Can PHP detect if its run from a cron job or from the command line?

Question

I'm looking for way to PHP to detect if a script was run from a manual invocation on a shell (me logging in and running it), or if it was run from the crontab entry.

I have various maintenance type scripts written in php that i have set to run in my crontab. Occasionally, and I need to run them manually ahead of schedule or if something failed/broken, i need to run them a couple times.

The problem with this is that I also have some external notifications set into the tasks (posting to twitter, sending an email, etc) that I DONT want to happen everytime I run the script manually.

I'm using php5 (if it matters), its a fairly standard linux server environment.

Any ideas?

Answer 1

Instead of detecting when the script is run from the crontab, it's probably easier to detect when you're running it manually.

There are a lot of environment variables (in the $_ENV array) that are set when you run a script from the command line. What these are will vary depending on your sever setup and how you log in. In my environment, the following environment variables are set when running a script manually that aren't present when running from cron:

• TERM
• SSH_CLIENT
• SSH_TTY
• SSH_CONNECTION

There are others too. So for example if you always use SSH to access the box, then the following line would detect if the script is running from cron:

$cron = !isset($_ENV['SSH_CLIENT']);