bash scripting helpers -- command line argument parsing, and some logging functions

gistfile1.sh

function usage() {
    cat <<EOD
$0 [-hnv]
    -h, --help     Print this text and exit
    -n, --dry-run  Dryrun; do not make any changes
    -v, --verbose  Enable verbose output; repeat for more verbosity
EOD
}

function debug() {
    [ $DEBUG != 0 ] && echo $*
}

function info() {
    echo $*
}

function warn() {
    echo $* 2>&1
}

function fatal() {
    warn $*
    exit 1
}

DEBUG=0
DRYRUN=0

while [[ $# > 0 ]]; do
    case $1 in
        -v|--verbose)
            if [ $DEBUG == 0 ]; then
                DEBUG=1;
            elif [ $DEBUG == 1 ]; then
                DEBUG=2
                set -v
            else
                DEBUG=3
                set -x
            fi
            ;;
        -n|--dry-run)
            DRYRUN=1
            ;;
        -h|--help)
            usage
            exit 0
            ;;
        *)
            warn Unknown flag $1
            usage
            exit 1
            ;;
    esac
    shift
done

[ $DRYRUN != 0 ] && warn "DRYRUN - no changes will be made"