Python script is not running under cron, despite working when run manually

Question

I know there have been plenty of questions about this, but I've been trying things for a while with no luck. I have a simple python testscript that creates a folder with a timestamped name. It works perfectly when I run it manually, but nothing happens when I try to put it into crontab. Any idea where I'm messing up here? Here's the script: (located in /home/ec2-user/cronscripts)

from subprocess import call
from time import time
import math

call(["mkdir","derp" +str(math.floor(time()))])

and crontab -l produces the output

* * * * * python /home/ec2-user/cronscripts/testscript.py

I've tried putting 'root' into the command as well, but no dice. I've also tried some to mess around with explicitly setting the PATH variable in the script file.

From [email protected]  Wed Jun 15 19:57:01 2011
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From: [email protected] (Cron Daemon)
To: [email protected]
Subject: Cron <root@domU-12-31-38-00-AC-02> usr/bin/python /home/ec2-user/cronscripts/testscript.py
Content-Type: text/plain; charset=UTF-8
Auto-Submitted: auto-generated
X-Cron-Env: <SHELL=/bin/sh>
X-Cron-Env: <HOME=/root>
X-Cron-Env: <PATH=/usr/bin:/bin>
X-Cron-Env: <LOGNAME=root>
X-Cron-Env: <USER=root>

/bin/sh: usr/bin/python: No such file or directory

This was the last entry I found in the root mail. It seems to not be able to find python, even though it's exactly where that say it is. And when I print crontab -l, usr/bin/python does have a leading slash. Do I need to change a cron path somewhere?

Jun 15 18:02:01 domU-12-31-38-00-AC-02 CROND[5310]: (root) CMD (/home/ec2-user/cronscripts/testscript.py) Jun 15 18:03:01 domU-12-31-38-00-AC-02 CROND[5317]: (root) CMD (/home/ec2-user/cronscripts/testscript.py) — cfrederich
– cfrederich, Commented Jun 15, 2011 at 19:31
i found this in the cron log, so its clearly trying to do something — cfrederich
– cfrederich, Commented Jun 15, 2011 at 19:31
make sure root's email is setup to go somewhere and have a look at any emails this is generating. If you don't have any mail forwarding enabled run the mail command as the root user. — James C
– James C, Commented Jun 15, 2011 at 19:48
Seeing usr/bin/python as the error message suggests that somewhere along the line, you've lost a leading slash. Maybe you have #!usr/bin/python in a shebang? Very often, the problem with "it works on the command line but not in cron" comes down to 'environment' — see (amongst others) Perl script works but not via cron. — Jonathan Leffler
– Jonathan Leffler, Commented May 11, 2014 at 19:24

amit_g · Accepted Answer · 2011-06-15 19:27:16Z

6

Use fully qualified path for all commands in crontab.

0 */2 * * * /full/path/to/python /home/ec2-user/cronscripts/testscript.py

Also, all fields are *? When do you expect this to be run? The above example would run every other hr.

edited Jun 15, 2011 at 19:27

answered Jun 15, 2011 at 19:22

amit_g

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2 Comments

leonbloy Over a year ago

The above example would run every hr Nope. It will run every minute. You need to put some concrete value for the minutes field. And writing */1 in any crontab field is the same as writing *

cfrederich Over a year ago

yeah I just wanted to have it run every minute, just so I could see if it was working at all without having to wait

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