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SU(1)                     BSD General Commands Manual                    SU(1)

NAME
     su -- substitute user identity

SYNOPSIS
     su [-] [-flm] [login [args]]

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 appro-priate appropriate
     priate user ID is executed.

     The options are as follows:

     -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 environment.  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'' (normally 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