#!/bin/bash
echo "Shell Build-in Variables"
echo ""
echo $#
echo "#	    the number of arguments"
echo "------------------------------------"
echo $*
echo "*	    all arguments to shell"
echo "------------------------------------"
echo $-
echo "-		options supplied to the shell"
echo "------------------------------------"
echo $?
echo "?		return value of the last command executed"
echo "------------------------------------"
echo $$
echo "$		process-id of the shell"
echo "------------------------------------"
echo $!
echo "!		process-id of the last command started with &"
echo "------------------------------------"
echo $HOME
echo "HOME	default argument of cd command"
echo "------------------------------------"
echo $IFS
echo "IFS	list of characters that separate words in arguments"
echo "------------------------------------"
echo $MAIL
echo "MAIL	file that, when changed, triggers you have mail message"
echo "------------------------------------"
echo $PATH
echo "PATH	list of directories to search for commands"
echo "------------------------------------"
echo $PS1
echo "PS1	promopt string, default is '$'"
echo "------------------------------------"
echo $PS2
echo "PS2	promopt string for continued command line, default '>'"