversing any existing
sub-directories. For example,
ls **.c
will list all the .c files in the current directory tree.
If used by itself, it will match zero or more sub-directories. For example,
ls /usr/include/**/time.h
will list any file named ‘time.h
’ in
the /usr/include directory tree; whereas
ls /usr/include/**time.h
will match any file in the /usr/include
directory tree ending in ‘time.h
’.
To prevent problems with recursion, the
‘**
’ glob-pattern will not descend
into a symbolic link containing a directory. To override this, use
‘***
’.
-
group
(+)
- The user's group name.
- highlight
- If set, the incremental search match (in
i-search-back and
i-search-fwd) and the region between the mark
and the cursor are highlighted in reverse video.
Highlighting requires more frequent terminal writes, which introduces extra
overhead. If you care about terminal performance, you may want to leave
this unset.
- histchars
- A string value determining the characters used in
History
substitution.
The first character of its value is used as the history substitution
character, replacing the default character
‘
!
’.
The second character of its value replaces the character
‘^
’ in quick substitutions.
-
histdup
(+)
- Controls handling of duplicate entries in the history list.
If set to ‘
all
’ only unique history
events are entered in the history list.
If set to ‘prev
’ and the last history
event is the same as the current command, then the current command is not
entered in the history.
If set to ‘erase
’ and the same event
is found in the history list, that old event gets erased and the current
one gets inserted.
Note that the ‘prev
’ and
‘all
’ options renumber history
events so there are no gaps.
-
histfile
(+)
- The default location in which
history -S
and
history -L
look for a history file.
If unset, ~/.history is used.
histfile is useful when sharing the same home
directory between different machines, or when saving separate histories on
different terminals. Because only ~/.tcshrc
is normally sourced before ~/.history,
histfile should be set in
~/.tcshrc rather than
~/.login.
-
histlit
(+)
- If set, builtin and editor commands and the
savehist mechanism use the literal
(unexpanded) form of lines in the history list. See also the
toggle-literal-history editor command.
- history
- The first word indicates the number of history events to
save.
The optional second word (+) indicates the format in which history is
printed; if not given,
‘
%h\t%T\t%R\n
’ is used. The format
sequences are described below under prompt;
note the variable meaning of ‘%R
’.
Set to ‘100
’ by default.
- home
- Initialized to the home directory of the invoker. The
filename expansion of ‘
~
’ refers to
this variable.
- ignoreeof
- If set to the empty string or
‘
0
’ and the input device is a
terminal, the end-of-file command (usually
generated by the user by typing ^D on an
empty line) causes the shell to print
Use "exit" to leave
tcsh.
instead of exiting. This prevents the shell from accidentally being killed.
Historically this setting exited after 26 successive EOF's to avoid
infinite loops.
If set to a number ‘n’, the shell
ignores n - 1 consecutive
end-of-files and exits on the
nth (+).
If unset, ‘1
’ is used, i.e., the shell
exits on a single ^D.
-
implicitcd
(+)
- If set, the shell treats a directory name typed as a
command as though it were a request to change to that directory.
If set to verbose, the change of directory is
echoed to the standard output.
This behavior is inhibited in non-interactive shell scripts, or for command
strings with more than one word. Changing directory takes precedence over
executing a like-named command, but it is done after alias substitutions.
Tilde and variable expansions work as expected.
-
inputmode
(+)
- If set to ‘
insert
’ or
‘overwrite
’, puts the editor into
that input mode at the beginning of each line.
-
killdup
(+)
- Controls handling of duplicate entries in the kill ring.
If set to ‘
all
’ only unique strings
are entered in the kill ring.
If set to ‘prev
’ and the last killed
string is the same as the current killed string, then the current string
is not entered in the ring.
If set to ‘erase
’ and the same string
is found in the kill ring, the old string is erased and the current one is
inserted.
-
killring
(+)
- Indicates the number of killed strings to keep in memory.
Set to ‘
30
’ by default.
If unset or set to less than ‘2
’, the
shell will only keep the most recently killed string.
Strings are put in the killring by the editor commands that delete (kill)
strings of text, e.g. backward-delete-word,
kill-line, etc, as well as the
copy-region-as-kill command. The
yank editor command will yank the most
recently killed string into the command-line, while
yank-pop (see
Editor commands
(+)) can be used to yank earlier killed strings.
-
listflags
(+)
- If set to ‘
x
’,
‘a
’, or
‘A
’, or any combination thereof
(e.g., ‘xA
’), they are used as flags
to ls-F, making it act like
or a combination, for example
ls -FxA
If the first word contains ‘a
’, shows
all files (even if they start with a
‘.
’).
If the first word contains ‘A
’, shows
all files but ‘.
’ and
‘..
’.
If the first word contains ‘x
’, sorts
across instead of down.
If the second word of listflags is set, it is
used as the path to ls(1).
-
listjobs
(+)
- If set, all jobs are listed when a job is suspended.
