How to efficiently back up and restore crontab
Tags:
Oracle,
Technical Track
When a database environment is being patched, entries from crontab are commented and then removed when patching is completed. The process works well when there are only a few entries from crontab, but it does not scale when crontab has dozens of entries and when some entries are commented and some are not. I believe a more efficient method is to backup and restore the existing crontab. Here's a demo: Crontab entries.
[oracle@racnode-dc1-1 ~]$ crontab -l */05 * * * * /bin/date > /tmp/date.out 2>&1 */15 * * * * /bin/date > /tmp/date.out 2>&1 #*/25 * * * * /bin/date > /tmp/date.out 2>&1 */35 * * * * /bin/date > /tmp/date.out 2>&1 */45 * * * * /bin/date > /tmp/date.out 2>&1 */55 * * * * /bin/date > /tmp/date.out 2>&1Backup crontab and display contents. Extra precaution in case crontab.save.dinh is removed.
[oracle@racnode-dc1-1 ~]$ crontab -l > crontab.save.dinh; cat crontab.save.dinh */05 * * * * /bin/date > /tmp/date.out 2>&1 */15 * * * * /bin/date > /tmp/date.out 2>&1 #*/25 * * * * /bin/date > /tmp/date.out 2>&1 */35 * * * * /bin/date > /tmp/date.out 2>&1 */45 * * * * /bin/date > /tmp/date.out 2>&1 */55 * * * * /bin/date > /tmp/date.out 2>&1Remove crontab.
[oracle@racnode-dc1-1 ~]$ crontab -r; crontab -l no crontab for oracleRestore crontab.
[oracle@racnode-dc1-1 ~]$ crontab crontab.save.dinh; crontab -l */05 * * * * /bin/date > /tmp/date.out 2>&1 */15 * * * * /bin/date > /tmp/date.out 2>&1 #*/25 * * * * /bin/date > /tmp/date.out 2>&1 */35 * * * * /bin/date > /tmp/date.out 2>&1 */45 * * * * /bin/date > /tmp/date.out 2>&1 */55 * * * * /bin/date > /tmp/date.out 2>&1If you are lazy like me, then backup can be done in one command.
[oracle@racnode-dc1-1 ~]$ crontab -l > crontab.save.dinh; cat crontab.save.dinh; crontab -r; crontab -l */05 * * * * /bin/date > /tmp/date.out 2>&1 */15 * * * * /bin/date > /tmp/date.out 2>&1 #*/25 * * * * /bin/date > /tmp/date.out 2>&1 */35 * * * * /bin/date > /tmp/date.out 2>&1 */45 * * * * /bin/date > /tmp/date.out 2>&1 */55 * * * * /bin/date > /tmp/date.out 2>&1 no crontab for oracle [oracle@racnode-dc1-1 ~]$
