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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, performs 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 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 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 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 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 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
without 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 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, 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 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 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
people 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
merchantability 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 2020-12-18. (At that
time, the date of the most recent commit that was found in the
repository was 2020-12-15.) If you discover any rendering problems
in this HTML version 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 1.9.4p1 August 27, 2020 Sudo 1.9.4p1
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