Python脚本从crontab失败

Question

I've gone through multiple threads, but I still can't seem to find my problem.

I'm building a really simple Twitter bot that I'd like to fire every hour, on the hour with a cron job from a Raspberry Pi. Here's my crontab:

PYTHONPATH=/usr/bin/python
MAILTO=*myemail*
00 * * * * /home/username/directory/my_script.py >> /var/log/cron.log

Then the script:

#! /usr/bin/env python
import sys
from twython import Twython, TwythonError
from pymarkovchain import MarkovChain

#TWITTER ACCESS
apiKey = KEY
apiSecret = SECRET
accessToken = TOKEN
accessKey = KEY

#text to pull
text = open('/home/username/directory/text.txt').read()

#Generate database and frequency table
mc = MarkovChain('/home/username/directory/markov')
mc.generateDatabase(text)
tweet = mc.generateString()

api = Twython(apiKey,apiSecret,accessToken,accessKey)

try:
    api.update_status(status=tweet)
except TwythonError as e:
    print e

The first thing I checked was all of my referenced files to make sure they were absolute references. Then, I checked to make sure my file paths were correct. I'm really stumped here. Running the script from command line with the full path works as expected. Any thoughts are appreciated.

Answer 1

After trying the suggestions above and reading countless articles, I learned that cron has to run as root, not as the user. I checked the logs and saw that the user calling the script was the owner of the file, not root. So, running chmod a+x my_script.py took care of it.

Thanks for all the suggestions - especially those getting the errors to the correct log file.

Answer 2

To debug better, you might want to redirect stderr:

00 * * * * /home/username/directory/my_script.py >> /tmp/cron.log 2>&1
# or
00 * * * * /home/username/directory/my_script.py >> /tmp/cron.log 2>/tmp/cron-error.log

(I also changed the path there to make sure your cron user has permission to write output.)

Another thing you could try is run the script with Python in cron:

00 * * * * python /home/username/directory/my_script.py >> /tmp/cron.log 2>&1