.TH su "" "" Command
.PC "Substitute user id, become superuser"
\fBsu [\fIuser \fB[\fIcommand\^\fB] ]\fR
.PP
Default \fIuser\fR is \fBroot\fR; default \fIcommand\fR is \fBsh\fR.
.HE
.B su
changes the real user id and the effective user id to that of the
.IR user .
If
.I user
has a login password,
.B su
requests it.
Then it executes the specified
.IR command .
.PP
If
.I command
is absent,
.B su
invokes an interactive sub-shell.
.PP
If
.I user
is absent,
.B su
assumes user name
.B root
(the superuser).
.SH Files
\fB/etc/passwd\fR \(em Login names and passwords
.SH "See Also"
.Xr "commands," commands
.Xr "login," login
.Xr "newgrp," newgrp
.Xr "sh," sh
.Xr "superuser" superuser