If set to ‘
long
’, the listing is in
long format.
-
listlinks
(+)
- If set, the ls-F builtin
command shows the type of file to which each symbolic link points.
-
listmax
(+)
- The maximum number of items which the
list-choices editor command will list without
asking first.
-
listmaxrows
(+)
- The maximum number of rows of items which the
list-choices editor command will list without
asking first.
-
loginsh
(+)
- Set by the shell if it is a login shell. Setting or
unsetting it within a shell has no effect. See also
shlvl.
-
logout
(+)
- Set by the shell to
‘
normal
’ before a normal logout,
‘automatic
’ before an automatic
logout, and ‘hangup
’ if the shell
was killed by a hangup signal (see
Signal handling). See
also the autologout shell variable.
- mail
- A list of files and directories to check for incoming mail,
optionally preceded by a numeric word. Before each prompt, if 10 minutes
have passed since the last check, the shell checks each file and displays
You have new mail.
(or, if mail contains multiple files,
You have new mail in
name.)
if the filesize is greater than zero in size and has a modification time
greater than its access time.
If you are in a login shell, then no mail file is reported unless it has
been modified after the time the shell has started up, to prevent
redundant notifications. Most login programs will tell you whether or not
you have mail when you log in.
If a file specified in mail is a directory, the
shell will count each file within that directory as a separate message,
and will report
You have n
mails.
or
You have n
mails in
name.
as appropriate. This functionality is provided primarily for those systems
which store mail in this manner, such as the Andrew Mail System.
If the first word of mail is numeric it is
taken as a different mail checking interval, in seconds.
Under very rare circumstances, the shell may report
You have mail.
instead of
You have new mail.
-
matchbeep
(+)
- If set to ‘
never
’,
completion never beeps.
If set to ‘nomatch
’, it beeps only
when there is no match.
If set to ‘ambiguous
’, it beeps when
there are multiple matches.
If set to ‘notunique
’, it beeps when
there is one exact and other longer matches.
If unset, ‘ambiguous
’ is used.
-
nobeep
(+)
- If set, beeping is completely disabled. See also
visiblebell.
- noclobber
- If set, restrictions are placed on output redirection to
insure that files are not accidentally destroyed and that
‘
>>
’ redirections refer to
existing files, as described in the
Input/output section.
If contains ‘ask
’, an interacive
confirmation is presented, rather than an error.
If contains ‘notempty
’,
‘>
’ is allowed on empty
files.
- noding
- If set, disable the printing of
DING!
in the prompt time specifiers at the change of
hour.
- noglob
- If set,
Filename
substitution and
Directory
stack substitution (+) are inhibited. This is most useful in shell
scripts which do not deal with filenames, or after a list of filenames has
been obtained and further expansions are not desirable.
-
nokanji
(+)
- If set and the shell supports Kanji (see the
version shell variable), it is disabled so
that the meta key can be used.
- nonomatch
- If set, a
Filename
substitution or
Directory
stack substitution (+) which does not match any existing files is left
untouched rather than causing an error. It is still an error for the
substitution to be malformed. For example,
echo [
still gives an error.
-
nostat
(+)
- A list of directories (or glob-patterns which match
directories; see
Filename
substitution) that should not be
stat(2)ed during a completion operation. This
is usually used to exclude directories which take too much time to
stat(2), for example
/afs.
- notify
- If set, the shell announces job completions asynchronously.
The default is to present job completions just before printing a
prompt.
-
oid
(+)
- The user's real organization ID. (Domain/OS only)
-
owd
(+)
- The old working directory, equivalent to the
‘
-
’ used by
cd and pushd.
See also the cwd and
dirstack shell variables.
- padhour
- If set, enable the printing of padding '0' for hours, in 24
and 12 hour formats. E.g., ‘07:45:42’ versus
‘7:45:42’.
- parseoctal
- To retain compatibily with older versions numeric variables
starting with 0 are not interpreted as octal. Setting this variable
enables proper octal parsing.
- path
- A list of directories in which to look for executable
commands.
A null word specifies the current directory.
If there is no path variable then only full
path names will execute.
path is set by the shell at startup from the
PATH
environment variable or, if
PATH
does not exist, to a
system-dependent default, such as
(/usr/local/bin /usr/bsd /bin /usr/bin
.)
The shell may put ‘.
’ first or last in
path or omit it entirely depending on how it
was compiled; see the version shell variable.
A shell which is given neither the -c nor the
-t option hashes the contents of the
directories in path after reading
~/.tcshrc and each time
path is reset.
If one adds a new command to a directory in
path while the shell is active, one may need
to do a rehash for the shell to find it.
-
printexitvalue
(+)
- If set and an interactive program exits with a non-zero
status, the shell prints
Exit
status
- prompt
- The string which is printed before reading each command
from the terminal.
prompt may include any of the following
formatting sequences (+), which are replaced by the given information:
‘
%B
’,
‘%S
’,
‘%U
’, and
‘%{string%}
’
are available in only eight-bit-clean shells; see the
version shell variable.
