Simple skeleton for auto-daemonizing bash script

daemon.sh

#!/bin/bash
#
# simple bash daemon skeleton
#
# Author: Luigi Pertoldi - luigi.pertoldi@hotmail.it
# Created: Mon 29 Apr 2019

usage() {
    echo >&2 "USAGE: `basename $0` [OPTIONS]"
    echo >&2 ""
    echo >&2 "  OPTIONS:"
    echo >&2 "    -v, --verbose         : enable verbose mode"
    echo >&2 "    -r, --refresh <n-sec> : set refresh interval (default 10)"
    echo >&2 "    -d, --daemon          : start indaemon mode"
    echo >&2 "    -k, --kill            : kill all running qwatch daemons"
    echo >&2 "    -h, --help            : display this help message and exit"
    exit 1;
}

refresh=10
daemon=false

options='r:u:vhkd'
longoptions='refresh:,daemon,kill,help'
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
            ;;
        -r | --refresh)
            refresh=$2
            shift 2
            ;;
        -k | --kill)
            killall -s TERM qwatch
            exit
            ;;
        -d | --daemon)
            daemon=true
            shift
            ;;
        --)
            shift
            break
            ;;
        -h | --help | *)
          usage
          ;;
    esac
done

# main loop
routine() {
    trap "echo 'INFO: quitting gracefully'; exit 1" TERM INT QUIT
    trap "echo \"daemon [pid $$] exited unexpectedly.\"; exit 1" SEGV BUS ILL HUP ABRT

    while true; do
        sleep $refresh

        # do your stuff
        # ...
    done
}

# to daemonize or not to daemonize?
if [ $daemon = true ]; then
    routine &
    disown
    echo "INFO: process started in background with pid $$"
else
    echo "INFO: starting routine, use Ctrl+C to kill."
    routine
fi