runit-scripts/functions/runit_cron

# vim: ft=sh

# env config:
#  * SLEEP: time in seconds to sleep after main action
#      default: 1080
#
#  * SERVICE: service name to be displayed as sleep argv0
#      default: "${PWD##*/}"
#
#  * STATE_FILE: path to file that indicate that main action completed
#      default: "${TMPDIR:-/tmp}/.${SERVICE}_cron"
#
# example:
#   file: /etc/sv/mlocate/run
#   ```sh
#   #!/bin/sh --
#   
#   updatedb_service() {
#     exec updatedb
#   }
#   . /etc/runit/functions/runit_cron
#   SERVICE=locate-db STATE_FILE=/run/mlocate/.state SLEEP="$(( 60 * 60 ))" \
#     runit_cron updatedb_service
#   ```
#

runit_cron() {
	set -ue

	: "${1:?}"
	: "${SERVICE:=${PWD##*/}}"
	: "${STATE_FILE:=${TMPDIR:-/tmp}/.${SERVICE}_cron}"

	if [ -f "${STATE_FILE}" ]; then
		rm -f -- "${STATE_FILE}"
		exec chpst -b "${SERVICE}: sleep" \
			sleep "${SLEEP:-$(( 30 * 60 ))}"
	else
		( umask 777 && :> "${STATE_FILE}" )
		"${@}"
	fi
}