The bold, standout and underline sequences are often used to distinguish a
superuser shell. For example,
If ‘%t
’,
‘%@
’,
‘%T
’,
‘%p
’, or
‘%P
’ is used, and
noding is not set, then print
DING!
on the change of hour (i.e, ‘:00’ minutes) instead of the
actual time.
Set by default to ‘%#
’ in
interactive shells.
-
prompt2
(+)
- The string with which to prompt in
while and
foreach loops and after lines ending in
‘
\
’. The same format sequences may
be used as in prompt; note the variable
meaning of ‘%R
’.
Set by default to ‘%R?
’ in
interactive shells.
-
prompt3
(+)
- The string with which to prompt when confirming automatic
spelling correction. The same format sequences may be used as in
prompt; note the variable meaning of
‘
%R
’.
Set by default to ‘CORRECT>%R
(y|n|e|a)?
’ in interactive shells.
-
promptchars
(+)
- If set (to a two-character string), the
‘
%#
’ formatting sequence in the
prompt shell variable is replaced with the
first character for normal users and the second character for the
superuser.
-
pushdtohome
(+)
- If set, pushd without
arguments does
pushd ~
like cd.
-
pushdsilent
(+)
- If set, pushd and
popd do not print the directory stack.
-
recexact
(+)
- If set, completion completes on an exact match even if a
longer match is possible.
-
recognize_only_executables
(+)
- If set, command listing displays only files in the path
that are executable. Slow.
-
rmstar
(+)
- If set, the user is prompted before
rm *
is executed.
-
rprompt
(+)
- The string to print on the right-hand side of the screen
(after the command input) when the prompt is being displayed on the left.
It recognizes the same formatting characters as
prompt. It will automatically disappear and
reappear as necessary, to ensure that command input isn't obscured, and
will appear only if the prompt, command input, and itself will fit
together on the first line.
If edit isn't set, then
rprompt will be printed after the prompt and
before the command input.
-
savedirs
(+)
- If set, the shell does
dirs -S
before exiting.
If the first word is set to a number, at most that many directory stack
entries are saved.
- savehist
- If set, the shell does
history -S
before exiting.
If the first word is set to a number, at most that many lines are saved.
(The number should be less than or equal to the number
history entries; if it is set to greater than
the number of history settings, only
history entries will be saved.)
If the second word is set to ‘merge
’,
the history list is merged with the existing history file instead of
replacing it (if there is one) and sorted by time stamp and the most
recent events are retained.
If the second word is set to ‘merge
’
and the third word is set to ‘lock
’,
the history file update will be serialized with other shell sessions that
would possibly like to merge history at exactly the same time. (+)
-
sched
(+)
- The format in which the sched
builtin command prints scheduled events; if not given,
‘
%h\t%T\t%R\n
’ is used. The format
sequences are described above under prompt;
note the variable meaning of
‘%R
’.
- shell
- The file in which the shell resides. This is used in
forking shells to interpret files which have execute bits set, but which
are not executable by the system. (See the description of
Builtin
and non-builtin command execution.) Initialized to the
(system-dependent) home of the shell.
-
shlvl
(+)
- The number of nested shells. Reset to 1 in login shells.
See also loginsh.
- status
- The exit status from the last command or backquote
expansion, or any command in a pipeline is propagated to
status. (This is also the default
csh(1) behavior.) This default does not match
what POSIX mandates (to return the status of the last command only). To
match the POSIX behavior, you need to unset
anyerror.
If the anyerror variable is unset, the exit
status of a pipeline is determined only from the last command in the
pipeline, and the exit status of a backquote expansion is
not propagated to
status.
If a command terminated abnormally, then 0200 is added to the status.
Builtin commands which fail return exit status
‘
1
’, all other builtin commands
return status ‘0
’.
-
symlinks
(+)
- Can be set to several different values to control symbolic
link (‘symlink’) resolution:
If set to ‘
chase
’, whenever the
current directory changes to a directory containing a symbolic link, it is
expanded to the real name of the directory to which the link points. This
does not work for the user's home directory; this is a bug.
If set to ‘ignore
’, the shell tries to
construct a current directory relative to the current directory before the
link was crossed. This means that
cd
through a symbolic link and then
cd ..
returns one to the original directory. This affects only builtin commands
and filename completion.
If set to ‘expand
’, the shell tries to
fix symbolic links by actually expanding arguments which look like path
names. This affects any command, not just builtins. Unfortunately, this
does not work for hard-to-recognize filenames, such as those embedded in
command options. Expansion may be prevented by quoting. While this setting
is usually the most convenient, it is sometimes misleading and sometimes
confusing when it fails to recognize an argument which should be expanded.
A compromise is to use ‘ignore
’ and
use the editor command normalize-path (bound
by default to ^X-n) when necessary.
