Linux command visudo

edits the

file in a safe fashion, analogous to

locks the

file against multiple simultaneous edits, performs basic validity checks, and checks for syntax errors before installing the edited file. If the

file is currently being edited you will receive a message to try again later.

parses the

file after editing and will not save the changes if there is a syntax error. Upon finding an error,

will print a message stating the line number(s) where the error occurred and the user will receive the

prompt. At this point the user may enter

to re-edit the

file,

to exit without saving the changes, or

to quit and save changes. The

option should be used with extreme caution because if

believes there to be a syntax error, so will

and no one will be able to run

again until the error is fixed. If

is typed to edit the

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

settings that determine which editor

will run.

A colon

separated list of editors allowed to be used with

will choose the editor that matches the user's

environment variable if possible, or the first editor in the list that exists and is executable. Note that

does not preserve the

environment variables unless they are present in the

list or the

option is disabled in the

file. The default editor path is

which can be set at compile time via the

configure option.

If set,

will use the value of the

environment variables before falling back on the default editor list. Note that

is typically run as root so this option may allow a user with

privileges to run arbitrary commands as root without logging. An alternative is to place a colon-separated list of

editors int the

variable.

will then only use

if they match a value specified in

If the

flag is enabled, the

and/or

environment variables must be present in the

list for the

flag to function when

is invoked via

The default value is

which can be set at compile time via the

configure option.

The options are as follows:

Enable

mode. The existing

file (and any other files it includes) will be checked for syntax errors. If the path to the

file was not specified,

will also check the file owner and mode. A message will be printed to the standard output describing the status of

unless the

option was specified. If the check completes successfully,

will exit with a value of 0. If an error is encountered,

will exit with a value of 1.

Specify an alternate

file location, see below. As of version 1.8.27, the

path can be specified without using the

option.

Display a short help message to the standard output and exit.

Enable

mode. In this mode details about syntax errors are not printed. This option is only useful when combined with the

option.

Enable

checking of the

file. If an alias is referenced but not actually defined or if there is a cycle in an alias,

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.

Print the

and

grammar versions and exit.

file may be specified instead of the default,

The temporary file used is the specified

file with

appended to it. In

mode only,

may be used to indicate that

will be read from the standard input. Because the policy is evaluated in its entirety, it is not sufficient to check an individual

include file for syntax errors.

versions 1.8.4 and higher support a flexible debugging framework that is configured via

lines in the

file.

Starting with

1.8.12,

will also parse the arguments to the

plugin to override the default

path name, UID, GID and file mode. These arguments, if present, should be listed after the path to the plugin (i.e., after

Multiple arguments may be specified, separated by white space. For example:

Plugin sudoers_policy sudoers.so sudoers_mode=0400

The following arguments are supported:

The

argument can be used to override the default path to the

file.

The

argument can be used to override the default owner of the sudoers file. It should be specified as a numeric user-ID.

The

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).

The

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

please refer to its manual.

The following environment variables may be consulted depending on the value of the

and

settings:

Invoked by

as the editor to use

Used by

is not set

Used by

if neither

nor

is set

Sudo front end configuration

List of who can run what

Default temporary file used by visudo

In addition to reporting

syntax errors,

may produce the following messages:

Someone else is currently editing the

file.

You didn't run

as root.

Your user-ID does not appear in the system passwd database.

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

will not complain

The message is prefixed with the path name of the

file and the line number where the undefined alias was used. In

(strict) mode these are errors, not warnings.

The specified {User,Runas,Host,Cmnd}_Alias was defined but never used. The message is prefixed with the path name of the

file and the line number where the unused alias was defined. You may wish to comment out or remove the unused 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

file and the line number where the cycle was detected. This is only a warning unless

is run in

(strict) mode as

will ignore cycles when parsing the

file.

The

file contains a

setting not recognized by

Many people have worked on

over the years; this version consists of code written primarily by:

See the CONTRIBUTORS file in the

distribution (https://www.sudo.ws/contributors.html) for an exhaustive list of people who have contributed to

There is no easy way to prevent a user from gaining a root shell if the editor used by

allows shell escapes.

If you feel you have found a bug in

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.

is provided

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

or https://www.sudo.ws/license.html for complete details.