path: root/usr.bin/sudo/visudo.8

.\" Copyright (c) 1996,1998-2003 Todd C. Miller <Todd.Miller@courtesan.com>
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.\" Materiel Command, USAF, under agreement number F39502-99-1-0512.
.\" 
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.\" ========================================================================
.\"
.IX Title "VISUDO 8"
.TH VISUDO 8 "June 20, 2005" "1.6.8p9" "MAINTENANCE COMMANDS"
.SH "NAME"
visudo \- edit the sudoers file
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
\&\fBvisudo\fR [ \fB\-c\fR ] [ \fB\-f\fR \fIsudoers\fR ] [ \fB\-q\fR ] [ \fB\-s\fR ] [ \fB\-V\fR ]
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBvisudo\fR edits the \fIsudoers\fR file in a safe fashion, analogous to
vipw(8).  \fBvisudo\fR locks the \fIsudoers\fR file against multiple
simultaneous edits, provides basic sanity checks, and checks
for parse errors.  If the \fIsudoers\fR file is currently being
edited you will receive a message to try again later.
.PP
There is a hard-coded list of editors that \fBvisudo\fR will use set
at compile-time that may be overridden via the \fIeditor\fR \fIsudoers\fR
\&\f(CW\*(C`Default\*(C'\fR variable.  This list defaults to the path to \fIvi\fR\|(1) on
your system, as determined by the \fIconfigure\fR script.  Normally,
\&\fBvisudo\fR does not honor the \f(CW\*(C`VISUAL\*(C'\fR or \f(CW\*(C`EDITOR\*(C'\fR environment
variables unless they contain an editor in the aforementioned editors
list.  However, if \fBvisudo\fR is configured with the \fI\-\-with\-enveditor\fR
flag or the \fIenveditor\fR \f(CW\*(C`Default\*(C'\fR variable is set in \fIsudoers\fR,
\&\fBvisudo\fR will use any the editor defines by \f(CW\*(C`VISUAL\*(C'\fR or \f(CW\*(C`EDITOR\*(C'\fR.
Note that this can be a security hole since it allows the user to
execute any program they wish simply by setting \f(CW\*(C`VISUAL\*(C'\fR or \f(CW\*(C`EDITOR\*(C'\fR.
.PP
\&\fBvisudo\fR parses the \fIsudoers\fR file after the edit and will
not save the changes if there is a syntax error.  Upon finding
an error, \fBvisudo\fR will print a message stating the line number(s)
where the error occurred and the user will receive the
\&\*(L"What now?\*(R" prompt.  At this point the user may enter \*(L"e\*(R"
to re-edit the \fIsudoers\fR file, \*(L"x\*(R" to exit without
saving the changes, or \*(L"Q\*(R" to quit and save changes.  The
\&\*(L"Q\*(R" option should be used with extreme care because if \fBvisudo\fR
believes there to be a parse error, so will \fBsudo\fR and no one
will be able to \fBsudo\fR again until the error is fixed.
If \*(L"e\*(R" is typed to edit the  \fIsudoers\fR 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).
.SH "OPTIONS"
.IX Header "OPTIONS"
\&\fBvisudo\fR accepts the following command line options:
.IP "\-c" 4
.IX Item "-c"
Enable \fBcheck-only\fR mode.  The existing \fIsudoers\fR file will be
checked for syntax and a message will be printed to the
standard output detailing the status of \fIsudoers\fR.
If the syntax check completes successfully, \fBvisudo\fR will
exit with a value of 0.  If a syntax error is encountered,
\&\fBvisudo\fR will exit with a value of 1.
.IP "\-f" 4
.IX Item "-f"
Specify and alternate \fIsudoers\fR file location.  With this option
\&\fBvisudo\fR will edit (or check) the \fIsudoers\fR file of your choice,
instead of the default, \fI/etc/sudoers\fR.  The lock file used
is the specified \fIsudoers\fR file with \*(L".tmp\*(R" appended to it.
.IP "\-q" 4
.IX Item "-q"
Enable \fBquiet\fR mode.  In this mode details about syntax errors
are not printed.  This option is only useful when combined with
the \fB\-c\fR flag.