Some examples are in order. First, let's set up some play directories:
Here's the behavior with symlinks unset,
Here's the behavior with symlinks set to
‘chase
’,
Here's the behavior with symlinks set to
‘ignore
’,
Here's the behavior with symlinks set to
‘expand
’.
Note that ‘expand
’ expansion:
- Works just like
‘
ignore
’ for builtins like
cd.
- Is prevented by quoting.
- Happens before filenames are passed to non-builtin
commands.
-
tcsh
(+)
- The version number of the shell in the format
‘R.VV.PP’,
where ‘R’ is the major
release number, ‘VV’ the
current version, and ‘PP’
the patchlevel.
- term
- The terminal type. Usually set in
~/.login as described under
Startup and
shutdown.
- time
- If set to a number, then the
time builtin executes automatically after
each command which takes more than that many CPU seconds.
If there is a second word, it is used as a format string for the output of
the time builtin.
(u) The following sequences may be used in the
time format string:
Only the first four sequences are supported on systems without BSD resource
limit functions. The default time format is ‘
%Uu
%Ss %E %P %X+%Dk %I+%Oio %Fpf+%Ww
’ for systems that support
resource usage reporting and ‘%Uu %Ss %E
%P
’ for systems that do not.
Under Sequent's DYNIX/ptx, ‘%X
’,
‘%D
’,
‘%K
’,
‘%r
’, and
‘%s
’ are not available, but the
following additional sequences are:
and the default time format is ‘%Uu %Ss %E %P
%I+%Oio %Fpf+%Ww
’.
Note that the CPU percentage can be higher than 100% on
multi-processors.
-
tperiod
(+)
- The period, in minutes, between executions of the
periodic special alias.
-
tty
(+)
- The name of the tty, or empty if not attached to one.
-
uid
(+)
- The user's real user ID.
- user
- The user's login name.
- verbose
- If set, causes the words of each command to be printed,
after history substitution (if any). Set by the
-v command line option.
-
version
(+)
- The version ID stamp. It contains the shell's version
number (see tcsh), origin, release date,
vendor, operating system and machine (see
VENDOR
,
OSTYPE
, and
MACHTYPE
) and a comma-separated list of
options which were set at compile time. Options which are set by default
in the distribution are noted.
Supported version options include:
An administrator may enter additional strings to indicate differences in the
local version.
-
vimode
(+)
- If unset, various key bindings change behavior to be more
emacs(1)-style: word boundaries are
determined by wordchars versus other
characters.
If set, various key bindings change behavior to be more
vi(1)-style: word boundaries are determined
by wordchars versus whitespace versus other
characters; cursor behavior depends upon current vi mode (command, delete,
insert, replace).
This variable is unset by bindkey
-e and set by
bindkey -v.
vimode may be explicitly set or unset by the
user after those bindkey operations if
required.
-
visiblebell
(+)
- If set, a screen flash is used rather than the audible
bell. See also nobeep.
-
watch
(+)
- A list of user/terminal pairs to watch for logins and
logouts. If either the user is ‘
any
’
all terminals are watched for the given user and vice versa. Setting
watch to
(any any)
watches all users and terminals. For example,
reports activity of the user ‘george
’
on ‘ttyd1
’, any user on the console,
and oneself (or a trespasser) on any terminal.
Logins and logouts are checked every 10 minutes by default, but the first
word of watch can be set to a number to check
every so many minutes. For example,
reports any login/logout once every minute. For the impatient, the
log builtin command triggers a
watch report at any time. All current logins
are reported (as with the log builtin) when
watch is first set.
The who shell variable controls the format of
watch reports.
-
who
(+)
- The format string for watch
messages. The following sequences are replaced by the given information:
‘
%M
’ and
‘%m
’ are available on only systems
that store the remote hostname in /etc/utmp.
If unset,
%n has %a %l from %m.
is used, or
%n has %a %l.
on systems which don't store the remote hostname.
-
wordchars
(+)
- A list of non-alphanumeric characters to be considered part
of a word by the forward-word,
backward-word, etc., editor commands.
If unset, the default value is determined based on the state of
vimode: if
vimode is unset,
‘
*?_-.[]~=
’ is used as the default;
if vimode is set,
‘_
’ is used as the default.
-
AFSUSER
(+)
- Equivalent to the afsuser
shell variable.
COMMAND_LINE
- Set by tcsh to the current
command line when invoking programs for the
complete
list mode
‘
`...`
’. See
complete in
Builtin
commands.
COLUMNS
- The number of columns in the terminal. See
Terminal
management (+).
DISPLAY
- Used by X Window System (see
X(1)). If set, the shell does not set
autologout.
EDITOR
- The pathname to a default editor. Used by the
run-fg-editor editor command if the the
editors shell variable is unset. See also the
VISUAL
environment variable.
-
GROUP
(+)
- Equivalent to the group shell
variable.
HOME
- Equivalent to the home shell
variable.
