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SU(1V)                                                                  SU(1V)

       su - super-user, temporarily switch to a new user ID

       su [ - ] [ -f ] [ username [ arg...  ] ]

       su [ - ] [ username [ arg...  ] ]

       The  System  V  version  of this command is available with the System V
       software installation option.  Refer  to  for  information  on  how  to
       install optional software.

       su  creates  a new shell process that has the user ID for the specified
       username as its real and effective user ID.  su asks for the  password,
       just  as  if  you  were logging in as username, and, if the password is
       given, changes the real and effective user IDs and group IDs and  group
       set  to  those of username and invokes the shell specified in the pass-
       word file for that username, without changing  the  current  directory.
       The user environment is thus unchanged except for HOME and SHELL, which
       are taken from the password file for the user  being  substituted  (see
       environ(5V)).   If  username  is not root, USER is changed to username.
       The new user ID stays in force until the shell exits.

       The new shell will not be a login shell, so it will not read username's
       .login  or  .profile  files,  but  it will read any other configuration
       files for that user (for instance, the .cshrc file  for  the  C  shell)
       just as if that user had invoked a new shell.

       If  no  username  is  specified,  root  is assumed.  If the wheel group
       (group 0) does not contain a null user list and has members, only  they
       can  su to root, even with the root password.  To remind the super-user
       of his responsibilities, the shell substitutes `#' for '$'  or  '%'  in
       its  usual prompt (except if you will be running sh(1) and PS1 is set -
       in this case, the prompt will not be modified).   If  args  are  given,
       they are passed to username's shell.

       Any  additional  arguments  given on the command line are passed to the
       program invoked as the shell.   When  using  programs  like  sh(1)  and
       csh(1), an arg of the form -c string executes string via the shell.

       -              Perform a complete login.  Remove all variables from the
                      environment except for TERM, set USER to  username,  set
                      HOME   and   SHELL  as  specified  above,  set  PATH  to
                      :/usr/ucb:/bin:/usr/bin,  change  directories  to  user-
                      name's  home directory, and tell the shell to read user-
                      name's .login or .profile file.

       -f             Perform a fast su by passing the -f flag to  the  shell.
                      This  flag  is  only  meant for use with the C shell; it
                      will prevent the C shell from reading username's  .cshrc
                      file.  If it is used with the Bourne shell, it will dis-
                      able filename generation.


       csh(1), login(1), sh(1), environ(5V)

       su does not accept 8-bit user IDs.  See login(1) for explanations about
       why 8-bit login names are not acceptable.

       su  fails when run from within a subdirectory of a directory that user-
       name either cannot search, or cannot read (that is, username  does  not
       have both read and execute permission).

       su  fails  to reset the user ID to root when the current working direc-
       tory is in an NFS-mounted file system, and does  not  have  its  search
       permission set for "other" users.

                               21 September 1989                        SU(1V)