Debugging shell scripts

To get debugging info without modifying the script:

$ bash -x script.sh

To put debugging code within a script:

set -x : Display commands as they are executed
set -v : Display shell input lines as they are read

I like to trigger these via getopts and a case statement:

while getopts ":vh" opt; do
        case $opt in
		v )
                        set -x
			set -v
                ;;
		h )
			echo "$HelpPage"
		;;
	esac

See this good UnixCraft article. 04/24/2009