common shell functions, a skeleton for new scripts

building-blocks.sh

SELF=${0##*/}

die() {
    log "$@"
    exit 1
}

log() {
    printf "$SELF: %s\n" "$@" >&2
}

usage() {
    cat <<EOF
usage: $self [--help]

Examples:

  $SELF --help

EOF
}

requireCommand() {
    command -v $1 >/dev/null 2>&1 || die "'$1' is required, but not found"
}

while [ $# -gt 0 ]; do
    case "$1" in
        "")
            usage
            die "unrecognized argument: $1"
            exit 1
            ;;
        --help|help|-help|-h)
            usage
            exit 0
            ;;
        somearg|-a)
            shift
            ;;
        *)
            die "unrecognized argument: $1"
            ;;
    esac
done