VISUDO(8) System Manager's Manual VISUDO(8)
NAME
visudo - edit the sudoers file
SYNOPSIS
visudo [-chIOPqsV] [[-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,
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. 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. 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. 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 in 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 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.
-I, --no-includes
Disable the editing of include files unless there is a pre-
existing syntax error. By default, visudo will edit the main
sudoers file and any files included via @include or #include
directives. Files included via @includedir or #includedir are
never edited unless they contain a syntax error.
-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. 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,
/private/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), 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
/private/etc/sudo.conf Sudo front-end configuration
/private/etc/sudoers List of who can run what
/private/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.
/private/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.
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.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 the
editor used by visudo allows shell escapes.
BUGS
If you believe you have found a bug in visudo, 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
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.md file distributed with sudo or
https://www.sudo.ws/about/license/ for complete details.
Sudo 1.9.13p2 January 16, 2023 VISUDO(8)