(features.info)Bourne Shell Variables

Bourne Shell Variables
======================

   Bash uses certain shell variables in the same way as the Bourne
shell.  In some cases, Bash assigns a default value to the variable.

`IFS'
     A list of characters that separate fields; used when the shell
     splits words as part of expansion.

`PATH'
     A colon-separated list of directories in which the shell looks for
     commands.

`HOME'
     The current user's home directory.

`CDPATH'
     A colon-separated list of directories used as a search path for
     the `cd' command.

`MAILPATH'
     A colon-separated list of files which the shell periodically checks
     for new mail.    You can also specify what message is printed by
     separating the file name from the message with a `?'.  When used
     in the text of the message, `$_' stands for the name of the
     current mailfile.

`PS1'
     The primary prompt string.

`PS2'
     The secondary prompt string.

`OPTIND'
     The index of the last option processed by the `getopts' builtin.

`OPTARG'
     The value of the last option argument processed by the `getopts'
     builtin.