[SOLVED] flock with crontab is not working properly

Issue

I have a crontab job, that looks like this:

*/5 * * * *  /usr/bin/flock -w 0 /home/partners_perfluence_delivery/cron.lock cd /home/partners_perfluence_delivery && /usr/bin/python3 /home/partners_perfluence_delivery/main.py

When I run script main.py manually, everything works like a charm. When I'am trying to use crontab job, lock-file is created, but when I am looking for a job with ps aux | grep main.py I see nothing in the output as well as requests used in main.py are not being made

What am I possibly doing wrong?

Solution

flock is executing cd in a subprocess, then releasing the lock when that completes. If the Python script needs to be run in that directory, it doesn't happen because the directory was only changed in the subprocess.

You should execute cd and python in the same shell process using flock -c.

*/5 * * * *  /usr/bin/flock -w 0 /home/partners_perfluence_delivery/cron.lock -c 'cd /home/partners_perfluence_delivery && /usr/bin/python3 /home/partners_perfluence_delivery/main.py'

Answered By - Barmar