.\" Copyright (c) 1988, 1990, 1993, 1994 .\" The Regents of the University of California. 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. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University 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 REGENTS 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 REGENTS 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. .\" .\" from: @(#)su.1 8.2 (Berkeley) 4/18/94 .\" $NetBSD: su.1,v 1.14 1997/10/19 23:31:52 lukem Exp $ .\" .Dd April 18, 1994 .Dt SU 1 .Os .Sh NAME .Nm su .Nd substitute user identity .Sh SYNOPSIS .Nm .Op Fl Kflm .Op Ar login Op Ar "shell arguments" .Sh DESCRIPTION .Nm requests the Kerberos password for .Ar login (or for .Dq Ar login Ns .root , if no login is provided), and switches to that user and group ID after obtaining a Kerberos ticket granting ticket. A shell is then executed, and any additional .Ar "shell arguments" after the login name are passed to the shell. .Nm will resort to the local password file to find the password for .Ar login if there is a Kerberos error. If .Nm is executed by root, no password is requested and a shell with the appropriate user ID is executed; no additional Kerberos tickets are obtained. .Pp Alternatively, if the user enters the password "s/key", authentication will use the S/Key one-time password system as described in .Xr skey 1 . S/Key is a Trademark of Bellcore. .Pp By default, the environment is unmodified with the exception of .Ev USER , .Ev HOME , and .Ev SHELL . .Ev HOME and .Ev SHELL are set to the target login's default values. .Ev USER is set to the target login, unless the target login has a user ID of 0, in which case it is unmodified. The invoked shell is the target login's. This is the traditional behavior of .Nm su . .Pp The options are as follows: .Bl -tag -width Ds .It Fl K Do not attempt to use Kerberos to authenticate the user. .It Fl f If the invoked shell is .Xr csh 1 , this option prevents it from reading the .Dq Pa .cshrc file. .It Fl l Simulate a full login. The environment is discarded except for .Ev HOME , .Ev SHELL , .Ev PATH , .Ev TERM , and .Ev USER . .Ev HOME and .Ev SHELL are modified as above. .Ev USER is set to the target login. .Ev PATH is set to .Dq Pa /bin:/usr/bin . .Ev TERM is imported from your current environment. The invoked shell is the target login's, and .Nm will change directory to the target login's home directory. .It Fl m Leave the environment unmodified. The invoked shell is your login shell, and no directory changes are made. As a security precaution, if the target user's shell is a non-standard shell (as defined by .Xr getusershell 3 ) and the caller's real uid is non-zero, .Nm will fail. .El .Pp The .Fl l and .Fl m options are mutually exclusive; the last one specified overrides any previous ones. .Pp Only users in group .Dq wheel (normally gid 0), as listed in .Pa /etc/group , can .Nm to .Dq root . .Pp By default (unless the prompt is reset by a startup file) the super-user prompt is set to .Dq Sy \&# to remind one of its awesome power. .Sh SEE ALSO .Xr csh 1 , .Xr login 1 , .Xr sh 1 , .Xr skey 1 , .Xr kinit 1 , .Xr kerberos 1 , .Xr passwd 5 , .Xr group 5 , .Xr environ 7 .Sh ENVIRONMENT Environment variables used by .Nm : .Bl -tag -width "HOME" .It Ev HOME Default home directory of real user ID unless modified as specified above. .It Ev PATH Default search path of real user ID unless modified as specified above. .It Ev TERM Provides terminal type which may be retained for the substituted user ID. .It Ev USER The user ID is always the effective ID (the target user ID) after an .Nm unless the user ID is 0 (root). .El .Sh HISTORY A .Nm command appeared in .At v7 .