sudo,
sudoedit
—
execute a command as another user
sudo |
-v
[-ABkNnS]
[-g
group]
[-h
host]
[-p
prompt]
[-u
user] |
sudo |
-l
[-ABkNnS]
[-g
group]
[-h
host]
[-p
prompt]
[-U
user]
[-u
user]
[command
[arg
...]] |
sudo |
[-ABbEHnPS]
[-C
num]
[-D
directory]
[-g
group]
[-h
host]
[-p
prompt]
[-R
directory]
[-r
role]
[-t
type]
[-T
timeout]
[-u
user]
[VAR=value]
[-i |
-s]
[command
[arg
...]] |
sudoedit |
[-ABkNnS]
[-C
num]
[-D
directory]
[-g
group]
[-h
host]
[-p
prompt]
[-R
directory]
[-r
role]
[-t
type]
[-T
timeout]
[-u
user]
file ...
|
sudo allows a permitted user to execute a
command as the superuser or another user, as
specified by the security policy. The invoking user's real
(
not effective) user-ID
is used to determine the user name with which to query the security policy.
sudo supports a plugin architecture for security
policies, auditing, and input/output logging. Third parties can develop and
distribute their own plugins to work seamlessly with the
sudo front-end. The default security policy is
sudoers, which is configured via the file
/etc/sudoers, or via LDAP. See the
Plugins section for more
information.
The security policy determines what privileges, if any, a user has to run
sudo. The policy may require that users
authenticate themselves with a password or another authentication mechanism.
If authentication is required,
sudo will exit if
the user's password is not entered within a configurable time limit. This
limit is policy-specific; the default password prompt timeout for the
sudoers security policy is 0 minutes.
Security policies may support credential caching to allow the user to run
sudo again for a period of time without requiring
authentication. By default, the
sudoers policy
caches credentials on a per-terminal basis for 15 minutes. See the
timestamp_type and
timestamp_timeout options in
sudoers(5) for more information. By running
sudo with the
-v
option, a user can update the cached credentials without running a
command.
On systems where
sudo is the primary method of
gaining superuser privileges, it is imperative to avoid syntax errors in the
security policy configuration files. For the default security policy,
sudoers(5), changes to the configuration files
should be made using the
visudo(8) utility which
will ensure that no syntax errors are introduced.
When invoked as
sudoedit, the
-e option (described below), is implied.
Security policies and audit plugins may log successful and failed attempts to
run
sudo. If an I/O plugin is configured, the
running
command's input and output may be
logged as well.
The options are as follows:
-
-A,
--askpass
- Normally, if sudo requires a
password, it will read it from the user's terminal. If the
-A (askpass)
option is specified, a (possibly graphical) helper program is executed to
read the user's password and output the password to the standard output.
If the
SUDO_ASKPASS
environment
variable is set, it specifies the path to the helper program. Otherwise,
if sudo.conf(5) contains a line specifying
the askpass program, that value will be used. For example:
If no askpass program is available, sudo will
exit with an error.
-
-B,
--bell
- Ring the bell as part of the password prompt when a
terminal is present. This option has no effect if an askpass program is
used.
-
-b,
--background
- Run the given command in
the background. It is not possible to use shell job control to manipulate
background processes started by sudo. Most
interactive commands will fail to work
properly in background mode.
-
-C
num,
--close-from=num
- Close all file descriptors greater than or equal to
num before executing a
command. Values less than three are not
permitted. By default, sudo will close all
open file descriptors other than standard input, standard output, and
standard error when executing a command.
The security policy may restrict the user's ability to use this option.
The sudoers policy only permits use of the
-C option when the administrator has enabled
the closefrom_override option.
-
-D
directory,
--chdir=directory
- Run the command in the
specified directory instead of the
current working directory. The security policy may return an error if the
user does not have permission to specify the working directory.
-
-E,
--preserve-env
- Indicates to the security policy that the user wishes to
preserve their existing environment variables. The security policy may
return an error if the user does not have permission to preserve the
environment.