.IP "\-s" 4
.IX Item "-s"
Enable \fBstrict\fR checking of the \fIsudoers\fR file.  If an alias is
used before it is defined, \fBvisudo\fR will consider this a parse
error.  Note that it is not possible to differentiate between an
alias and a hostname or username that consists solely of uppercase
letters, digits, and the underscore ('_') character.
.IP "\-V" 4
.IX Item "-V"
The \fB\-V\fR (version) option causes \fBvisudo\fR to print its version number
and exit.
.SH "ENVIRONMENT"
.IX Header "ENVIRONMENT"
The following environment variables are used only if \fBvisudo\fR
was configured with the \fI\-\-with\-env\-editor\fR option:
.PP
.Vb 2
\& VISUAL                 Invoked by visudo as the editor to use
\& EDITOR                 Used by visudo if VISUAL is not set
.Ve
.SH "FILES"
.IX Header "FILES"
.Vb 2
\& /etc/sudoers           List of who can run what
\& /etc/sudoers.tmp       Lock file for visudo
.Ve
.SH "DIAGNOSTICS"
.IX Header "DIAGNOSTICS"
.IP "sudoers file busy, try again later." 4
.IX Item "sudoers file busy, try again later."
Someone else is currently editing the \fIsudoers\fR file.
.IP "/etc/sudoers.tmp: Permission denied" 4
.IX Item "/etc/sudoers.tmp: Permission denied"
You didn't run \fBvisudo\fR as root.
.IP "Can't find you in the passwd database" 4
.IX Item "Can't find you in the passwd database"
Your userid does not appear in the system passwd file.
.IP "Warning: undeclared Alias referenced near ..." 4
.IX Item "Warning: undeclared Alias referenced near ..."
Either you are using a {User,Runas,Host,Cmnd}_Alias before
defining it or you have a user or hostname listed that
consists solely of uppercase letters, digits, and the
underscore ('_') character.  If the latter, you can ignore
the warnings (\fBsudo\fR will not complain).  In \fB\-s\fR (strict)
mode these are errors, not warnings.
.IP "Warning: runas_default set after old value is in use ..." 4
.IX Item "Warning: runas_default set after old value is in use ..."
You have a \fIrunas_default\fR Defaults setting listed in the \fIsudoers\fR
file after its value has already been used.  This means that entries
prior to the \fIrunas_default\fR setting will match based on the default
value of \fIrunas_default\fR (\f(CW\*(C`root\*(C'\fR) whereas entries
\&\fBafter\fR the \fIrunas_default\fR setting will match based on the new
value.  This is usually unintentional and in most cases the
<runas_default> setting should be placed before any \f(CW\*(C`Runas_Alias\*(C'\fR
or User specifications.  In \fB\-s\fR (strict) mode this is an error,
not a warning.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIvi\fR\|(1), sudoers(5), sudo(8), vipw(8)
.SH "AUTHOR"
.IX Header "AUTHOR"
Many people have worked on \fIsudo\fR over the years; this version of
\&\fBvisudo\fR was written by:
.PP
.Vb 1
\& Todd Miller
.Ve
.PP
See the \s-1HISTORY\s0 file in the sudo distribution or visit
http://www.sudo.ws/sudo/history.html for more details.
.SH "CAVEATS"
.IX Header "CAVEATS"
There is no easy way to prevent a user from gaining a root shell if 
the editor used by \fBvisudo\fR allows shell escapes.
.SH "BUGS"
.IX Header "BUGS"
If you feel you have found a bug in \fBvisudo\fR, please submit a bug report
at http://www.sudo.ws/sudo/bugs/
.SH "SUPPORT"
.IX Header "SUPPORT"
Commercial support is available for \fBsudo\fR, see
http://www.sudo.ws/sudo/support.html for details.
.PP
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"
.IX Header "DISCLAIMER"
\&\fBVisudo\fR is provided ``\s-1AS\s0 \s-1IS\s0'' 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 \s-1LICENSE\s0
file distributed with \fBsudo\fR or http://www.sudo.ws/sudo/license.html
for complete details.