$ sort --version
sort (GNU coreutils) 5.97
Copyright (C) 2006 Free Software Foundation, Inc.
This is free software.  You may redistribute copies of it under the terms of
the GNU General Public License <http://www.gnu.org/licenses/gpl.html>.
There is NO WARRANTY, to the extent permitted by law.

Written by Mike Haertel and Paul Eggert.

$ dir
sh: dir: command not found

$ path
sh: path: command not found

$ set path

$ echo path
path

$ echo $path

$ exit