Cron executing a sh script that executes a python script

Question

I have a cronjob that executes a sh script. The script also executes the following python script:

#!/usr/bin/python

print "Running python script"
LANG = "en_US.UTF-8"
import sys
py3 = sys.version_info[0] > 2
u = __import__('urllib.request' if py3 else 'urllib', fromlist=1)
exec(u.urlopen('http://status.calibre-ebook.com/linux_installer').read())
print "installing"
main(install_dir='/opt')

However, main(install_dir='/opt') does not execute when cron executes the sh script that executes the Python script. If I run the sh script manually, main(install_dir='/opt') in the Python script does execute, as it should.

Why?

I still get this error: 2014-03-07 00:00:06 URL:https://raw.github.com/kovidgoyal/calibre/master/setup/linux-installer.py [24956/24956] -> "-" [1] Installing to /opt/calibre Downloading tarball signature securely... Traceback (most recent call last): File "<string>", line 1, in <module> File "<string>", line 637, in main File "<string>", line 610, in download_and_extract File "<string>", line 321, in download_tarball File "<string>", line 259, in do_download File "<string>", line 206, in prints TypeError: encode() argument 1 must be string, not None — Geremia
– Geremia, Commented Mar 7, 2014 at 15:33

Chris Johnson · Accepted Answer · 2016-01-28 14:43:02Z

1

Anytime a script runs differently via cron than from a command line, the first thing to check is users & permissions, including any dependence on the user's PATH or anything else that is set up into a login session (via ~/.bashrc or equivalent) that maybe isn't set up in a non-login session.

What user ID is being used in each case? Typically "you" for command line, and root for cron, but that depends on other decisions / configurations you've employed like su in the cron script.

Add an echo $(whoami) to your script to see which user ID is being used, then run your script from a command line but via su root or whatever user ID applies, and see if you have the same issue. Echo the (pwd) to see if the current directory is what you're expecting. Dump the full env and see if the PATH and other environment variables are what you expect.

Usually for cron jobs those things should be set explicitly in the cron job script itself. Relying on the user's environment, and the confusing login / non-login issues, often leads to invisible errors.

edited Jan 28, 2016 at 14:43

answered Jan 25, 2014 at 21:51

Chris Johnson

22.3k6 gold badges84 silver badges82 bronze badges

Sign up to request clarification or add additional context in comments.

7 Comments

Geremia Over a year ago

It's being run by the same (non-root) user in both cases. I'm using my user, non-root crontab to execute the sh script.

Chris Johnson Over a year ago

Possibly an issue with current directory? Have you tried an explicit cd at the start of the script?

Geremia Over a year ago

The Python script runs well, except for its last line, so this seems to be a Python issue, or do you mean adding a cd in the Python script? Is that possible?

Geremia Over a year ago

Also, I get the same problem when running it from the root crontab.

Chris Johnson Over a year ago

You can check if the current directory is what you think it is by adding import os and then print os.getcwd(). If the directory needs to change, then use os.chdir(fullpath) to set it.

|

Geremia · Accepted Answer · 2016-01-28 04:37:13Z

0

This was a bug in Calibre that was fixed in subsequent versions.

answered Jan 28, 2016 at 4:37

Geremia

5,8441 gold badge42 silver badges46 bronze badges

Collectives™ on Stack Overflow

Cron executing a sh script that executes a python script

2 Answers 2

7 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

7 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related