Simple getopt example for bash

getopt.cc

#include <getopt.h>
#include <iostream>
#include <string>
#include <vector>

int main(int argc, char** argv) {

    std::string progname(argv[0]);

    auto usage = [&]() {
        std::cerr << "USAGE: " << progname << " [-v|--verbose] [-h|--help] [--p0 <val> (default 0.01)] file1 file2 ...\n";
    };

    const char* const short_opts = ":vh";
    const option long_opts[] = {
        { "p0",      required_argument, nullptr, 1   },
        { "verbose", no_argument,       nullptr, 'v' },
        { "help",    no_argument,       nullptr, 'h' },
        { nullptr,   no_argument,       nullptr, 0   }
    };

    // default p0 value
    double p0 = 0.01;

    int opt = 0;
    while ((opt = getopt_long(argc, argv, short_opts, long_opts, nullptr)) != -1) {
        switch (opt) {
            case 1:
                p0 = std::stod(optarg);
            case 'v':
                level = debug;
                break;
            case 'h': // -h or --help
            case '?': // Unrecognized option
            default:
                usage();
                return 1;
        }
    }

    // extra arguments
    std::vector<std::string> args;
    for(; optind < argc; optind++){
        args.emplace_back(argv[optind]);
    }

    if (args.empty()) {usage(); return 1;}
 
    return 0;
}

getopt.sh

#!/usr/bin/env bash

usage() { echo "USAGE: `basename $0` [-v] --config file.json --destdir /path/to/gerda-pdfs -- dir_with_raw" 1>&2; exit 1;}

options='vh'
longoptions='config:,destdir:'
parsed=$(getopt --name `basename $0` --options $options --longoptions $longoptions -- "$@")
[ $? -eq 0 ] || exit 1
eval set -- "$parsed"
while true; do
    case "$1" in
        -v)
            set -xv
            shift
            ;;
        --config)
            config=$2
            shift 2
            ;;
        --destdir)
            destdir=$2
            shift 2
            ;;
        --)
            shift
            break
            ;;
        -h | *)
          usage
          ;;
    esac
done

# get args after all options
argument=$1

# check mandatory options/arguments
[ -z "$config" ] && usage
[ -z "$destdir" ] && usage