cron.daily, cron.hourly etc
On Ubuntu, you can put a shell script in one of these folders:
/etc/cron.daily/etc/cron.hourly/etc/cron.monthly/etc/cron.weekly
...and it will be executed daily, hourly etc.
Or, it should be executed daily, weekly, hourly etc.
A couple of gotchas:
- The file must have execute permission (see chmod -
test -x /file/name) - The file must not have a file extension. E.g. no ".sh" on the end of the file. (It's the dot that isn't allowed.)
If you add a file to /etc/cron.daily and you want to know if it will be run, try this:
run-parts --test /etc/cron.daily
...its name should be included in the output.
There is no magic to the /etc/cron.daily etc folders. You can see how they work by looking at /etc/crontab. Here's the content on a machine I know...
# /etc/crontab: system-wide crontab
# Unlike any other crontab you don't have to run the `crontab'
# command to install the new version when you edit this file
# and files in /etc/cron.d. These files also have username fields,
# that none of the other crontabs do.
SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin
# m h dom mon dow user command
17 * * * * root cd / && run-parts --report /etc/cron.hourly
25 6 * * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.daily )
47 6 * * 7 root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.weekly )
52 6 1 * * root test -x /usr/sbin/anacron || ( cd / && run-parts --report /etc/cron.monthly )
#
It's giving something called "anacron" the room to do the needful. But if anacron is not available it uses a command called "run-parts" to cron-ify the scripts in the daily/weekly/monthly folders.
"anacron" is a tool that is usually present, and it also takes responsibility for running missed jobs, if there were missed jobs.