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.\" $Id$
.\"
.Dd January 12, 2006
.Dt SU 1
.Os HEIMDAL
.Sh NAME
.Nm su
.Nd substitute user identity
.Sh SYNOPSIS
.Nm su
.Op Fl K | Fl Fl no-kerberos
.Op Fl f
.Op Fl l | Fl Fl full
.Op Fl m
.Oo Fl i Ar instance \*(Ba Xo
.Fl Fl instance= Ns Ar instance
.Xc
.Oc
.Oo Fl c Ar command \*(Ba Xo
.Fl Fl command= Ns Ar command
.Xc
.Oc
.Op Ar login Op Ar "shell arguments"
.Sh DESCRIPTION
.Nm su
will use Kerberos authentication provided that an instance for the
user wanting to change effective UID is present in a file named
.Pa .k5login
in the target user id's home directory
.Pp
A special case exists where
.Ql root Ap s
.Pa ~/.k5login
needs to contain an entry for:
.Ql user Ns / Ns Ao instance Ac Ns @ Ns REALM
for
.Nm su
to succed (where
.Aq instance
is
.Ql root
unless changed with
.Fl i ) .
.Pp
In the absence of either an entry for current user in said file or
other problems like missing
.Ql host/hostname@REALM
keys in the system's
keytab, or user typing the wrong password,
.Nm su
will fall back to traditional
.Pa /etc/passwd
authentication.
.Pp
When using
.Pa /etc/passwd
authentication,
.Nm su
allows
.Ql root
access only to members of the group
.Ql wheel ,
or to any user (with knowledge of the
.Ql root
password) if that group
does not exist, or has no members.
.Pp
The options are as follows:
.Bl -item -width Ds
.It
.Fl K ,
.Fl Fl no-kerberos
don't use Kerberos.
.It
.Fl f
don't read .cshrc.
.It
.Fl l ,
.Fl Fl full
simulate full login.
.It
.Fl m
leave environment unmodified.
.It
.Fl i Ar instance ,
.Fl Fl instance= Ns Ar instance
root instance to use.
.It
.Fl c Ar command ,
.Fl Fl command= Ns Ar command
command to execute.
.El