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aaronNGi/newscript.sh

Created April 28, 2020 20:38
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  1. aaronNGi created this gist Apr 28, 2020.
    113 changes: 113 additions & 0 deletions newscript.sh
    View file
    Original file line number Diff line number Diff line change
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    #!/bin/sh

    prog_name=${0##*/}
    version=1.0
    version_text="Boilerplate for new scripts v$version"
    options="h o: q v V"
    help_text="Usage: $prog_name [-o <text>] [-hqvV] [<file>]...
    Boilerplate for new scripts
    -o <text> Set an option with a parameter
    -h Display this help text and exit
    -q Quiet
    -v Verbose mode
    -V Display version information and exit"

    main() {
    set_defaults
    parse_options "$@"
    shift $((OPTIND-1))
    # If we want to use `getopts` again, this has to be set to 1.
    OPTIND=1

    # shellcheck disable=2154
    {
    $option_h && usage
    $option_V && version
    $option_q && info() { :; }
    $option_o && info "option 'o' has parameter '$param_o'"
    $option_v && info "verbose mode is on"
    }

    _i=1
    for _file do
    info "operand $_i is '$_file'"
    _i=$((_i+1))
    done
    unset _i _file

    [ -t 0 ] ||
    info "stdin is not a terminal"
    }

    ##########################################################################

    # shellcheck disable=2034,2046
    set_defaults() {
    set -e
    trap 'clean_exit' EXIT TERM
    trap 'clean_exit HUP' HUP
    trap 'clean_exit INT' INT
    IFS=' '
    set -- $(printf '\n \r \t \033')
    nl=$1 cr=$2 tab=$3 esc=$4
    IFS=\ $tab
    }

    # For a given optstring, this function sets the variables
    # "option_<optchar>" to true/false and param_<optchar> to its parameter.
    parse_options() {
    for _opt in $options; do
    # The POSIX spec does not say anything about spaces in the
    # optstring, so lets get rid of them.
    _optstring=$_optstring$_opt
    eval "option_${_opt%:}=false"
    done

    while getopts ":$_optstring" _opt; do
    case $_opt in
    :) usage "option '$OPTARG' requires a parameter" ;;
    \?) usage "unrecognized option '$OPTARG'" ;;
    *)
    eval "option_$_opt=true"
    [ -n "$OPTARG" ] &&
    eval "param_$_opt=\$OPTARG"
    ;;
    esac
    done
    unset _opt _optstring OPTARG
    }

    info() { printf %s\\n "$*" >&2; }
    version() { printf %s\\n "$version_text"; exit; }

    error() {
    _error=${1:-1}
    shift
    printf '%s: Error: %s\n' "$prog_name" "$*" >&2
    exit "$_error"
    }

    usage() {
    [ $# -ne 0 ] && {
    exec >&2
    printf '%s: %s\n\n' "$prog_name" "$*"
    }
    printf %s\\n "$help_text"
    exit ${1:+1}
    }

    clean_exit() {
    _exit_status=$?
    trap - EXIT
    info "exiting"

    [ $# -ne 0 ] && {
    trap - "$1"
    kill -s "$1" -$$
    }
    exit "$_exit_status"
    }

    main "$@"