Conditional block in crontab

Question

Is it possible to put an "if" statement in a user's crontab, or is there another sensible way to organise lots of conditional cron jobs? From the end user's perspective, it would be easiest if they could use the normal crontab and just put their entries between two lines if possible.

Ideally something like:

if [ something ]; then
* * * * * /usr/bin/php /path/to/file.php
0 0 * * * /usr/bin/php /path/to/file2.php
*/5 * * * * /root/script.sh
fi

Answer 1

It's not possible to do precisely this.

What you can do however, is to make a script like /usr/local/bin/check_live - which exits with status code 0 if the server is currently live, and nonzero if it's not.

You can then have crontab lines like:

* * * * * /usr/local/bin/check_live && /usr/bin/php /path/to/file.php
0 0 * * * /usr/local/bin/check_live && /usr/bin/php /path/to/file2.php
*/5 * * * * /usr/local/bin/check_live && /root/script.sh

Answer 2

I wouldn't recommend putting it in crontab file. Instead, create a script where you'll set your conditions and then put it in the crontab file. You'll have a much cleaner and organized setup.