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VISUDO(8) BSD System Manager's Manual VISUDO(8)
visudo — edit the sudoers file
visudo [-chqsV] [[-f] sudoers]
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 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
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).
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
possible, or the first editor in the list that exists and is
executable. 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
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 alter‐
native 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 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, see below. As
of version 1.8.27, the sudoers path can be specified with‐
out using the -f option.
-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 upper‐
case 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 individ‐
ual 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, 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
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=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.
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
/etc/sudo.conf Sudo front end configuration
/etc/sudoers List of who can run what
/etc/sudoers.tmp Default temporary file used by visudo
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: 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
underscore (‘_’) 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
message 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.
vi(1), sudo.conf(5), sudoers(5), sudo(8), vipw(8)
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 peo‐
ple who have contributed to sudo.
There is no easy way to prevent a user from gaining a root shell if the
editor used by visudo allows shell escapes.
If you feel you have found a bug in visudo, please 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.
visudo is provided “AS IS” and any express or implied warranties,
including, but not limited to, the implied warranties of merchantabil‐
ity and fitness for a particular purpose are disclaimed. See the
LICENSE file distributed with sudo or https://www.sudo.ws/license.html
for complete details.
This page is part of the sudo (execute a command as another user)
project. Information about the project can be found at
https://www.sudo.ws/. If you have a bug report for this manual page,
see ⟨https://bugzilla.sudo.ws/⟩. This page was obtained from the
project's upstream Git repository
⟨https://github.com/sudo-project/sudo⟩ on 2020-08-13. (At that time,
the date of the most recent commit that was found in the repository was
2020-08-12.) If you discover any rendering problems in this HTML ver‐
sion of the page, or you believe there is a better or more up-to-date
source for the page, or you have corrections or improvements to the
information in this COLOPHON (which is not part of the original manual
page), send a mail to man-pages@man7.org
Sudo 1.9.2 October 20, 2019 Sudo 1.9.2