- --preserve-env=list
- Indicates to the security policy that the user wishes to
add the comma-separated list of environment variables to those preserved
from the user's environment. The security policy may return an error if
the user does not have permission to preserve the environment. This option
may be specified multiple times.
-
-e,
--edit
- Edit one or more files
instead of running a command. In lieu of
a path name, the string "sudoedit" is used when consulting the
security policy. If the user is authorized by the policy, the following
steps are taken:
- Temporary copies are made of the files to be edited
with the owner set to the invoking user.
- The editor specified by the policy is run to edit the
temporary files. The sudoers policy uses
the
SUDO_EDITOR
,
VISUAL
and
EDITOR
environment variables (in
that order). If none of
SUDO_EDITOR
,
VISUAL
or
EDITOR
are set, the first program
listed in the editor
sudoers(5) option is used.
- If they have been modified, the temporary files are
copied back to their original location and the temporary versions are
removed.
To help prevent the editing of unauthorized files, the following
restrictions are enforced unless explicitly allowed by the security
policy:
- Symbolic links may not be edited (version 1.8.15 and
higher).
- Symbolic links along the path to be edited are not
followed when the parent directory is writable by the invoking user
unless that user is root (version 1.8.16 and higher).
- Files located in a directory that is writable by the
invoking user may not be edited unless that user is root (version
1.8.16 and higher).
Users are never allowed to edit device special files.
If the specified file does not exist, it will be created. Unlike most
commands run by
sudo, the editor is run with the invoking
user's environment unmodified. If the temporary file becomes empty after
editing, the user will be prompted before it is installed. If, for some
reason, sudo is unable to update a file with
its edited version, the user will receive a warning and the edited copy
will remain in a temporary file.
-
-g
group,
--group=group
- Run the command with the
primary group set to group instead of the
primary group specified by the target user's password database entry. The
group may be either a group name or a
numeric group-ID (GID) prefixed with the
‘
#
’ character (e.g.,
‘#0
’ for GID 0). When running a
command as a GID, many shells require
that the ‘#
’ be escaped with a
backslash (‘\
’). If no
-u option is specified, the
command will be run as the invoking user.
In either case, the primary group will be set to
group. The
sudoers policy permits any of the target
user's groups to be specified via the -g
option as long as the -P option is not in
use.
-
-H,
--set-home
- Request that the security policy set the
HOME
environment variable to the home
directory specified by the target user's password database entry.
Depending on the policy, this may be the default behavior.
-
-h,
--help
- Display a short help message to the standard output and
exit.
-
-h
host,
--host=host
- Run the command on the
specified host if the security policy
plugin supports remote commands. The
sudoers plugin does not currently support
running remote commands. This may also be
used in conjunction with the -l option to
list a user's privileges for the remote host.
-
-i,
--login
- Run the shell specified by the target user's password
database entry as a login shell. This means that login-specific resource
files such as .profile,
.bash_profile, or
.login will be read by the shell. If a
command is specified, it is passed to the
shell as a simple command using the
-c option. The
command and any
args are concatenated, separated by
spaces, after escaping each character (including white space) with a
backslash (‘
\
’) except for
alphanumerics, underscores, hyphens, and dollar signs. If no
command is specified, an interactive
shell is executed. sudo attempts to change to
that user's home directory before running the shell. The
command is run with an environment
similar to the one a user would receive at log in. Most shells behave
differently when a command is specified
as compared to an interactive session; consult the shell's manual for
details. The Command environment section in
the sudoers(5) manual documents how the
-i option affects the environment in which a
command is run when the
sudoers policy is in use.
-
-K,
--remove-timestamp
- Similar to the -k option,
except that it removes every cached credential for the user, regardless of
the terminal or parent process ID. The next time
sudo is run, a password must be entered if
the security policy requires authentication. It is not possible to use the
-K option in conjunction with a
command or other option. This option does
not require a password. Not all security policies support credential
caching.