-
HOST
(+)
- Initialized to the name of the machine on which the shell
is running, as determined by the
gethostname(2) system call.
-
HOSTTYPE
(+)
- Initialized to the type of machine on which the shell is
running, as determined at compile time. This variable is obsolete and will
be removed in a future version.
-
HPATH
(+)
- A colon-separated list of directories in which the
run-help editor command looks for command
documentation.
LANG
- Gives the preferred character environment. See
Native
Language System support (+).
LC_CTYPE
- If set, only ctype character handling is changed. See
Native
Language System support (+).
LINES
- The number of lines in the terminal. See
Terminal
management (+).
LS_COLORS
- The format of this variable is reminiscent of the
termcap(5) file format; a colon-separated
list of expressions of the form
"
xx=
string"
,
where
"
xx"
is a two-character variable name.
The variables with their associated defaults are:
Var |
Default |
File type
|
no |
0 |
Normal (non-filename) text. |
fi |
0 |
Regular file. |
di |
01;34 |
Directory. |
ln |
01;36 |
Symbolic link. |
pi |
33 |
Named pipe (FIFO). |
so |
01;35 |
Socket. |
do |
01;35 |
Door. |
bd |
01;33 |
Block device. |
cd |
01;32 |
Character device. |
ex |
01;32 |
Executable file. |
mi |
(none) |
Missing file (defaults to
fi ). |
or |
(none) |
Orphaned symbolic link (defaults to
ln ). |
lc |
^[[ |
Left code. |
rc |
m |
Right code. |
ec |
(none) |
End code (replaces
lc +no +rc ). |
You need to include only the variables you want to change from the default.
File names can also be colorized based on filename extension. This is
specified in the LS_COLORS
variable
using the syntax
"*
ext=
string"
.
For example, using ISO 6429 codes, to color all C-language source files
blue you would specify "*.c=34"
. This
would color all files ending in ‘.c
’
in blue (34) color.
Control characters can be written either in C-style-escaped notation, or in
stty-like ^-notation. The C-style notation adds
‘^[
’ for Escape,
‘_
’ for a normal space character,
and ‘?
’ for Delete. In addition, the
‘^[
’ escape character can be used to
override the default interpretation of
‘^[
’,
‘^
’,
‘:
’, and
‘=
’.
Each file will be written as
lc
color-code rc
filename
ec
If the ‘ec
’ code is undefined, the
sequence
lc no rc
will be used instead. This is generally more convenient to use, but less
general.
The left code (‘lc
’), right code
(‘rc
’), and end codes
(‘ec
’) are provided so you don't
have to type common parts over and over again and to support weird
terminals; you will generally not need to change them at all unless your
terminal does not use ISO 6429 color sequences but a different system.
If your terminal does use ISO 6429 color codes, you can compose the type
codes (i.e., all except the ‘lc
’,
‘rc
’, and
‘ec
’ codes) from numerical commands
separated by semicolons.
The most common color commands are:
Not all commands will work on all systems or display devices.
A few terminal programs do not recognize the default end code properly. If
all text gets colorized after you do a directory listing, try changing the
‘no
’ and
‘fi
’ codes from 0 to the numerical
codes for your standard fore- and background colors.
For symbolic links the ‘ln
’ keyword
can be set to ‘target
’, which makes
the file color the same as the color of the link target.
-
MACHTYPE
(+)
- The machine type (microprocessor class or machine model),
as determined at compile time.
-
NOREBIND
(+)
- If set, printable characters are not rebound to
self-insert-command. See
Native
Language System support (+).
-
OSTYPE
(+)
- The operating system, as determined at compile time.
PATH
- A colon-separated list of directories in which to look for
executables. Equivalent to the path shell
variable, but in a different format.
-
PWD
(+)
- Equivalent to the cwd shell
variable, but not synchronized to it; updated only after an actual
directory change.
-
REMOTEHOST
(+)
- The host from which the user has logged in remotely, if
this is the case and the shell is able to determine it. Set only if the
shell was so compiled; see the version shell
variable.
-
SHLVL
(+)
- Equivalent to the shlvl shell
variable.
-
SYSTYPE
(+)
- The current system type. (Domain/OS only)
TERM
- Equivalent to the term shell
variable.
TERMCAP
- The terminal capability string. See
Terminal
management (+).
USER
- Equivalent to the user shell
variable.
-
VENDOR
(+)
- The vendor, as determined at compile time.
VISUAL
- The pathname to a default full-screen editor. Used by the
run-fg-editor editor command if the the
editors shell variable is unset. See also the
EDITOR
environment variable.
- /etc/csh.cshrc
- Read first by every shell.
ConvexOS, Stellix and Intel use /etc/cshrc.
NeXTs use /etc/cshrc.std.
A/UX, AMIX, Cray and IRIX have no equivalent in
csh(1), but read this file in
tcsh anyway.
Solaris 2.x does not have it either, but tcsh
reads /etc/.cshrc.
