Can a bash script tell if it's being run via cron?

Question

Not having much luck Googling this question and I thought about posting it on SF, but it actually seems like a development question. If not, please feel free to migrate.

So, I have a script that runs via cron every morning at about 3 am. I also run the same scripts manually sometimes. The problem is that every time I run my script manually and it fails, it sends me an e-mail; even though I can look at the output and view the error in the console.

Is there a way for the bash script to tell that it's being run through cron (perhaps by using whoami) and only send the e-mail if so? I'd love to stop receiving emails when I'm doing my testing...

Answer 1

you can try "tty" to see if it's run by a terminal or not. that won't tell you that it's specifically run by cron, but you can tell if its "not a user as a prompt".

you can also get your parent-pid and follow it up the tree to look for cron, though that's a little heavy-handed.

Answer 2

I had a similar issue. I solved it with checking if stdout was a TTY. This is a check to see if you script runs in interactive mode:

if [ -t 1 ] ; then      echo "interacive mode"; else     #send mail fi 

I got this from: How to detect if my shell script is running through a pipe?

The -t test return true if file descriptor is open and refers to a terminal. '1' is stdout.