su(1)

NAME
     su - temporarily log in as superuser or another user

SYNOPSIS
     su [name]

EXAMPLES

     su                  # Become superuser

     su ast              # Become ast

DESCRIPTION

     Su can be used to temporarily login as another user.  It prompts for  the
     superuser  password.   If  the  correct password is entered, su creates a
     shell with the desired uid.  If no name is specified,  root  is  assumed.
     To  exit  the  temporary shell, type CTRL-D.  When memory is tight, it is
     better to become superuser by logging out and then logging  in  again  as
     root,  rather  than  using  su since the latter creates an extra shell in
     memory.  Any user with a zero group id need not type  a  password.   This
     makes life easier for the system administrator.

SEE ALSO
     login(1).