visudo - edit the sudoers file
visudo [-chOPqsV] [[-f] sudoers]
VISUDO(8) BSD System Manager's Manual VISUDO(8)
NAME
visudo -- edit the sudoers file
SYNOPSIS
visudo [-chOPqsV] [[-f] sudoers]
DESCRIPTION
visudo edits the sudoers file in a safe fashion, analogous to vipw(8).
visudo locks the sudoers file against multiple simultaneous edits, per-
forms basic validity checks, and checks for syntax errors before
installing the edited file. If the sudoers file is currently being
edited you will receive a message to try again later.
visudo parses the sudoers file after editing 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 caution because if visudo believes there to be a syntax
error, so will sudo. If `e' is typed to edit the sudoers file after a
syntax error has been detected, the cursor will be placed on the line
where the error occurred (if the editor supports this feature).
There are two sudoers settings that determine which editor visudo will
run.
editor A colon (`:') separated list of editors allowed to be used with
visudo. visudo will choose the editor that matches the user's
SUDO_EDITOR, VISUAL, or EDITOR environment variable if possi-
ble, or the first editor in the list that exists and is exe-
cutable. Note that sudo does not preserve the SUDO_EDITOR,
VISUAL, or EDITOR environment variables unless they are present
in the env_keep list or the env_reset option is disabled in the
sudoers file. The default editor path is /usr/bin/vi which can
be set at compile time via the --with-editor configure option.
env_editor
If set, visudo will use the value of the SUDO_EDITOR, VISUAL,
or EDITOR environment variables before falling back on the
default editor list. Note that visudo is typically run as root
so this option may allow a user with visudo privileges to run
arbitrary commands as root without logging. An alternative is
to place a colon-separated list of ``safe'' editors int the
editor variable. visudo will then only use SUDO_EDITOR,
VISUAL, or EDITOR if they match a value specified in editor.
If the env_reset flag is enabled, the SUDO_EDITOR, VISUAL,
and/or EDITOR environment variables must be present in the
env_keep list for the env_editor flag to function when visudo
is invoked via sudo. The default value is on, which can be set
at compile time via the --with-env-editor configure option.
The options are as follows:
-c, --check
Enable check-only mode. The existing sudoers file (and any
other files it includes) will be checked for syntax errors.
If the path to the sudoers file was not specified, visudo
will also check the file ownership and permissions (see the
-O and -P options). A message will be printed to the stan-
dard 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 encoun-
tered, visudo will exit with a value of 1.
-f sudoers, --file=sudoers
Specify an alternate sudoers file location, see below. As of
version 1.8.27, the sudoers path can be specified without
using the -f option.
-h, --help Display a short help message to the standard output and exit.
-O, --owner
Enforce the default ownership (user and group) of the sudoers
file. In edit mode, the owner of the edited file will be set
to the default. In check mode (-c), an error will be
reported if the owner is incorrect. This option is enabled
by default if the sudoers file was not specified.
-P, --perms
Enforce the default permissions (mode) of the sudoers file.
In edit mode, the permissions of the edited file will be set
to the default. In check mode (-c), an error will be
reported if the file permissions are incorrect. This option
is enabled by default if the sudoers file was not specified.
-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 syntax error. Note
that it is not possible to differentiate between an alias and
a host name or user name that consists solely of uppercase
letters, digits, and the underscore (`_') character.
-V, --version
Print the visudo and sudoers grammar versions and exit.
A sudoers file may be specified instead of the default, /etc/sudoers.
The temporary file used is the specified sudoers file with ``.tmp''
appended to it. In check-only mode only, `-' may be used to indicate
that sudoers will be read from the standard input. Because the policy is
evaluated in its entirety, it is not sufficient to check an individual
sudoers include file for syntax errors.
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, user-ID, group-
ID, 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 specified, 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=user-ID
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=group-ID
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:
SUDO_EDITOR Invoked by visudo as the editor to use
VISUAL Used by visudo if SUDO_EDITOR is not set
EDITOR Used by visudo if neither SUDO_EDITOR nor VISUAL is set
FILES
/etc/sudo.conf Sudo front-end configuration
/etc/sudoers List of who can run what
/etc/sudoers.tmp Default temporary file used by visudo
DIAGNOSTICS
In addition to reporting sudoers syntax errors, visudo may produce the
following messages:
sudoers file busy, try again later.
Someone else is currently editing the sudoers file.
/etc/sudoers: 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.
ATTRIBUTES
See attributes(7) for descriptions of the following attributes:
+---------------+-----------------------+
|ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+---------------+-----------------------+
|Availability | security/sudo |
+---------------+-----------------------+
|Stability | Pass-through volatile |
+---------------+-----------------------+
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.
NOTES
Source code for open source software components in Oracle Solaris can be
found at https://www.oracle.com/downloads/opensource/solaris-source-code-
downloads.html.
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-1.9.9.tar.gz.
Further information about this software can be found on the open source
community website at https://www.sudo.ws/.
Sudo 1.9.9 January 20, 2022 Sudo 1.9.9