Bash Shell Script Template

template.sh

#!/bin/bash
# Bash script template
#
# Copyright 2017 Canonical Ltd.
# Joshua Powers <josh.powers@canonical.com>

VERBOSITY=0
TEMP_D=""

error() { echo "$@" 1>&2; }
fail() { [ $# -eq 0 ] || error "$@"; exit 1; }
bad_usage() { usage 1>&2; [ $# -eq 0 ] || error "$@"; return 1; }

cleanup() {
    [ -z "${TEMP_D}" ] || [ ! -d "${TEMP_D}" ] || rm -Rf "${TEMP_D}"
}

debug() {
    local level=${1}; shift;
    [ "${level}" -gt "${VERBOSITY}" ] && return
    error "${@}"
}

usage() {
    cat <<EOF
Usage: ${0##*/} [ options ] <<ARGUMENTS>>

   <<SUMMARY HERE>>

   options:
      <<OPTIONS HERE>>
EOF
}

main() {
    local short_opts="ho:v"
    local long_opts="help,output:,verbose"
    local getopt_out=""
    getopt_out=$(getopt --name "${0##*/}" \
        --options "${short_opts}" --long "${long_opts}" -- "$@") ||
        { bad_usage; return; }
    eval set -- "${getopt_out}" ||
        { bad_usage; return; }

    ## <<insert default variables here>>
    local output=""

    local cur="" next=""
    while [ $# -ne 0 ]; do
        cur="$1"; next="$2";
        case "$cur" in
            -h|--help) usage ; exit 0;;
            -o|--output) output=$next; shift;;
            -v|--verbose) VERBOSITY=$((VERBOSITY+1));;
            --) shift; break;;
        esac
        shift;
    done

    ## check arguments here - how many args do you expect?
    #[ $# -lt 3 ] && { bad_usage "must provide 3 args"; return; }
    [ $# -ne 1 ] || { bad_usage "must provide arguments"; return; }

    TEMP_D=$(mktemp -d "${TMPDIR:-/tmp}/${0##*/}.XXXXXX") ||
        fail "failed to make tempdir"
    trap cleanup EXIT

    # program starts here
    echo "Hello World."
    echo "$output"
    i=0; for x in "$@"; do i=$((i+1)); echo "arg[$i]:$x"; done
    return 0
}

main "$@"
# vi: ts=4 noexpandtab