-
-k,
--reset-timestamp
- When used without a
command, invalidates the user's cached
credentials for the current session. The next time
sudo is run in the session, a password must
be entered if the security policy requires authentication. By default, the
sudoers policy uses a separate record in the
credential cache for each terminal (or parent process ID if no terminal is
present). This prevents the -k option from
interfering with sudo commands run in a
different terminal session. See the
timestamp_type option in
sudoers(5) for more information. This option
does not require a password, and was added to allow a user to revoke
sudo permissions from a
.logout file.
When used in conjunction with a command or
an option that may require a password, this option will cause
sudo to ignore the user's cached credentials.
As a result, sudo will prompt for a password
(if one is required by the security policy) and will not update the user's
cached credentials.
Not all security policies support credential caching.
-
-l,
--list
- If no command is
specified, list the privileges for the invoking user (or the
user specified by the
-U option) on the current host. A longer list
format is used if this option is specified multiple times and the security
policy supports a verbose output format.
If a command is specified and is permitted
by the security policy, the fully-qualified path to the
command is displayed along with any
args. If a
command is specified but not allowed by
the policy, sudo will exit with a status
value of 1.
-
-N,
--no-update
- Do not update the user's cached credentials, even if the
user successfully authenticates. Unlike the
-k flag, existing cached credentials are used
if they are valid. To detect when the user's cached credentials are valid
(or when no authentication is required), the following can be used:
sudo -Nnv
Not all security policies support credential caching.
-
-n,
--non-interactive
- Avoid prompting the user for input of any kind. If a
password is required for the command to
run, sudo will display an error message and
exit.
-
-P,
--preserve-groups
- Preserve the invoking user's group vector unaltered. By
default, the sudoers policy will initialize
the group vector to the list of groups the target user is a member of. The
real and effective group-IDs, however, are still set to match the target
user.
-
-p
prompt,
--prompt=prompt
- Use a custom password prompt with optional escape
sequences. The following percent
(‘
%
’) escape sequences are supported
by the sudoers policy:
- %H
- expanded to the host name including the domain name
(only if the machine's host name is fully qualified or the
fqdn option is set in
sudoers(5))
- %h
- expanded to the local host name without the domain
name
- %p
- expanded to the name of the user whose password is
being requested (respects the rootpw,
targetpw, and
runaspw flags in
sudoers(5))
- %U
- expanded to the login name of the user the
command will be run as (defaults to
root unless the -u option is also
specified)
- %u
- expanded to the invoking user's login name
- %%
- two consecutive
‘
%
’ characters are collapsed
into a single ‘%
’ character
The custom prompt will override the default prompt specified by either the
security policy or the SUDO_PROMPT
environment variable. On systems that use PAM, the custom prompt will also
override the prompt specified by a PAM module unless the
passprompt_override flag is disabled in
sudoers.
-
-R
directory,
--chroot=directory
- Change to the specified root
directory (see
chroot(8)) before running the
command. The security policy may return
an error if the user does not have permission to specify the root
directory.
-
-r
role,
--role=role
- Run the command with an
SELinux security context that includes the specified
role.
-
-S,
--stdin
- Write the prompt to the standard error and read the
password from the standard input instead of using the terminal
device.
-
-s,
--shell
- Run the shell specified by the
SHELL
environment variable if it is set
or the shell specified by the invoking user's password database entry. If
a command is specified, it is passed to
the shell as a simple command using the -c
option. The command and any
args are concatenated, separated by
spaces, after escaping each character (including white space) with a
backslash (‘\
’) except for
alphanumerics, underscores, hyphens, and dollar signs. If no
command is specified, an interactive
shell is executed. Most shells behave differently when a
command is specified as compared to an
interactive session; consult the shell's manual for details.
-
-t
type,
--type=type
- Run the command with an
SELinux security context that includes the specified
type. If no
type is specified, the default type is
derived from the role.
-
-U
user,
--other-user=user
- Used in conjunction with the
-l option to list the privileges for
user instead of for the invoking user.
The security policy may restrict listing other users' privileges. When
using the sudoers policy, the
-U option is restricted to the root user and
users with either the “list” priviege for the specified
user or the ability to run any
command as root or
user on the current host.
