140 lines
3.6 KiB
Groff
140 lines
3.6 KiB
Groff
.\" Title: su
|
|
.\" Author:
|
|
.\" Generator: DocBook XSL Stylesheets v1.70.1 <http://docbook.sf.net/>
|
|
.\" Date: 06/06/2006
|
|
.\" Manual: User Commands
|
|
.\" Source: User Commands
|
|
.\"
|
|
.TH "SU" "1" "06/06/2006" "User Commands" "User Commands"
|
|
.\" disable hyphenation
|
|
.nh
|
|
.\" disable justification (adjust text to left margin only)
|
|
.ad l
|
|
.SH "NAME"
|
|
su \- change user ID or become super\-user
|
|
.SH "SYNOPSIS"
|
|
.HP 3
|
|
\fBsu\fR [\fIoptions\fR] [\-] [\fIusername\fR\ [\ \fIargs\fR\ ]]
|
|
.SH "DESCRIPTION"
|
|
.PP
|
|
|
|
\fBsu\fR
|
|
is used to become another user during a login session. Invoked without a
|
|
\fBusername\fR,
|
|
\fBsu\fR
|
|
defaults to becoming the super user. The optional argument
|
|
\fB\-\fR
|
|
may be used to provide an environment similar to what the user would expect had the user logged in directly.
|
|
.PP
|
|
Additional arguments may be provided after the username, in which case they are supplied to the user's login shell. In particular, an argument of
|
|
\fB\-c\fR
|
|
will cause the next argument to be treated as a command by most command interpreters. The command will be executed by the shell specified in
|
|
\fI/etc/passwd\fR
|
|
for the target user.
|
|
.PP
|
|
You can use the
|
|
\fB\-\-\fR
|
|
argument to separate
|
|
\fBsu\fR
|
|
options from the arguments supplied to the shell.
|
|
.PP
|
|
The user will be prompted for a password, if appropriate. Invalid passwords will produce an error message. All attempts, both valid and invalid, are logged to detect abuse of the system.
|
|
.PP
|
|
The current environment is passed to the new shell. The value of
|
|
\fB$PATH\fR
|
|
is reset to
|
|
\fI/bin:/usr/bin\fR
|
|
for normal users, or
|
|
\fI/sbin:/bin:/usr/sbin:/usr/bin\fR
|
|
for the super user. This may be changed with the
|
|
\fIENV_PATH\fR
|
|
and
|
|
\fIENV_SUPATH\fR
|
|
definitions in
|
|
\fI/etc/login.defs\fR.
|
|
.PP
|
|
A subsystem login is indicated by the presence of a "*" as the first character of the login shell. The given home directory will be used as the root of a new file system which the user is actually logged into.
|
|
.SH "OPTIONS"
|
|
.PP
|
|
The options which apply to the
|
|
\fBsu\fR
|
|
command are:
|
|
.TP 3n
|
|
\fB\-c\fR, \fB\-\-command\fR \fISHELL\fR
|
|
Specify a command that will be invoked by the shell using its
|
|
\fB\-c\fR.
|
|
.TP 3n
|
|
\fB\-\fR, \fB\-l\fR, \fB\-\-login\fR
|
|
Provide an environment similar to what the user would expect had the user logged in directly.
|
|
.sp
|
|
When
|
|
\fB\-\fR
|
|
is used, it must be specified as the last
|
|
\fBsu\fR
|
|
option. The other forms (\fB\-l\fR
|
|
and
|
|
\fB\-\-login\fR) do not have this restriction.
|
|
.TP 3n
|
|
\fB\-s\fR, \fB\-\-shell\fR \fISHELL\fR
|
|
The shell that will be invoked.
|
|
.sp
|
|
The invoked shell is choosen among (higest priority first):
|
|
.RS 3n
|
|
.TP 3n
|
|
\(bu
|
|
The shell specified with \-\-shell
|
|
.TP 3n
|
|
\(bu
|
|
If
|
|
\fB\-\-preserve\-environment\fR
|
|
is used, the shell specified by the
|
|
\fB$SHELL\fR
|
|
environment variable.
|
|
.TP 3n
|
|
\(bu
|
|
The shell indicated in the
|
|
\fI/etc/passwd\fR
|
|
entry for the target user.
|
|
.TP 3n
|
|
\(bu
|
|
|
|
\fI/bin/sh\fR
|
|
if a shell could not be found by any above method.
|
|
.RE
|
|
.IP "" 3n
|
|
.sp
|
|
If the target user has a restricted shell (i.e. the shell field of this user's entry in
|
|
\fI/etc/passwd\fR
|
|
is not specified in
|
|
\fI/etc/shell\fR), then the
|
|
\fB\-\-shell\fR
|
|
option or the
|
|
\fB$SHELL\fR
|
|
environment variable won't be taken into account unless
|
|
\fBsu\fR
|
|
is called by the root.
|
|
.TP 3n
|
|
\fB\-m\fR, \fB\-p\fR, \fB\-\-preserve\-environment\fR
|
|
Preserve the current environment.
|
|
.sp
|
|
If the target user has a restricted shell, this option has no effect (unless
|
|
\fBsu\fR
|
|
is called by root).
|
|
.SH "CAVEATS"
|
|
.PP
|
|
This version of
|
|
\fBsu\fR
|
|
has many compilation options, only some of which may be in use at any particular site.
|
|
.SH "FILES"
|
|
.TP 3n
|
|
\fI/etc/passwd\fR
|
|
User account information.
|
|
.TP 3n
|
|
\fI/etc/shadow\fR
|
|
Secure user account information.
|
|
.SH "SEE ALSO"
|
|
.PP
|
|
\fBlogin\fR(1),
|
|
\fBlogin.defs\fR(5),
|
|
\fBsh\fR(1)
|