Python 脚本在 cron 作业中运行时引发错误，但不会在其他时间引发错误

Question

I have a shell script that includes execution of a python script. When I run it manually in terminal, it works fine. However when I execute the shell script in a cron job, the python script fails.

The error is apparently triggered while functions are being imported from module1 into module2. The function referenced by the error is not among the functions being imported, nor does the function where the syntax error is supposed to be elicit an error when it is executed by itself.

Here's the error that gets logged when I run the cron job:

File "/Users/me/module2.py", line 5, in <module>
    from module1 import consolidate_rankings, build_all
  File "/Users/me/module1.py", line 159
    things = {row["thing"]: row for row in rows}
                                          ^

SyntaxError: invalid syntax

The module2 script is pretty straightforward:

#!/usr/bin/env python 

from module1 import consolidate_rankings, build_all

consolidate_rankings()
build_all()

Here's the line that calls this in the shell script:

python /Users/me/module2.py

Anyone have any idea what's going on here?

Answer 1

You are probably running your script from cron with a different version of Python that doesn't support the dictionary comprehension syntax.

To fix this, either explicitly add your desired Python version in the shebang line:

#!/usr/bin/env python2.7

or launch your script from cron through the correct command:

* * * * /usr/bin/python2.7 /path/to/script.py

Answer 2

I solved this by declaring my local env in the crontab itself (since the above didn't help):

SHELL=/bin/bash
PATH=/usr/local/bin:/usr/bin:/usr/local/sbin:/usr/sbin:/usr/local/sifi/bin:/home/username/.local/bin:/home/username/bin:/home/username