-
-T
timeout,
--command-timeout=timeout
- Used to set a timeout for the
command. If the timeout expires before
the command has exited, the
command will be terminated. The security
policy may restrict the user's ability to set timeouts. The
sudoers policy requires that user-specified
timeouts be explicitly enabled.
-
-u
user,
--user=user
- Run the command as a user
other than the default target user (usually
root). The
user may be either a user name or a
numeric user-ID (UID) prefixed with the
‘
#
’ character (e.g.,
‘#0
’ for UID 0). When running
commands as a UID, many shells require
that the ‘#
’ be escaped with a
backslash (‘\
’). Some security
policies may restrict UIDs to those listed in the password database. The
sudoers policy allows UIDs that are not in
the password database as long as the targetpw
option is not set. Other security policies may not support this.
-
-V,
--version
- Print the sudo version string
as well as the version string of any configured plugins. If the invoking
user is already root, the -V option will
display the options passed to configure when
sudo was built; plugins may display
additional information such as default options.
-
-v,
--validate
- Update the user's cached credentials, authenticating the
user if necessary. For the sudoers plugin,
this extends the sudo timeout for another 15
minutes by default, but does not run a
command. Not all security policies
support cached credentials.
- --
- The -- is used to delimit the
end of the sudo options. Subsequent options
are passed to the command.
Options that take a value may only be specified once unless otherwise indicated
in the description. This is to help guard against problems caused by poorly
written scripts that invoke
sudo with
user-controlled input.
Environment variables to be set for the
command
may also be passed as options to
sudo in the form
VAR=
value,
for example
LD_LIBRARY_PATH
=
/usr/local/pkg/lib.
Environment variables may be subject to restrictions imposed by the security
policy plugin. The
sudoers policy subjects
environment variables passed as options to the same restrictions as existing
environment variables with one important difference. If the
setenv option is set in
sudoers, the
command to be run has the
SETENV
tag set or the
command matched is
ALL, the user may set variables that would
otherwise be forbidden. See
sudoers(5) for more
information.
When
sudo executes a
command, the security policy specifies the
execution environment for the
command.
Typically, the real and effective user and group and IDs are set to match
those of the target user, as specified in the password database, and the group
vector is initialized based on the group database (unless the
-P option was specified).
The following parameters may be specified by security policy:
- real and effective user-ID
- real and effective group-ID
- supplementary group-IDs
- the environment list
- current working directory
- file creation mode mask (umask)
- SELinux role and type
- scheduling priority (aka nice value)
There are two distinct ways
sudo can run a
command.
If an I/O logging plugin is configured to log terminal I/O, or if the security
policy explicitly requests it, a new pseudo-terminal (“pty”) is
allocated and
fork(2) is used to create a second
sudo process, referred to as the
monitor. The
monitor
creates a new terminal session with itself as the leader and the pty as its
controlling terminal, calls
fork(2) again, sets
up the execution environment as described above, and then uses the
execve(2) system call to run the
command in the child process. The
monitor exists to relay job control signals
between the user's terminal and the pty the
command is being run in. This makes it
possible to suspend and resume the
command
normally. Without the
monitor, the
command would be in what POSIX terms an
“orphaned process group” and it would not receive any job
control signals from the kernel. When the
command exits or is terminated by a signal,
the
monitor passes the
command's exit status to the main
sudo process and exits. After receiving the
command's exit status, the main
sudo process passes the
command's exit status to the security
policy's close function, as well as the close function of any configured audit
plugin, and exits.
If no pty is used,
sudo calls
fork(2), sets up the execution environment as
described above, and uses the
execve(2) system
call to run the
command in the child process.
The main
sudo process waits until the
command has completed, then passes the
command's exit status to the security
policy's close function, as well as the close function of any configured audit
plugins, and exits. As a special case, if the policy plugin does not define a
close function,
sudo will execute the
command directly instead of calling
fork(2) first. The
sudoers policy plugin will only define a close
function when I/O logging is enabled, a pty is required, an SELinux role is
specified, the
command has an associated
timeout, or the
pam_session or
pam_setcred options are enabled. Both
pam_session and
pam_setcred are enabled by default on systems
using PAM.