(+)
- /etc/csh.login
- Read by login shells after
/etc/csh.cshrc.
ConvexOS, Stellix and Intel use /etc/login.
NeXTs use /etc/login.std.
Solaris 2.x uses /etc/.login.
A/UX, AMIX, Cray and IRIX use /etc/cshrc.
-
~/.tcshrc
(+)
- Read by every shell after
/etc/csh.cshrc or its equivalent.
- ~/.cshrc
- Read by every shell, if
~/.tcshrc doesn't exist, after
/etc/csh.cshrc or its equivalent.
This manual uses ‘~/.tcshrc’ to
mean “~/.tcshrc or, if
~/.tcshrc is not found,
~/.cshrc”.
- ~/.history
- Read by login shells after
~/.tcshrc if
savehist is set, but see also
histfile.
- ~/.login
- Read by login shells after
~/.tcshrc or
~/.history.
The shell may be compiled to read ~/.login
before instead of after ~/.tcshrc and
~/.history; see the
version shell variable.
-
~/.cshdirs
(+)
- Read by login shells after
~/.login if
savedirs is set, but see also
dirsfile.
- /etc/csh.logout
- Read by login shells at logout.
ConvexOS, Stellix and Intel use /etc/logout.
NeXTs use /etc/logout.std.
A/UX, AMIX, Cray and IRIX have no equivalent in
csh(1), but read this file in
tcsh anyway.
Solaris 2.x does not have it either, but tcsh
reads /etc/.logout. (+)
- ~/.logout
- Read by login shells at logout after
/etc/csh.logout or its equivalent.
- /bin/sh
- Used to interpret shell scripts not starting with a
‘
#
’.
- /tmp/sh*
- Temporary file for
‘
<<
’.
- /etc/passwd
- Source of home directories for ‘~name’
substitutions.
The order in which startup files are read may differ if the shell was so
compiled; see
Startup
and shutdown and the
version shell variable.
This manual describes
tcsh as a single entity, but
experienced
csh(1) users will want to pay special
attention to
tcsh's new features.
A command-line editor, which supports
emacs(1)-style or
vi(1)-style key bindings. See
The command-line
editor (+) and
Editor
commands (+).
Programmable, interactive word completion and listing. See
Completion and
listing (+) and the
complete and
uncomplete builtin commands.
Spelling correction
(+) of filenames, commands and variables.
Editor commands (+)
which perform other useful functions in the middle of typed commands,
including documentation lookup (
run-help), quick
editor restarting (
run-fg-editor), and command
resolution (
which-command).
An enhanced history mechanism. Events in the history list are time-stamped. See
also the
history command and its associated shell
variables, the previously undocumented
‘
#
’ event specifier and new modifiers
under
History
substitution, the
down-history,
expand-history,
history-search-backward,
history-search-forward,
i-search-back,
i-search-fwd,
toggle-literal-history,
vi-search-back,
vi-search-fwd, and
up-history editor commands and the
histlit shell variable.
Enhanced directory parsing and directory stack handling. See the
cd,
pushd,
popd, and
dirs
commands and their associated shell variables, the description of
Directory
stack substitution (+), the
dirstack,
owd, and
symlinks
shell variables and the
normalize-command and
normalize-path editor commands.
Negation in glob-patterns. See
Filename
substitution.
New
File inquiry
operators and a
filetest builtin which uses
them.
A variety of
Automatic,
periodic and timed events (+) including scheduled events, special aliases,
automatic logout and terminal locking, command timing and watching for logins
and logouts.
Support for the Native Language System (see
Native
Language System support (+)), OS variant features (see
OS variant support
(+) and the
echo_style shell variable) and
system-dependent file locations (see
FILES).
Extensive terminal-management capabilities. See
Terminal management
(+).
New builtin commands including
builtins,
hup,
ls-F,
newgrp,
printenv,
which, and
where.
New variables that make useful information easily available to the shell. See
the
gid,
loginsh,
oid,
shlvl,
tcsh,
tty,
uid, and
version
shell variables and the
HOST
,
REMOTEHOST
,
VENDOR
,
OSTYPE
, and
MACHTYPE
environment variables.
A new syntax for including useful information in the prompt string (see
prompt), and special prompts for loops and
spelling correction (see
prompt2 and
prompt3).
Read-only variables. See
Variable
substitution.
In 1964, DEC produced the PDP-6. The PDP-10 was a later re-implementation. It
was re-christened the DECsystem-10 in 1970 or so when DEC brought out the
second model, the KI10.
TENEX was created at Bolt, Beranek & Newman (a Cambridge, Massachusetts
think tank) in 1972 as an experiment in demand-paged virtual memory operating
systems. They built a new pager for the DEC PDP-10 and created the OS to go
with it. It was extremely successful in academia.
In 1975, DEC brought out a new model of the PDP-10, the KL10; they intended to
have only a version of TENEX, which they had licensed from BBN, for the new
box. They called their version TOPS-20 (their capitalization is trademarked).
