BASH Cures Cancer

Typically, when servers are migrated or crash the data and home directories are saved. However, too often
user crontabs are not saved. I implemented a script to backup all user crontabs. You can run this in /etc/cron.daily/
or in a backup script of some kind.

First you must make a secure directory to backup the crontabs:

root@www:/data # mkdir /data/cronjobs/
root@www:/data # chmod 700 cronjobs

The script gets a list of users from /etc/passwd and loops through that list saving the output of crontab -u USERNAME -l to a file called $_USER-cron.jobs:

for _USER in `cat /etc/passwd | awk -F: '{print $1}'`
do
 crontab -l -u $_USER 2>/dev/null >/data/cronjobs/$_USER-cron.jobs
done

Or you can run the commands in a list via roots crontab and it will backup itself:

0 * * * * for _USER in `cat /etc/passwd | awk -F: '{print $1}'`; do crontab -l -u $_USER 2>/dev/null >/data/cronjobs/$_USER-cron.jobs; done

Another option is to save in the users home, I chose ~/.cron.jobs.bak. (They of course cannot use that
filename for anything else.):

for _USER in `cat /etc/passwd | awk -F: '{print $1}'`
do
 if [ -d /home/$_USER/ ]
 then
  crontab -l -u $_USER 2>/dev/null >/home/$_USER/.cron.jobs.bak
 fi
done

Or if you have a configuration where your home directories are not stored in /home/username:

for USER_HOME in `cat /etc/passwd | awk -F: '{print $1 ":" $6}'`
do
 _USER=`echo $USER_HOME | awk -F: '{print $1}'`
 _HOME=`echo $USER_HOME | awk -F: '{print $2}'`
 if [ -d $_HOME ]
 then
  crontab -l -u $_USER 2>/dev/null >$_HOME/.cron.jobs.bak
 fi
done

In addition, the last is the most portable solution.