On systems that use PAM, the security policy's close function is responsible for
closing the PAM session. It may also log the
command's exit status.
When the
command is run as a child of the
sudo process,
sudo
will relay signals it receives to the
command. The
SIGINT
and
SIGQUIT
signals are only relayed when the
command is being run in a new pty or when the
signal was sent by a user process, not the kernel. This prevents the
command from receiving
SIGINT
twice each time the user enters
control-C. Some signals, such as
SIGSTOP
and
SIGKILL
, cannot be caught and thus will
not be relayed to the
command. As a general
rule,
SIGTSTP
should be used instead of
SIGSTOP
when you wish to suspend a
command being run by
sudo.
As a special case,
sudo will not relay signals that
were sent by the
command it is running. This
prevents the
command from accidentally
killing itself. On some systems, the
reboot(8)
utility sends
SIGTERM
to all non-system
processes other than itself before rebooting the system. This prevents
sudo from relaying the
SIGTERM
signal it received back to
reboot(8), which might then exit before the
system was actually rebooted, leaving it in a half-dead state similar to
single user mode. Note, however, that this check only applies to the
command run by
sudo and not any other processes that the
command may create. As a result, running a
script that calls
reboot(8) or
shutdown(8) via
sudo
may cause the system to end up in this undefined state unless the
reboot(8) or
shutdown(8) are run using the
exec() family of functions instead of
system() (which interposes a shell between the
command and the calling process).
Plugins may be specified via
Plugin directives in
the
sudo.conf(5) file. They may be loaded as
dynamic shared objects (on systems that support them), or compiled directly
into the
sudo binary. If no
sudo.conf(5) file is present, or if it doesn't
contain any
Plugin lines,
sudo will use
sudoers(5) for the policy, auditing, and I/O
logging plugins. See the
sudo.conf(5) manual for
details of the
/etc/sudo.conf file and the
sudo_plugin(5) manual for more information about
the
sudo plugin architecture.
Upon successful execution of a
command, the
exit status from
sudo will be the exit status of
the program that was executed. If the
command
terminated due to receipt of a signal,
sudo will
send itself the same signal that terminated the
command.
If the
-l option was specified without a
command,
sudo
will exit with a value of 0 if the user is allowed to run
sudo and they authenticated successfully (as
required by the security policy). If a
command is specified with the
-l option, the exit value will only be 0 if the
command is permitted by the security policy,
otherwise it will be 1.
If there is an authentication failure, a configuration/permission problem, or if
the given
command cannot be executed,
sudo exits with a value of 1. In the latter case,
the error string is printed to the standard error. If
sudo cannot
stat(2)
one or more entries in the user's
PATH
, an
error is printed to the standard error. (If the directory does not exist or if
it is not really a directory, the entry is ignored and no error is printed.)
This should not happen under normal circumstances. The most common reason for
stat(2) to return “permission
denied” is if you are running an automounter and one of the directories
in your
PATH
is on a machine that is
currently unreachable.
sudo tries to be safe when executing external
commands.
To prevent command spoofing,
sudo checks
"." and "" (both denoting current directory) last when
searching for a
command in the user's
PATH
(if one or both are in the
PATH
). Depending on the security policy,
the user's
PATH
environment variable may be
modified, replaced, or passed unchanged to the program that
sudo executes.
Users should
never be granted
sudo privileges to execute files that are
writable by the user or that reside in a directory that is writable by the
user. If the user can modify or replace the
command there is no way to limit what
additional
commands they can run.
By default,
sudo will only log the
command it explicitly runs. If a user runs a
command such as ‘
sudo
su
’ or ‘
sudo sh
’,
subsequent
commands run from that shell are
not subject to
sudo's security policy. The same
is true for
commands that offer shell escapes
(including most editors). If I/O logging is enabled, subsequent
commands will have their input and/or output
logged, but there will not be traditional logs for those
commands. Because of this, care must be taken
when giving users access to
commands via
sudo to verify that the
command does not inadvertently give the user
an effective root shell. For information on ways to address this, see the
Preventing shell escapes section in
sudoers(5).
