/etc/crontabに記載した各ジョブの終了時間をログに残す

vim ~/cronlog.sh 
---
#!/bin/sh
logfile="/root/cron.log"
touch /root/cron.log
chmod 0777 /root/cron.log

buf=""
while read f; do
  line=$f

  if [ -n "$line" ] && [ `echo "$line" | egrep "^ *([0-9]|\*)" | wc -l` -gt 0 ] ;then
    line="${line};echo \"${line} - \`date\`\" >> ${logfile}"
  fi

  buf=`cat <<EOM
$buf
$line
EOM`
done

echo "$buf"
---

chmod +x ~/cronlog.sh 
cat /etc/crontab | ~/cronlog.sh 1> /etc/crontab.debug
mv /etc/crontab{,.bak}; cp /etc/crontab{.debug,} 

cp /etc/crontab{,.debug}