su(1)                                                       su(1)



NAME
     su - substitutes user ID

SYNOPSIS
     su [-] [name[arg ...]]

ARGUMENTS
     -      Changes your environment to that of name for the
            temporary login session.

     arg    Specifies the information that is passed to the
            program invoked as the shell.  When using programs
            like sh(1), an arg of the form -c string executes
            string via the shell and an argument of -r will give
            the user a restricted shell.

     name   Specifies the name of the user you wish to assume.

DESCRIPTION
     su allows a user to become another user without logging off.
     The default user name is root (that is, superuser).

     To use su, the appropriate password must be supplied (unless
     one is already root).  If the password is correct, su will
     execute a new shell with the real and effective user ID set
     to that of the specified user.  The new shell will be the
     optional program named in the shell field of the specified
     user's password file entry (see passwd(4)), or /bin/sh if
     none is specified (see sh(1)).  To restore normal user ID
     privileges, type an EOF (CONTROL-D) to the new shell.

     The following statements are true only if the optional
     program named in the shell field of the specified user's
     password file entry is like sh(1).  If the first argument to
     su is a -, the environment will be changed to what would be
     expected if the user actually logged in as the specified
     user.  This is done by invoking the program used as the
     shell with an arg0 value whose first character is -, thus
     causing the system's profile (/etc/profile) and then the
     specified user's profile (.profile in the new HOME
     directory) to be executed.  Otherwise, the environment is
     passed along with the possible exception of $PATH, which is
     set to /bin:/etc:/usr/bin:/usr/etc for root.

     Note that if the optional program used as the shell is
     /bin/sh, the user's .profile can check arg0 for -sh or -su
     to determine if it was invoked by login(1) or su(1),
     respectively.  If the user's program is other than /bin/sh,
     then the program is invoked with an arg0 of -program by both
     login(1) and su(1).





January 1992                                                    1

su(1)                                                       su(1)



     All attempts to become another user using su are logged in
     the log file /usr/adm/sulog.

EXAMPLES
     The command

        su joshua

     would cause the system to prompt for joshua's password; if
     the password is typed in correctly, joshua's identity is
     substituted.

     To become user justin while retaining the previously
     exported environment, execute

        su justin

     To become user justin but change the environment to what
     would be expected if justin had originally logged in,
     execute

        su - justin

     To execute command with the temporary environment and
     permission of user justin, type

        su - justin -c "command args"


FILES
     /bin/su
          Executable file
     /etc/passwd
          Password file
     /etc/profile
          Profile file
     $HOME.profile
          Home directory profile file
     /usr/adm/sulog
          Log of substitute users

SEE ALSO
     csh(1), env(1), ksh(1), login(1), sh(1)

     passwd(4), profile(4), environ(5) in Πm










2                                                    January 1992