To prevent the disclosure of potentially sensitive information,
sudo disables core dumps by default while it is
executing (they are re-enabled for the
command that is run). This historical
practice dates from a time when most operating systems allowed set-user-ID
processes to dump core by default. To aid in debugging
sudo crashes, you may wish to re-enable core
dumps by setting “disable_coredump” to false in the
sudo.conf(5) file as follows:
Set disable_coredump false
See the
sudo.conf(5) manual for more information.
sudo utilizes the following environment variables.
The security policy has control over the actual content of the
command's environment.
EDITOR
- Default editor to use in -e
(sudoedit) mode if neither
SUDO_EDITOR
nor VISUAL
is set.
MAIL
- Set to the mail spool of the target user when the
-i option is specified, or when
env_reset is enabled in
sudoers (unless
MAIL
is present in the
env_keep list).
HOME
- Set to the home directory of the target user when the
-i or -H options
are specified, when the -s option is
specified and set_home is set in
sudoers, when
always_set_home is enabled in
sudoers, or when
env_reset is enabled in
sudoers and
HOME
is not present in the
env_keep list.
LOGNAME
- Set to the login name of the target user when the
-i option is specified, when the
set_logname option is enabled in
sudoers, or when the
env_reset option is enabled in
sudoers (unless
LOGNAME
is present in the
env_keep list).
PATH
- May be overridden by the security policy.
SHELL
- Used to determine shell to run with
-s option.
SUDO_ASKPASS
- Specifies the path to a helper program used to read the
password if no terminal is available or if the
-A option is specified.
SUDO_COMMAND
- Set to the command run by
sudo, including any args. The
args are truncated at 4096 characters to
prevent a potential execution error.
SUDO_EDITOR
- Default editor to use in -e
(sudoedit) mode.
SUDO_GID
- Set to the group-ID of the user who invoked sudo.
SUDO_PROMPT
- Used as the default password prompt unless the
-p option was specified.
SUDO_PS1
- If set,
PS1
will be set
to its value for the program being run.
SUDO_UID
- Set to the user-ID of the user who invoked sudo.
SUDO_USER
- Set to the login name of the user who invoked sudo.
USER
- Set to the same value as
LOGNAME
, described above.
VISUAL
- Default editor to use in -e
(sudoedit) mode if
SUDO_EDITOR
is not
set.
- /etc/sudo.conf
-
sudo front-end
configuration
The following examples assume a properly configured security policy.
To get a file listing of an unreadable directory:
$ sudo ls /usr/local/protected
To list the home directory of user yaz on a machine where the file system
holding ~yaz is not exported as root:
To edit the
index.html file as user www:
$ sudoedit -u www ~www/htdocs/index.html
To view system logs only accessible to root and users in the adm group:
$ sudo -g adm more /var/log/syslog
To run an editor as jim with a different primary group:
$ sudoedit -u jim -g audio ~jim/sound.txt
To shut down a machine:
$ sudo shutdown -r +15 "quick reboot"
To make a usage listing of the directories in the /home partition. The
commands are run in a sub-shell to allow the
‘
cd
’ command and file redirection to
work.
$ sudo sh -c "cd /home ; du -s * | sort -rn > USAGE"
Error messages produced by
sudo include:
editing
files in a writable directory is not permitted
- By default, sudoedit does not
permit editing a file when any of the parent directories are writable by
the invoking user. This avoids a race condition that could allow the user
to overwrite an arbitrary file. See the
sudoedit_checkdir option in
sudoers(5) for more information.
editing
symbolic links is not permitted
- By default, sudoedit does not
follow symbolic links when opening files. See the
sudoedit_follow option in
sudoers(5) for more information.
effective
uid is not 0, is sudo installed setuid root?
-
sudo was not run with root
privileges. The sudo binary must be owned by
the root user and have the set-user-ID bit set. Also, it must not be
located on a file system mounted with the ‘nosuid’ option or
on an NFS file system that maps uid 0 to an unprivileged uid.
effective
uid is not 0, is sudo on a file system with the 'nosuid' option set or an
NFS file system without root privileges?
