better version with non-racy locking

run-crons (text/plain), 2.51 KB, created by Aron Griffis (RETIRED) on 2004-05-06 15:25:31 UTC

#!/bin/bash
#
# $Header: /home/cvsroot/gentoo-x86/sys-apps/cronbase/files/run-crons,v 1.9 2003/11/19 06:31:23 prez Exp $
#
#
# 06 May 2004; Aron Griffis <[e-mail]> run-crons:
#     make the locking actually work.  The old code was racy
#
# 23 Jun 2002; Jon Nelson <[e-mail]> run-crons:
#     fixed a race condition, where cron jobs and run-crons wanted to
#     delete touch files
#
# 20 Apr 2002; Thilo Bangert <[e-mail]> run-crons:
#     moved lastrun directory to /var/spool/cron/lastrun
#
# Author: Achim Gottinger <[e-mail]>
#
# Mostly copied from SuSE
#
# this script looks into /etc/cron.[hourly|daily|weekly|monthly]
# for scripts to be executed. The info about last run is stored in
# /var/spool/cron/lastrun

LOCKDIR=/var/spool/cron/lastrun
LOCKFILE=${LOCKDIR}/lock

mkdir -p ${LOCKDIR}

# Make sure we're not running multiple instances at once.
# Try twice to lock, otherwise give up.
for ((i = 0; i -lt 2; i = i + 1)); do
    ln -sn $$ ${LOCKFILE} 2>/dev/null
    if [[ $? != 0 ]]; then
        # lock failed, check for a running process.
        # handle both old- and new-style locking.
        cronpid=$(readlink ${LOCKFILE} 2>/dev/null ||
                  cat ${LOCKFILE} 2>/dev/null)
        if [[ $? == 0 ]]; then 
            if kill -0 ${cronpid} 2>/dev/null; then
                # whoa, another process is really running
                exit 0
            else
                rm -f ${LOCKFILE}
            fi
        fi
    fi
done

# Set a trap to remove the lockfile when we're finished
trap "rm -f ${LOCKFILE}" 0 1 2 3 15


for BASE in hourly daily weekly monthly
do
    CRONDIR=/etc/cron.${BASE}

    test -d $CRONDIR || continue

    if [ -e ${LOCKDIR}/cron.$BASE ]
    then
	case $BASE in
	    hourly)
		#>= 1 hour, 5 min -=> +65 min
		TIME="-cmin +65" ;;
	    daily)
		#>= 1 day, 5 min -=> +1445 min
		TIME="-cmin +1445"  ;;
	    weekly)
		#>= 1 week, 5 min -=> +10085 min
		TIME="-cmin +10085"  ;;
	    monthly)
		#>= 31 days, 5 min -=> +44645 min
		TIME="-cmin +44645" ;;
	esac
        find ${LOCKDIR} -name cron.$BASE $TIME -exec rm {} \;
    fi

    # if there is no touch file, make one then run the scripts
    if [ ! -e ${LOCKDIR}/cron.$BASE ]
    then
        touch ${LOCKDIR}/cron.$BASE

        set +e
        for SCRIPT in $CRONDIR/*
        do
            if [[ -x $SCRIPT && ! -d $SCRIPT ]]; then
                $SCRIPT
            fi
        done
    fi
done

# Clean out bogus cron.$BASE files with future times
touch ${LOCKDIR}
find ${LOCKDIR} -newer ${LOCKDIR} -exec /bin/rm -f {} \;