Instead of typing "crontab -e" I accidentally typed "crontab" and was stuck in the middle of a process so I aborted the process. Now when I go to crontab -e it's entirely blank. This isn't good at all. If I can't get it back I will need to rewrite it.
Is there any way to:
- get my crontab jobs back? are they in memory somewhere? Where are the account specific crontab files located in linux? OR
- get a log of all things that cron has done, so I can reverse engineer my crontab file. I hadn't looked at it in a long time?
5 Answers
crontab with no arguments reads a crontab file from standard input. For example, you might use:
echo "* * * * * run-this-every-minute" | crontabOnce you've clobbered your crontab (i.e., crontab -l shows nothing), there's no good way to get it back.
On my system (Ubuntu 11.04), personal crontabs are stored in /var/spool/cron/crontabs/<USER> -- but that's what you clobbered, so that won't do you any good. (The path could be different on your system.)
I see entries in /var/log/syslog for commands executed by cron; you might be able to reconstruct your crontab from that (or your system's equivalent, if any), but it's going to be tedious.
Here's what I do to avoid this kind of problem:
I keep my crontab in a separate file, maintained in a source control system. I install it only by running
crontab filenameI never use crontab -e. If I accidentally clobber my crontab, I can just reload it from the file. (Well, hardly ever; I sometimes use crontab -e to make temporary changes, knowing that I can restore the current version later.)
Script for full crontab recovery
I made a PHP script that does a full recovery of your crontab, based on the log.
It outputs a single instance of every cron command run by the user for the last week.
I put it here
Here is a sample output:
perl ~/sorttv/sorttv.pl
/usr/local/bin/flexget
bash ~/scripts/sort_sports.sh
~/scripts/play_recently_added.shI'm sorry, but I can't help asking the obvious: why not restore it from backup?
Er, sorry, I see that was suggested already.
If your EDITOR envrionment variable is EDITOR=vi, try
vi -rto recover the session. Do not directly write the saved session, if you get one, to your crontab directory. Use it as a guide to recreate your crontab using
crontab -eNote: Since you did not specify an OS, Solaris and other UNIX OSes do not recognize changes to crontab files except those created through crontab -e. If I remember correctly, Linux does.
1Great answer from @Keith Thompson - good idea reconstructing from /var/log/syslog!
I also accidentally clobbered my user crontab but was able to reconstruct it with the following script-fu
mkdir ~/syslog
sudo cp /var/log/syslog* ~/syslog/
sudo chmod 777 ~/syslog/*
cat ~/syslog/* | grep "(username)" | grep -o "CMD.*" | sort | uniqwhere username should be replaced with the user whose crontab you want to reconstruct.
Note that you may need to gunzip the contents of your /var/log/syslog.x.gz files first if the logs have been compressed (ubuntu zips up syslog.2+)
This will also only get commands that are still in the logs, which will be about the last 7 days... so if you have a monthly task that didn't run... that one is probably gone
