pmcpp - simple preprocessor for the Performance Co-Pilot
pmcpp [
-Prs?] [
-D name[=
value] ...] [
-I dir ...] [[
infile] [
outfile]]
pmcpp provides a very simple pre-processor originally designed for
manipulating Performance Metric Name Space (PMNS) files for the Performance
Co-Pilot (PCP), but later generalized to provide conditional blocks, include
file processing, in-line shell command execution and macro substitution for
arbitrary files. It is most commonly used internally to process the PMNS
file(s) after
pmLoadNameSpace(3) or
pmLoadASCIINameSpace(3) is
called and to pre-process the configuration files for
pmlogger(1).
Input lines are read from
infile (or standard input if
infile is
not specified), processed and written to
outfile (standard output if
outfile is not specified).
All C-style comments of the form /* ... */ are stripped from the input stream.
There are no predefined macros for
pmcpp although macros may be defined
on the command line using the
-D option, where
name and
value must follow the same rules as described below for the
#define directive.
pmcpp accepts the following directives in the input stream (like
cpp(1)):
- •
-
#include "filename"
or
#include <filename>
In either case the directory search path for filename tries
filename first, then the directory for the command line
infile (if any), followed by any directories named in -I
command line arguments, and finally the $PCP_VAR_DIR/pmns directory
(the latter is for backwards compatibility with earlier versions of
pmcpp and the implied used from pmLoadASCIINameSpace(3)).
#include directives may be nested, up to a maximum depth of 5.
- •
-
#shell "command"
or
#shell 'command'
The shell command will be executed and the standard output is
inserted into the stream of data to be processed by pmcpp.
Functionally this is similar to a #include directive, except input
lines are read from a command rather than a file. The #shell
directive is most useful for including or excluding #define or
#undef directives based on run-time logic in the
command.
- •
-
#define name value
or
#define name "value"
or
#define name 'value'
Defines a value for the macro name which must be a valid C-style
name, so leading alphabetic or underscore followed by zero or more
alphanumerics or underscores. value is optional (and defaults to an
empty string). There is no character escape mechanism, but either single
quotes or double quotes may be used to define a value with special
characters or embedded horizontal white space (no newlines).
- •
-
#undef name
Removes the macro definition, if any, for name.
- •
-
#ifdef name
...
#endif
or
#ifndef name
...
#endif
The enclosing lines will be stripped or included, depending if the macro
name is defined or not.
- •
-
#else
Within a #ifdef or #ifndef block, #else may be used to
delimit lines to be included if the preceding ``if'' condition is
false.
Macro substitution is achieved by breaking the input stream into words separated
by white space or characters that are not valid in a macro name, i.e. not
alphanumeric and not underscore. Each word is checked and if it matches a
macro name, the word is replaced by the macro value, otherwise the word is
unchanged.
There is generally one output line for each input line, although the line may be
empty if the text has been stripped due to the handling of comments or
conditional directives. When there is a change in the input stream, an
additional output line is generated of the form:
# lineno "filename"
to indicate the
following line of output corresponds to line number
lineno of the input file
filename.
The available command line options are:
-
-D name[=value],
--define=name[=value]
- Defines a macro with an optional value, as described
earlier.
-
-I dir, --include=dir
- An additional directory to search for include files.
- -P
- Suppresses the generation of the linemarker lines,
described above.
-
-s, --shell
- Changes the expected input style from C-like to shell-like
(where # is a comment prefix). This forces the following changes in
pmcpp behaviour:
- •
- The control prefix character changes from # to
%, so %include for example.
- •
- No comment stripping is performed.
-
-r, --restrict
- Provide finer control of macro expansion - this option
restricts macro substitution to words that match the patterns #name
or #{name} or if -s is specified, then %name
or %{name}. In this mode, the macro name alone in the
input stream will never be expanded, however in control lines (like
#ifdef) the macro name should appear alone with out the
prefix character or the curly braces (refer to the EXAMPLES below).
Important
cpp(1) features that are
not supported by
pmcpp
include:
- •
- Macros with parameters - the pmcpp macros support
only parameterless string substitution.
- •
-
#if expr
...
#endif
- •
- Nested use of #ifdef or #ifndef.
- •
- Stripping C++ style comments, as in // comment.
- •
- Error recovery - the first error encountered by
pmcpp will be fatal.
- •
-
cpp(1) command line options like -o,
-W, -U, and -x.
-
-?, --help
- Display usage message and exit.
Command: pmcpp
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Input |
Output |
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# 1 "<stdin>" |
|
#define MYDOMAIN 27 |
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root { |
root { |
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foo MYDOMAIN:0:0 |
foo 27:0:0 |
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} |
} |
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For the following examples, the file
frequencies contains the lines:
%define dk_freq 1minute
%define cpu_freq '15 sec'
Command: pmcpp -rs
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Input |
Output |
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# get logging frequencies |
# get logging frequencies |
|
# e.g. dk_freq macro |
# e.g. dk_freq macro |
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%include "frequencies" |
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log mandatory on %dk_freq { |
log mandatory on 1minute { |
|
disk.dev |
disk.dev |
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} |
} |
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# note no % for want_cpu here |
# note no % for want_cpu here |
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%ifdef want_cpu |
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%define cpu_pfx 'kernel.all.cpu.' |
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log mandatory on %cpu_freq { |
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%{cpu_pfx}user |
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%{cpu_pfx}sys |
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} |
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%endif |
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Command: pmcpp -rs -Dwant_cpu
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Input |
Output |
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# get logging frequencies |
# get logging frequencies |
|
# e.g. dk_freq macro |
# e.g. dk_freq macro |
|
%include "frequencies" |
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log mandatory on %dk_freq { |
log mandatory on 1minute { |
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disk.dev |
disk.dev |
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} |
} |
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# note no % for want_cpu here |
# note no % for want_cpu here |
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%ifdef want_cpu |
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%define cpu_pfx 'kernel.all.cpu.' |
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log mandatory on %cpu_freq { |
log mandatory on 15 sec { |
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%{cpu_pfx}user |
kernel.all.cpu.user |
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%{cpu_pfx}sys |
kernel.all.cpu.sys |
|
} |
} |
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%endif |
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Environment variables with the prefix
PCP_ are used to parameterize the
file and directory names used by PCP. On each installation, the file
/etc/pcp.conf contains the local values for these variables. The
$PCP_CONF variable may be used to specify an alternative configuration
file, as described in
pcp.conf(5).
For environment variables affecting PCP tools, see
pmGetOptions(3).
cpp(1),
pmLoadASCIINameSpace(3),
pmLoadNameSpace(3),
pcp.conf(5),
pcp.env(5) and
PMNS(5).