sandebert

function substitute {
    if [ -z "$1" -o -z "$2" ]; then
        echo "Usage: substitute FROM_STRING TO_STRING [OPTION]..."
        echo
        echo "Replace all occurances of FROM_STRING (a sed-compatible regular"
        echo "expression) with TO_STRING in all files for which ack-grep matches"
        echo "FROM_STRING."
        echo
        echo "Any additional options are passed directly to ack-grep (e.g.,"
        echo " --type=html would only run the substitution on html files)."