Copyright (c) 1996,1998-2005, 2007-2012
Todd C. Miller <Todd.Miller@courtesan.com>
Permission to use, copy, modify, and distribute this software for any
purpose with or without fee is hereby granted, provided that the above
copyright notice and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Sponsored in part by the Defense Advanced Research Projects
Agency (DARPA) and Air Force Research Laboratory, Air Force
Materiel Command, USAF, under agreement number F39502-99-1-0512.
.Dd July 12, 2012 .Dt VISUDO @mansectsu@ .Os Sudo @PACKAGE_VERSION@ .Sh NAME .Nm visudo .Nd edit the sudoers file .Sh SYNOPSIS .Nm visudo .Op Fl chqsV k -words .Op Fl f Ar sudoers .Ek .Sh DESCRIPTION .Nm visudo edits the .Em sudoers file in a safe fashion, analogous to .Xr vipw @mansectsu@ . .Nm visudo locks the .Em sudoers file against multiple simultaneous edits, provides basic sanity checks, and checks for parse errors. If the .Em sudoers file is currently being edited you will receive a message to try again later.
p There is a hard-coded list of one or more editors that .Nm visudo will use set at compile-time that may be overridden via the .Em editor .Em sudoers .Li Default variable. This list defaults to .Li "@editor@" . Normally, .Nm visudo does not honor the .Ev VISUAL or .Ev EDITOR environment variables unless they contain an editor in the aforementioned editors list. However, if .Nm visudo is configured with the .Li --with-env-editor option or the .Em env_editor .Li Default variable is set in .Em sudoers , .Nm visudo will use any the editor defines by .Ev VISUAL or .Ev EDITOR . Note that this can be a security hole since it allows the user to execute any program they wish simply by setting .Ev VISUAL or .Ev EDITOR .
p .Nm visudo parses the .Em sudoers file after the edit and will not save the changes if there is a syntax error. Upon finding an error, .Nm visudo will print a message stating the line number(s) where the error occurred and the user will receive the .Dq What now? prompt. At this point the user may enter .Ql e to re-edit the .Em sudoers file, .Ql x to exit without saving the changes, or .Ql Q to quit and save changes. The .Ql Q option should be used with extreme care because if .Nm visudo believes there to be a parse error, so will .Nm sudo and no one will be able to .Nm sudo again until the error is fixed. If .Ql e is typed to edit the .Em 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).
p The options are as follows: l -tag -width Fl t Fl c Enable .Em check-only mode. The existing .Em sudoers file will be checked for syntax errors, owner and mode. A message will be printed to the standard output describing the status of .Em sudoers unless the .Fl q option was specified. If the check completes successfully, .Nm visudo will exit with a value of 0. If an error is encountered, .Nm visudo will exit with a value of 1. t Fl f Ar sudoers Specify and alternate .Em sudoers file location. With this option .Nm visudo will edit (or check) the .Em sudoers file of your choice, instead of the default,
a @sysconfdir@/sudoers . The lock file used is the specified .Em sudoers file with .Dq \.tmp appended to it. In .Em check-only mode only, the argument to .Fl f may be .Ql - , indicating that .Em sudoers will be read from the standard input. t Fl h The .Fl h No ( Em help Ns No ) option causes .Nm visudo to print a short help message to the standard output and exit. t Fl q Enable .Em quiet mode. In this mode details about syntax errors are not printed. This option is only useful when combined with the .Fl c option. t Fl s Enable .Em strict checking of the .Em sudoers file. If an alias is used before it is defined, .Nm 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 uppercase letters, digits, and the underscore
q Ql _ character. t Fl V The .Fl V ( Em version Ns No ) option causes .Nm visudo to print its version number and exit. .El .Sh ENVIRONMENT The following environment variables may be consulted depending on the value of the .Em editor and .Em env_editor .Em sudoers settings: l -tag -width 15n t Ev VISUAL Invoked by .Nm visudo as the editor to use t Ev EDITOR Used by .Nm visudo if .Ev VISUAL is not set .El .Sh FILES l -tag -width 24n t Pa @sysconfdir@/sudoers List of who can run what t Pa @sysconfdir@/sudoers.tmp Lock file for visudo .El .Sh DIAGNOSTICS l -tag -width 4n t Li sudoers file busy, try again later. Someone else is currently editing the .Em sudoers file. t Li @sysconfdir@/sudoers.tmp: Permission denied You didn't run .Nm visudo as root. t Li Can't find you in the passwd database Your user ID does not appear in the system passwd file. t Li 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
q Ql _ character. In the latter case, you can ignore the warnings
o .Nm sudo will not complain
c . In .Fl s (strict) mode these are errors, not warnings. t Li Warning: unused {User,Runas,Host,Cmnd}_Alias The specified {User,Runas,Host,Cmnd}_Alias was defined but never used. You may wish to comment out or remove the unused alias. In .Fl s (strict) mode this is an error, not a warning. t Li 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. This is only a warning by default as .Nm sudo will ignore cycles when parsing the .Em sudoers file. .El .Sh SEE ALSO .Xr vi 1 , .Xr sudoers @mansectform@ , .Xr sudo @mansectsu@ , .Xr vipw @mansectsu@ .Sh AUTHORS Many people have worked on .Nm sudo over the years; this version consists of code written primarily by: d -ragged -offset indent Todd C. Miller .Ed
p See the CONTRIBUTORS file in the .Nm sudo distribution (http://www.sudo.ws/sudo/contributors.html) for an exhaustive list of people who have contributed to .Nm sudo . .Sh CAVEATS There is no easy way to prevent a user from gaining a root shell if the editor used by .Nm visudo allows shell escapes. .Sh BUGS If you feel you have found a bug in .Nm visudo , please submit a bug report at http://www.sudo.ws/sudo/bugs/ .Sh SUPPORT Limited free support is available via the sudo-users mailing list, see http://www.sudo.ws/mailman/listinfo/sudo-users to subscribe or search the archives. .Sh DISCLAIMER .Nm visudo is provided .Dq 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 .Nm sudo or http://www.sudo.ws/sudo/license.html for complete details.