Cron not launching python script

Question

Python script is not being run, all other functions are running and stand alone script runs but combined... nada. Initially it was */30 * * * * screen python ~/db_preset.py (Yes there was new line after)

Then I packed the script into bash script:

#!/bin/sh
if ps -ef | grep -v grep | grep db_preset.py ; then
        :
else
        date >> ~/cron_log.log
        screen python /home/account/db_preset.py     
fi

and invoked it with */30 * * * * bash ~/scripts.sh

Date gets logged, so it gets to that part but script is never launched

When I try simple cron like */2 * * * * date >> ~/cron_log.log, works just fine

Edit

I tried changing python path to /usr/local/bin/python2.7 /home/account/db_preset.py; touch ~/a_command_has_run

File gets created, so line is run afterall Code is also good when run manually

possible duplicate of Why is my crontab not working, and how can I troubleshoot it? — Jenny D, Sep 05 '14 at 19:04
~ means from home path, i played around with full path too. No change — rodling, Sep 05 '14 at 19:17
@JennyD I looked an multitude of articles on this topic, including that. No luck — rodling, Sep 05 '14 at 19:22
Why are you trying to run your script in a screen? This is almost certainly unnecessary. — Michael Hampton, Sep 06 '14 at 11:53
The problem is almost certainly your problematic use of screen. What is the purpose you are trying to accomplish with that? Have you tried it without using screen anywhere? — Christopher Cashell, Sep 08 '14 at 15:58

score 3 · Accepted Answer · answered Sep 05 '14 at 18:59

3

It's likely a pathing issue.

do: which python

It's likely to be at /usr/bin/python.

Then change your script to call the full path, ie: /usr/bin/python /home/account/db_preset.py

answered Sep 05 '14 at 18:59

Dave Holland

1,908

Come to think of it you could end up having the same issue with screen and have to call it with /usr/bin/screen as well. – Dave Holland Sep 05 '14 at 19:01
i tried full path to python2.7... stil nada – rodling Sep 05 '14 at 19:17
Seems to be working now, although there was no immediate correct feedback from the command line. – rodling Sep 10 '14 at 15:21

score 2 · Answer 2 · answered Sep 05 '14 at 19:43

Error messages from commands started through cron are sent by mail. If you look in the mail spool, you should be finding this error message: Must be connected to a terminal.

This is because you are trying to start the screen attached, which requires a terminal, and jobs run through cron have no terminal.

Starting new screen sessions from cron sounds dubious. You should probably just leave out the screen part. If you absolutely must start screen without a terminal, then start it detached. For example:

screen -dmS somename python ~/db_preset.py

i tried similar without screen before, still nothing – rodling Sep 08 '14 at 23:10 — rodling, Sep 08 '14 at 23:10

Cron not launching python script

Edit

2 Answers2