.\" Copyright (c) 2003 - 2006 Kungliga Tekniska Högskolan .\" (Royal Institute of Technology, Stockholm, Sweden). .\" All rights reserved. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" .\" 3. Neither the name of the Institute nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``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. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" $Id$ .\" .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