Name Description

HOME this is the pathname of your "home"

   directory when you login and to which
   cd changes when invoked with no argument.

PATH defines the directories searched when

   the shell is looking for the  file to
   execute when processing a command.

MAIL if set to the name of a mail file the

   shell will inform you of the arrival
   of new mail.

PS1 contains the shell prompt string.

PS2 is the continuation prompt when a command

   spans more than one line.

IFS (Internal Field Separator) The set of

   characters used for blank interpretation
   in the shell.  Normally space, TAB and newline.