       . file [ arg ... ]
              Read commands from file and  execute  them  in  the
              current  shell  environment.  If file does not con-
              tain a slash, or if PATH DIRS  is  set,  the  shell
              looks  in the components of path to find the direc-
              tory containing file.  Files in the current  direc-
              tory  are  not read unless "." appears somewhere in
              path.  If any arguments arg are given, they  become
              the   positional  parameters;  the  old  positional
              parameters are restored when the file is done  exe-
              cuting.   The exit status is the exit status of the
              last command executed.

       source Same  as  .,  except  that the current directory is
              always  searched  and  is  always  searched  first,
              before directories in path.
