visudo - edit the sudoers file
visudo [-chqsV] [-f sudoers] [-x output_file]
VISUDO(8) BSD System Manager's Manual VISUDO(8)
NAME
visudo -- edit the sudoers file
SYNOPSIS
visudo [-chqsV] [-f sudoers] [-x output_file]
DESCRIPTION
visudo edits the sudoers file in a safe fashion, analogous to vipw(8).
visudo locks the sudoers file against multiple simultaneous edits, pro-
vides basic sanity checks, and checks for parse errors. If the sudoers
file is currently being edited you will receive a message to try again
later.
There is a hard-coded list of one or more editors that visudo will use
set at compile-time that may be overridden via the editor sudoers Default
variable. This list defaults to vi. Normally, visudo does not honor the
VISUAL or EDITOR environment variables unless they contain an editor in
the aforementioned editors list. However, if visudo is configured with
the --with-env-editor option or the env_editor Default variable is set in
sudoers, visudo will use any the editor defines by VISUAL or EDITOR.
Note that this can be a security hole since it allows the user to execute
any program they wish simply by setting VISUAL or EDITOR.
visudo parses the sudoers file after the edit and will not save the
changes if there is a syntax error. Upon finding an error, visudo will
print a message stating the line number(s) where the error occurred and
the user will receive the ``What now?'' prompt. At this point the user
may enter `e' to re-edit the sudoers file, `x' to exit without saving the
changes, or `Q' to quit and save changes. The `Q' option should be used
with extreme care because if visudo believes there to be a parse error,
so will sudo and no one will be able to run sudo again until the error is
fixed. If `e' is typed to edit the sudoers file after a parse error has
been detected, the cursor will be placed on the line where the error
occurred (if the editor supports this feature).
The options are as follows:
-c, --check
Enable check-only mode. The existing sudoers file will be
checked for syntax errors, owner and mode. A message will be
printed to the standard output describing the status of
sudoers unless the -q option was specified. If the check
completes successfully, visudo will exit with a value of 0.
If an error is encountered, visudo will exit with a value of
1.
-f sudoers, --file=sudoers
Specify an alternate sudoers file location. With this
option, visudo will edit (or check) the sudoers file of your
choice, instead of the default, /etc/sudoers. The lock file
used is the specified sudoers file with ``.tmp'' appended to
it. In check-only mode only, the argument to -f may be `-',
indicating that sudoers will be read from the standard input.
-h, --help Display a short help message to the standard output and exit.
-q, --quiet
Enable quiet mode. In this mode details about syntax errors
are not printed. This option is only useful when combined
with the -c option.
-s, --strict
Enable strict checking of the sudoers file. If an alias is
referenced but not actually defined or if there is a cycle in
an alias, visudo will consider this a parse error. Note that
it is not possible to differentiate between an alias and a
host name or user name that consists solely of uppercase let-
ters, digits, and the underscore (`_') character.
-V, --version
Print the visudo and sudoers grammar versions and exit.
-x output_file, --export=output_file
Export a sudoers in JSON format and write it to output_file.
If output_file is `-', the exported sudoers policy will be
written to the standard output. By default, /etc/sudoers
(and any files it includes) will be exported. The -f option
can be used to specify a different sudoers file to export.
The exported format is intended to be easier for third-party
applications to parse than the traditional sudoers format.
The various values have explicit types which removes much of
the ambiguity of the sudoers format.
Debugging and sudoers plugin arguments
visudo versions 1.8.4 and higher support a flexible debugging framework
that is configured via Debug lines in the sudo.conf(5) file.
Starting with sudo 1.8.12, visudo will also parse the arguments to the
sudoers plugin to override the default sudoers path name, UID, GID and
file mode. These arguments, if present, should be listed after the path
to the plugin (i.e. after sudoers.so). Multiple arguments may be speci-
fied, separated by white space. For example:
Plugin sudoers_policy sudoers.so sudoers_mode=0400
The following arguments are supported:
sudoers_file=pathname
The sudoers_file argument can be used to override the default
path to the sudoers file.
sudoers_uid=uid
The sudoers_uid argument can be used to override the default
owner of the sudoers file. It should be specified as a numeric
user ID.
sudoers_gid=gid
The sudoers_gid argument can be used to override the default
group of the sudoers file. It must be specified as a numeric
group ID (not a group name).
sudoers_mode=mode
The sudoers_mode argument can be used to override the default
file mode for the sudoers file. It should be specified as an
octal value.
For more information on configuring sudo.conf(5), please refer to its
manual.
ENVIRONMENT
The following environment variables may be consulted depending on the
value of the editor and env_editor sudoers settings:
VISUAL Invoked by visudo as the editor to use
EDITOR Used by visudo if VISUAL is not set
FILES
/etc/sudo.conf Sudo front end configuration
/etc/sudoers List of who can run what
/etc/sudoers.tmp Lock file for visudo
DIAGNOSTICS
In addition to reporting sudoers parse errors, visudo may produce the
following messages:
sudoers file busy, try again later.
Someone else is currently editing the sudoers file.
/etc/sudoers.tmp: Permission denied
You didn't run visudo as root.
you do not exist in the passwd database
Your user ID does not appear in the system passwd database.
Warning: {User,Runas,Host,Cmnd}_Alias referenced but not defined
Either you are trying to use an undeclared
{User,Runas,Host,Cmnd}_Alias or you have a user or host name listed
that consists solely of uppercase letters, digits, and the under-
score (`_') character. In the latter case, you can ignore the
warnings (sudo will not complain). The message is prefixed with
the path name of the sudoers file and the line number where the
undefined alias was used. In -s (strict) mode these are errors,
not warnings.
Warning: unused {User,Runas,Host,Cmnd}_Alias
The specified {User,Runas,Host,Cmnd}_Alias was defined but never
used. The message is prefixed with the path name of the sudoers
file and the line number where the unused alias was defined. You
may wish to comment out or remove the unused alias.
Warning: cycle in {User,Runas,Host,Cmnd}_Alias
The specified {User,Runas,Host,Cmnd}_Alias includes a reference to
itself, either directly or through an alias it includes. The mes-
sage is prefixed with the path name of the sudoers file and the
line number where the cycle was detected. This is only a warning
unless visudo is run in -s (strict) mode as sudo will ignore cycles
when parsing the sudoers file.
unknown defaults entry "name"
The sudoers file contains a Defaults setting not recognized by
visudo.
/etc/sudoers: input and output files must be different
The -x flag was used and the specified output_file has the same
path name as the sudoers file to export.
See for descriptions of the following attributes:
+---------------+------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+------------------+
|Availability | security/sudo |
+---------------+------------------+
|Stability | Uncommitted |
+---------------+------------------+
SEE ALSO
vi(1), sudo.conf(5), sudoers(5), sudo(8), vipw(8)
AUTHORS
Many people have worked on sudo over the years; this version consists of
code written primarily by:
Todd C. Miller
See the CONTRIBUTORS file in the sudo distribution
(https://www.sudo.ws/contributors.html) 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 the
editor used by visudo allows shell escapes.
BUGS
If you feel you have found a bug in visudo, please 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
visudo 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
file distributed with sudo or https://www.sudo.ws/license.html for com-
plete details.
This software was built from source available at https://github.com/ora-
cle/solaris-userland. The original community source was downloaded from
https://www.sudo.ws/sudo/dist/sudo-1.8.21p2.tar.gz
Further information about this software can be found on the open source
community website at https://www.sudo.ws/.
Sudo 1.8.21p2 February 22, 2017 Sudo 1.8.21p2