> Using pipefail makes it more likely your script will fail unexpectedly and without a known cause. You have to check PIPELINE to see which command in a string of pipes failed and then report on it. This is often pointless, because usually just checking the output of the last pipe will tell you whether you got what you wanted.

Really? In this script's "ps aux | grep -c rsync" for example, if "ps" fails, you'll just get 0 without the grep failing.

(Speaking of that line: chasil's completely right that it's much better to use "flock" than "ps" for locking...)