-
sudo was not run with root
privileges. The sudo binary has the proper
owner and permissions but it still did not run with root privileges. The
most common reason for this is that the file system the
sudo binary is located on is mounted with the
‘nosuid’ option or it is an NFS file system that maps uid 0
to an unprivileged uid.
fatal
error, unable to load plugins
- An error occurred while loading or initializing the plugins
specified in sudo.conf(5).
invalid
environment variable name
- One or more environment variable names specified via the
-E option contained an equal sign
(‘
=
’). The arguments to the
-E option should be environment variable
names without an associated value.
no
password was provided
- When sudo tried to read the
password, it did not receive any characters. This may happen if no
terminal is available (or the -S option is
specified) and the standard input has been redirected from
/dev/null.
a
terminal is required to read the password
-
sudo needs to read the
password but there is no mechanism available for it to do so. A terminal
is not present to read the password from,
sudo has not been configured to read from the
standard input, the -S option was not used,
and no askpass helper has been specified either via the
sudo.conf(5) file or the
SUDO_ASKPASS
environment variable.
no
writable temporary directory found
-
sudoedit was unable to find a
usable temporary directory in which to store its intermediate files.
-
The
“no new privileges” flag is set, which prevents sudo from
running as root.
-
sudo was run by a process that
has the Linux “no new privileges” flag is set. This causes
the set-user-ID bit to be ignored when running an executable, which will
prevent sudo from functioning. The most
likely cause for this is running sudo within
a container that sets this flag. Check the documentation to see if it is
possible to configure the container such that the flag is not set.
sudo
must be owned by uid 0 and have the setuid bit set
-
sudo was not run with root
privileges. The sudo binary does not have the
correct owner or permissions. It must be owned by the root user and have
the set-user-ID bit set.
sudoedit
is not supported on this platform
- It is only possible to run
sudoedit on systems that support setting the
effective user-ID.
timed
out reading password
- The user did not enter a password before the password
timeout (5 minutes by default) expired.
you
do not exist in the passwd database
- Your user-ID does not appear in the system passwd
database.
you
may not specify environment variables in edit mode
- It is only possible to specify environment variables when
running a command. When editing a file,
the editor is run with the user's environment unmodified.
su(1),
stat(2),
login_cap(3),
passwd(5),
sudo.conf(5),
sudo_plugin(5),
sudoers(5),
sudoers_timestamp(5),
sudoreplay(8),
visudo(8)
See the HISTORY.md file in the
sudo distribution
(
https://www.sudo.ws/about/history/) for a brief history of sudo.
Many people have worked on
sudo over the years;
this version consists of code written primarily by:
Todd C.
Miller
See the CONTRIBUTORS.md file in the
sudo
distribution (
https://www.sudo.ws/about/contributors/) for an exhaustive list
of people who have contributed to
sudo.
There is no easy way to prevent a user from gaining a root shell if that user is
allowed to run arbitrary
commands via
sudo. Also, many programs (such as editors) allow
the user to run
commands via shell escapes,
thus avoiding
sudo's checks. However, on most
systems it is possible to prevent shell escapes with the
sudoers(5) plugin's
noexec functionality.
It is not meaningful to run the ‘
cd
’
command directly via sudo, e.g.,
$ sudo cd /usr/local/protected
since when the
command exits the parent process
(your shell) will still be the same. The
-D
option can be used to run a
command in a
specific
directory.
Running shell scripts via
sudo can expose the same
kernel bugs that make set-user-ID shell scripts unsafe on some operating
systems (if your OS has a /dev/fd/ directory, set-user-ID shell scripts are
generally safe).
If you believe you have found a bug in
sudo, you
can submit a bug report at
https://bugzilla.sudo.ws/
Limited free support is available via the sudo-users mailing list, see
https://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the
archives.
sudo is provided “AS IS” and any
express or implied warranties, including, but not limited to, the implied
warranties of merchantability and fitness for a particular purpose are
disclaimed. See the LICENSE.md file distributed with
sudo or
https://www.sudo.ws/about/license/ for
complete details.