SU(1)                   System General Commands Manual                   SU(1)

NAME
     su - substitute user identity

SYNOPSIS
     su [-flm] [login] [-c shell arguments]

DESCRIPTION
     su requests the password for login and switches to that user and group ID
     after obtaining proper authentication.  A shell is then executed, and any
     additional shell arguments after the login name are passed to the shell.
     If su is executed by root, no password is requested and a shell with the
     appropriate user ID is executed.

     The options are as follows:

     -c      Invoke the following command in a subshell as the specified user.

     -f      If the invoked shell is csh(1), this option prevents it from
             reading the ``.cshrc'' file.

     -l      Simulate a full login.  The environment is discarded except for
             HOME, SHELL, PATH, TERM, and USER.  HOME and SHELL are modified
             as above.  USER is set to the target login.  PATH is set to
             ``/bin:/usr/bin''.  TERM is imported from your current environ-
             ment.  The invoked shell is the target login's, and su will
             change directory to the target login's home directory.  This
             option is identical to just passing "-", as in "su -".

     -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 getusershell(3)) and the caller's real uid is non-
             zero, su will fail.

     The -l and -m options are mutually exclusive; the last one specified
     overrides any previous ones.

     Only users in group ``wheel'' (normally gid 0) or group ``admin'' (nor-
     mally gid 20) can su to ``root''.

     By default (unless the prompt is reset by a startup file) the super-user
     prompt is set to ``#'' to remind one of its awesome power.

SEE ALSO
     csh(1), login(1), sh(1), skey(1), kinit(1), kerberos(1), passwd(5),
     group(5), environ(7)

ENVIRONMENT
     Environment variables used by su :

     HOME  Default home directory of real user ID unless modified as specified
           above.

     PATH  Default search path of real user ID unless modified as specified
           above.

     TERM  Provides terminal type which may be retained for the substituted
           user ID.

     USER  The user ID is always the effective ID (the target user ID) after
           an su unless the user ID is 0 (root).

HISTORY
     A su command appeared in Version 7 AT&T UNIX.

BSD                             April 18, 1994                             BSD