Enable and disable cron jobs in a file by commenting/uncommenting them.

manage-cron-jobs.sh

#!/usr/bin/env bash

function usage () {
	cat <<EOF
Usage: $0 [-p] -e|-d -f <file>
where:
    -e enable cron jobs
    -d disable cron jobs
    -p print only
    -f modify existing file
    -h show help
EOF
}

sed_opts='-i'
while getopts 'edf:hp' flag; do
	case "${flag}" in
		e)
			sed_regex='/^#[ ]*\([\*0-9/]\+ \)\{5\}.*$/s/^#[ ]*//'
			action='enable'
			;;
		d)
			sed_regex='/^\([\*0-9/]\+ \)\{5\}.*$/s/^/#/'
			action='disable'
			;;
		f)
			file=${OPTARG};;
		p)
			print_only=true
			sed_opts=''
			;;
		h)
			echo "Enable/disable cron jobs by commenting/uncommenting them."
			usage
			exit 0
			;;
	esac
done

if [ -z "${file}" ] ; then
	echo "Error: no file specified."
	usage
	exit 1
elif [ ! -f "${file}" ] ; then
	echo "Error: specified file ${file} does not exist."
	usage
	exit 1
elif [ -z "${action}" ] ; then
	echo "Error: no action specified."
	usage
	exit 1
fi

if [ -n "${print_only}" ] ; then
	echo "Printing output only."
fi

sed ${sed_opts} "${sed_regex}" "${file}" && echo "Cron jobs in ${file} ${action}d.";