Cron执行执行python脚本的sh脚本

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?

Answer 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.

Answer 2

这是Calibre中的一个错误，已在后续版本中修复。