SU(U)                                                       SU(U)



NAME
       su - Change user ID or become super-user

SYNOPSIS
       su [OPTS] [-] [username [ARGS]]

DESCRIPTION
       su  is used to become another user during a login session.
       Invoked without a username, su defaults  to  becoming  the
       super  user.   The optional argument - may be used to pro-
       vide an environment similiar to what the user would expect
       had the user logged in directly.

       The  user will be prompted for a password, if appropriate.
       Invalid passwords will  produce  an  error  message.   All
       attempts,  both  valid  and  invalid, are logged to detect
       abuses of the system.

       An optional command can be executed. This is done  by  the
       shell  specified in /etc/passwd for the target user unless
       the -s or -m options are  used.   Any  arguments  supplied
       after  the  username  will  be passed to the invoked shell
       (shell must support the -c command line  option  in  order
       for a command to be passed to it).

       The  current  environment is passed to the new shell.  The
       value of $PATH is reset to /bin:/usr/bin for normal users,
       or /sbin:/bin:/usr/sbin:/usr/bin for the super user.  This
       may be changed with the ENV_PATH  and  ENV_SUPATH  defini-
       tions in /etc/login.defs. When using the -m or -p options,
       the users environment is not changed.

       A subsystem login is indicated by the presense of a "*" as
       the  first  character  of  the login shell. The given home
       directory will be used as the root  of  a  new  filesystem
       which the user is actually logged into.

OPTIONS
       -      make this a login shell

       -c, --commmand=<command>
              pass  command  to  the  invoked  shell using its -c
              option

       -m, -p, --preserve-environment
              do not reset environment variables,  and  keep  the
              same shell

       -s, --shell=<shell>
              use shell instead of the default in /etc/passwd


NOTES
       The  -m,  -p  and  -s options are restricted by the target
       user's shell being listed  in  /etc/shells.  If  it's  not
       listed,  then  it's  assumed to be a restricted account, a
       normal su is performed,  and  those  options  are  ignored
       silently.

       A subsystem login is indicated by the presense of a "*" as
       the first character of the login  shell.  The  given  home
       directory  will  be  used  as the root of a new filesystem
       which the user is actually logged into.

CAVEATS
       This version of su has many compilation options, only some
       of which may be in use at any particular site.

Files
       /etc/passwd - user account information
       /etc/shadow - encrypted passwords and age information
       /etc/shells - valid user shells
       $HOME/.profile - initialization script for default shell

SEE ALSO
       login(n), sh(h), login.defs(s), shells(s)

AUTHOR
       Julianne Frances Haugh (jfh@austin.ibm.com)



                                                            SU(U)