    Set export attribute for shell variables.
    
    Marks each NAME for automatic export to the environment of subsequently
    executed commands.  If VALUE is supplied, assign VALUE before exporting.
    
    Options:
      -f	refer to shell functions
      -n	remove the export property from each NAME
      -p	display a list of all exported variables and functions
    
    An argument of `--' disables further option processing.
    
    Exit Status:
    Returns success unless an invalid option is given or NAME is invalid.