A lot of TOPS-10 users (`The OPerating System for PDP-10') objected; thus DEC
found themselves supporting two incompatible systems on the same hardware--but
then there were 6 on the PDP-11!
TENEX, and TOPS-20 to version 3, had command completion via a user-code-level
subroutine library called ULTCMD. With version 3, DEC moved all that
capability and more into the monitor (`kernel' for you Unix types), accessed
by the COMND% JSYS (`Jump to SYStem' instruction, the supervisor call
mechanism [are my IBM roots also showing?]).
The creator of tcsh was impressed by this feature and several others of TENEX
and TOPS-20, and created a version of csh which mimicked them.
The system limits argument lists to ARG_MAX characters.
The number of arguments to a command which involves filename expansion is
limited to 1/6th the number of characters allowed in an argument list.
Command substitutions may substitute no more characters than are allowed in an
argument list.
To detect looping, the shell restricts the number of
alias substitutions on a single line to 20.
csh(1),
emacs(1),
ls(1),
newgrp(1),
setpath(1),
sh(1),
stty(1),
su(1),
tset(1),
vi(1),
x(1),
access(2),
execve(2),
fork(2),
killpg(2),
pipe(2),
setrlimit(2),
sigvec(2),
stat(2),
umask(2),
vfork(2),
wait(2),
malloc(3),
setlocale(3),
tty(4),
a.out(5),
termcap(5),
environ(7),
termio(7),
Introduction
to the C Shell
This manual documents tcsh 6.24.07 (Astron) 2022-12-21.
-
William Joy.
-
Original author of csh(1).
-
J.E. Kulp,
- IIASA, Laxenburg, Austria.
Job control and directory stack features.
-
Ken Greer,
- HP Labs, 1981.
File name completion.
-
Mike Ellis,
- Fairchild, 1983.
Command name recognition/completion.
-
Paul Placeway,
- Ohio State CIS Dept.,
1983-1993.
Command line editor, prompt routines, new glob syntax and numerous fixes and
speedups.
-
Karl Kleinpaste,
- CCI, 1983-4.
Special aliases, directory stack extraction stuff, login/logout watch,
scheduled events, and the idea of the new prompt format.
-
Rayan
Zachariassen,
- University of Toronto, 1984.
ls-F and which
builtins and numerous bug fixes, modifications and speedups.
-
Chris Kingsley,
- Caltech.
Fast storage allocator routines.
-
Chris Grevstad,
- TRW, 1987.
Incorporated 4.3BSD csh(1) into
tcsh.
-
Christos S.
Zoulas,
- Cornell U. EE Dept., 1987-94.
Ports to HPUX, SVR2 and SVR3, a SysV version of getwd.c, SHORT_STRINGS
support and a new version of sh.glob.c.
-
James J Dempsey,
- BBN, and
Paul Placeway, OSU, 1988.
A/UX port.
-
Daniel Long,
- NNSC, 1988.
wordchars.
-
Patrick Wolfe,
- Kuck and Associates, Inc.,
1988.
vi mode cleanup.
-
David C Lawrence,
- Rensselaer Polytechnic
Institute, 1989.
autolist and ambiguous completion listing.
-
Alec Wolman,
- DEC, 1989.
Newlines in the prompt.
-
Matt Landau,
- BBN, 1989.
~/.tcshrc.
-
Ray Moody,
- Purdue Physics, 1989.
Magic space bar history expansion.
-
Mordechai ????,
- Intel, 1989.
printprompt() fixes and additions.
-
Kazuhiro Honda,
- Dept. of Computer Science,
Keio University, 1989.
Automatic spelling correction and prompt3.
-
Per Hedeland,
- Ellemtel, Sweden, 1990-.
Various bugfixes, improvements and manual updates.
-
Hans J.
Albertsson,
- Sun Sweden.
ampm, settc, and
telltc.
-
Michael Bloom.
-
Interrupt handling fixes.
-
Michael Fine,
- Digital Equipment Corp.
Extended key support.
-
Eric Schnoebelen,
- Convex, 1990.
Convex support, lots of csh(1) bug fixes, save
and restore of directory stack.
-
Ron Flax,
- Apple, 1990.
A/UX 2.0 (re)port.
-
Dan Oscarsson,
- LTH Sweden, 1990.
NLS support and simulated NLS support for non NLS sites, fixes.
-
Johan Widen,
- SICS Sweden, 1990.
shlvl, Mach support,
correct-line, 8-bit printing.
-
Matt Day,
- Sanyo Icon, 1990.
POSIX termio support, SysV limit fixes.
-
Jaap Vermeulen,
- Sequent, 1990-91.
Vi mode fixes, expand-line, window change fixes, Symmetry port.
-
Martin Boyer,
- Institut de recherche
d'Hydro-Quebec, 1991.
autolist beeping options, modified the history
search to search for the whole string from the beginning of the line to
the cursor.
