Useful bash funcs

shared-funcs.sh

# Shell Scripting Functions so that scripting is less sad
# not an executable script -- source me in other scripts!

# always start unset
unset abort_message
# start with default of 0
rc=0
# Abort with message
function abort () {
    echo "$abort_message" >&2
    exit $rc
}
# Check if abort is necessary, and if so do it
function check_rc () {
    if [ $# -gt 0 ];
    then
        abort_message="$1"
    fi

    if [ $rc -ne 0 ];
    then
        abort
    fi
}
# Check if abort is necessary, fetching rc first
function check_last_rc () {
    # must be the first command of the function
    rc=$?
    check_rc "$@"
}

# always start unset
unset usage_message
# Send usage output, but don't necessarily exit
function usage () {
    echo "USAGE: $usage_message" >&2
}
# Send usage error message and exit
function usage_error () {
    abort_message="USAGE ERROR: $usage_message"
    rc=2
    abort
}

# checks for the '-h' option when no other options are allowed
# requires arguments of the form "<USAGE> $@"
function check_help_opt () {
    usage_message="$1"
    local OPTIND
    shift 1

    while getopts "h" option;
    do
        case "$option" in
            h)
                usage
                exit 0
                ;;
        esac
    done
}