SUDO
Section: Maintenance Commands (8)
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BSD mandoc
Sudo 1.9.13p3
NAME
sudo
sudoedit
- execute a command as another user
SYNOPSIS
sudo
-h | K | k | V
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 ...
DESCRIPTION
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
Sx 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.conf5
contains a line specifying the askpass program, that value will be
used.
For example:
# Path to askpass helper program
Path askpass /usr/X11R6/bin/ssh-askpass
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
command s
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
file s
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
command s
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
command s.
The
sudoers
plugin does not currently support running remote
command s.
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
arg s
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
arg s.
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
arg s
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
command s 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.
COMMAND EXECUTION
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)
Process model
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.
Signal handling
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
Fn exec
family of functions instead of
Fn system
(which interposes a shell between the
command
and the calling process).
Plugins
Plugins may be specified via
Plugin
directives in the
sudo.conf5
file.
They may be loaded as dynamic shared objects (on systems that support them),
or compiled directly into the
sudo
binary.
If no
sudo.conf5
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.conf5
manual for details of the
/etc/sudo.conf
file and the
sudo_plugin5
manual for more information about the
sudo
plugin architecture.
EXIT VALUE
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.
SECURITY NOTES
sudo
tries to be safe when executing external
command s.
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
command s
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
command s
run from that shell are not subject to
sudo 's
security policy.
The same is true for
command s
that offer shell escapes (including most editors).
If I/O logging is enabled, subsequent
command s
will have their input and/or output logged, but there will not be
traditional logs for those
command s.
Because of this, care must be taken when giving users access to
command s
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.conf5
file as follows:
Set disable_coredump false
See the
sudo.conf5
manual for more information.
ENVIRONMENT
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
arg s.
The
arg s
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.
FILES
- /etc/sudo.conf
-
sudo
front-end configuration
EXAMPLES
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:
$ sudo -u yaz ls ~yaz
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"
DIAGNOSTICS
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.conf5.
- 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.conf5
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 Do no new privileges Dc 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.
SEE ALSO
su(1),
stat(2),
login_cap3,
passwd(5),
sudo.conf5,
sudo_plugin5,
sudoers(5),
sudoers_timestamp5,
sudoreplay(8),
visudo(8)
HISTORY
See the HISTORY.md file in the
sudo
distribution (https://www.sudo.ws/about/history/) for a brief
history of sudo.
AUTHORS
Many people have worked on
sudo
over the years; this version consists of code written primarily by:
An 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.
CAVEATS
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
command s
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).
BUGS
If you believe you have found a bug in
sudo,
you can submit a bug report at https://bugzilla.sudo.ws/
SUPPORT
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.
DISCLAIMER
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.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- COMMAND EXECUTION
-
- Process model
-
- Signal handling
-
- Plugins
-
- EXIT VALUE
-
- SECURITY NOTES
-
- ENVIRONMENT
-
- FILES
-
- EXAMPLES
-
- DIAGNOSTICS
-
- SEE ALSO
-
- HISTORY
-
- AUTHORS
-
- CAVEATS
-
- BUGS
-
- SUPPORT
-
- DISCLAIMER
-
This document was created by
man2html,
using the manual pages.
Time: 17:30:17 GMT, April 23, 2024