-
Scott Krotz,
- Motorola, 1991.
Minix port.
-
David Dawes,
- Sydney U. Australia, Physics
Dept., 1991.
SVR4 job control fixes.
-
Kimmo Suominen,
- 1991-.
Various portability and other fixes. Added
‘$''
’ (dollar-single-quotes).
-
Jose Sousa,
- Interactive Systems Corp.,
1991.
Extended vi fixes and
vi delete command.
-
Marc Horowitz,
- MIT, 1991.
ANSIfication fixes, new exec hashing code, imake fixes,
where.
-
Luke Mewburn,
- 1991-.
Enhanced directory printing in prompt. Added
ellipsis and
rprompt. vimode
improvements. Manual page improvements.
-
Bruce Sterling
Woodcock,
- [email protected],
1991-1995.
ETA and Pyramid port, Makefile and lint fixes,
ignoreeof=n
addition, and various other portability changes and bug fixes.
-
Jeff Fink,
- 1992.
complete-word-fwd and
complete-word-back.
-
Harry C. Pulley,
- 1992.
Coherent port.
-
Andy Phillips,
- Mullard Space Science Lab
U.K., 1992.
VMS-POSIX port.
-
Beto Appleton,
- IBM Corp., 1992.
Walking process group fixes, csh(1) bug fixes,
POSIX file tests, POSIX SIGHUP.
-
Scott Bolte,
- Cray Computer Corp., 1992.
CSOS port.
-
Kaveh R. Ghazi,
- Rutgers University, 1992.
Tek, m88k, Titan and Masscomp ports and fixes. Added autoconf support.
-
Mark Linderman,
- Cornell University, 1992.
OS/2 port.
-
Mika Liljeberg,
- [email protected],
1992.
Linux port.
-
Tim P. Starrin,
- NASA Langley Research Center
Operations, 1993.
Read-only variables.
-
Dave Schweisguth,
- Yale University, 1993-4.
New man page and tcsh.man2html.
-
Larry Schwimmer,
- Stanford University, 1993.
AFS and HESIOD patches.
-
Edward Hutchins,
- Silicon Graphics Inc., 1996.
Added implicit cd.
-
Martin Kraemer,
- 1997.
Ported to Siemens Nixdorf EBCDIC machine.
-
Amol Deshpande,
- Microsoft, 1997.
Ported to WIN32 (Windows/95 and Windows/NT); wrote all the missing library
and message catalog code to interface to Windows.
-
Taga Nayuta,
- 1998.
Color ls additions.
Bryan Dunlap, Clayton Elwell, Karl Kleinpaste, Bob Manson, Steve Romig, Diana
Smetters, Bob Sutterfield, Mark Verber, Elizabeth Zwicky and all the other
people at Ohio State for suggestions and encouragement
All the people on the net, for putting up with, reporting bugs in, and
suggesting new additions to each and every version
Richard M. Alderson III, for writing the
T in tcsh section
When a suspended command is restarted, the shell prints the directory it started
in if this is different from the current directory. This can be misleading
(i.e., wrong) as the job may have changed directories internally.
Shell builtin functions are not stoppable/restartable. Command sequences of the
form
a ; b ; c
are also not handled gracefully when stopping is attempted. If you suspend
‘
b
’, the shell will then immediately
execute ‘
c
’. This is especially
noticeable if this expansion results from an
alias. It suffices to place the sequence of
commands in ‘
()
’'s to force it to a
subshell, i.e.,
( a ; b ; c )
Control over tty output after processes are started is primitive; perhaps this
will inspire someone to work on a good virtual terminal interface. In a
virtual terminal interface much more interesting things could be done with
output control.
Alias substitution is most often used to clumsily simulate shell procedures;
shell procedures should be provided rather than aliases.
Control structures should be parsed rather than being recognized as built-in
commands. This would allow control commands to be placed anywhere, to be
combined with ‘
|
’, and to be used with
‘
&
’ and
‘
;
’ metasyntax.
foreach doesn't ignore here documents when looking
for its
end.
It should be possible to use the ‘
:
’
modifiers on the output of command substitutions.
The screen update for lines longer than the screen width is very poor if the
terminal cannot move the cursor up (i.e., terminal type
‘
dumb
’).
HPATH
and
NOREBIND
don't need to be environment
variables.
Glob-patterns which do not use ‘
?
’,
‘
*
’, or
‘
[]
’, or which use
‘
{}
’ or
‘
~
’ are not negated correctly.
The single-command form of
if does output
redirection even if the expression is false and the command is not executed.
ls-F includes file identification characters when
sorting filenames and does not handle control characters in filenames well. It
cannot be interrupted.
Command substitution supports multiple commands and conditions, but not cycles
or backward
gotos.
Report bugs at
https://bugs.astron.com/
preferably with fixes. If you want to help maintain and test tcsh, add
yourself to the mailing list in
https://mailman.astron.com/mailman/listinfo/tcsh