Crontab not executing a Python script? [duplicate]

Question

My python script is not running under my crontab.

I have placed this in the python script at the top:

#!/usr/bin/python 

I have tried doing this:

chmod a+x myscript.py 

Added to my crontab -e:

SHELL=/bin/bash PATH=/sbin:/bin:/usr/sbin:/usr/bin MAILTO=""  * * * * * /home/me/project/myscript.py 

My /var/log/cron file says:

Sep 21 11:53:02 163-dhcp /USR/SBIN/CROND[2489]: (me) CMD (/home/me/project/myscript.py) 

But my script is not running because when I check my sql database, nothing has changed. If I run it directly in the terminal like so:

python /home/me/project/myscript.py 

I get the correct result.

This is the myscript.py:

#!/usr/bin/python  import sqlite3  def main():     con = sqlite3.connect("test.db")      with con:          cur = con.cursor()          cur.execute("CREATE TABLE IF NOT EXISTS testtable(Id INTEGER PRIMARY KEY, Name TEXT)")          cur.execute("INSERT INTO testtable(Name) VALUES ('BoB')")          cur.execute("SELECT * FROM testtable")          print cur.fetchall()      if __name__ == "__main__":     main() 

Per comments: Yes, /usr/bin/python exists. I can also run the python script directly using just /home/me/project/myscript.py. /usr/bin/python /home/me/project/myscript.py works. So I don't believe this is the cause?

Answer 1

There are a lot of half answers across the internet so I thought I would capture this to save someone else some time.

First, cronjob does a poor job of telling you where this is failing. I recommend sending stderr output to a log file like this:

Crontab Command:

# m h  dom mon dow   command * * * * * /path/to/your_file.sh >> out.txt  2>&1 

As this is likely running the command as user, check home directory for the log file. Note this script runs every minute which is good for debugging.

The next issue is you probably have a path problem... as script likely is trying to execute from your home directory. This script sets the current directory, echos it to file, and then runs your program.

Try this :

Script File

#!/bin/sh cd "$(dirname "$0")"; CWD="$(pwd)" echo $CWD python your_python_file.py 

Hope this saves someone else some debugging time!!!

Answer 2

What happens when you type

/home/me/project/myscript.py into the shell?

Can you explicitly use /usr/bin/python in your crontbb command?

Can you either use an absolute path to your test.db or cd to the correct directory then execute your python script?

This is helpful to have debug statements in your python and log some data. Crontab can be very tricky to debug.