cron different form interactive

namit · 03-04-2008, 02:36 PM

Hey just wondering could anyone help me

Have script that runs perfectly when i just run ./grabJob.py through cron it seams to run but when it get to the popen it stops or throws error.

If run just ./grabJob.py it works ok and outputs

Code:

en:/var/www/apache2-default# ./grabJob.py
Grabbing Jobs
running create
Jobs runnning....
Creating environment ckortenhorst1
/usr/bin/xen-create-image --hostname=ckortenhorst1 --ip=192.168.0.111
DONE

./grabJob.py

Code:

        # RUN all the Create ENVIRONMNET commands here
            run="/usr/bin/xen-create-image --hostname=%s --ip=%s" % (hostname, ipadd[0])
            print run;
            try:
                fs=os.popen(run)
                for file in fs:
                    error = error + file

Through cron it does not work through bash it does work.

Can anyone help

found that crons env is different than bash but not sure how to change this

Code:

xen:~# diff intteractiv crons_env 
1,7c1,2
< TERM=xterm-color
< SHELL=/bin/bash
< SSH_CLIENT=192.168.10.140 49597 22
< SSH_TTY=/dev/pts/1
< USER=root
< MAIL=/var/mail/root
< PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
---
> SHELL=/bin/sh
> PATH=/usr/bin:/bin
10,11d4
< PS1=\h:\w\$ 
< SHLVL=1
13c6
< LS_OPTIONS=--color=auto
---
> SHLVL=2
15d7
< SSH_CONNECTION=192.168.10.140 49597 192.168.0.93 22

bigrigdriver · 03-04-2008, 03:13 PM

As a test, try running it from a terminal, in background so that the terminal is immediately released back to you. Does it stil choke up?

BrianK · 03-04-2008, 03:21 PM

Does it run at all? Does it give you an error message? What's the first line of your python script (the one that says how to run it, i.e. "#!/usr/bin/env python")?

It's probably a path issue, assuming you can get a cron to run at all. You can get a cron running, right? Like, if you make a cron that echos `date` to some file every minute, it works, yes?

namit · 03-04-2008, 03:48 PM

Yes sorry should have explained it does run upto the xen-create

first line is
#!/usr/bin/python

Yup cron is working no problem, can i just copy and post these environmnet variables into crontab -e?

SHELL=/bin/bash
USER=root
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PWD=/root
LANG=en_IE.UTF-8
PS1=\h:\w\$
SHLVL=1
HOME=/root
LOGNAME=root

?

bigrigdriver · 03-04-2008, 04:38 PM

If I remember correctly, there is another possible issue: the timing of events in the script.

When run in the terminal, the script gets to fs=os.popen(run) and waits until that part is complete before moving on to for file in fs:

When run as a background process, it may not wait as it would in a terminal. So, if you know how long it takes the fs=os.popen(run) to run, try putting a sleep in there for the appropriate amount of time (before the for loop), then try it again as a cron job to see if it runs.

I could be off base, but I seem to remember something to that effect from my Unix class a few years ago.

namit · 03-04-2008, 09:12 PM

THANK you so so much just added this to crontab and works a treat.

xen:/var/www/apache2-default# crontab -e
# m h dom mon dow command
SHELL=/bin/bash
PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin

Thank you

fvu · 03-05-2008, 02:07 PM

You can also test the program via the batch command. The batch command executes commands just like cron – with no terminal connected, but at a later time when system load levels permit. Using batch saves you the trouble of modifying crontab for just a test-run.

Example run:

Code:

$> batch
warning: commands will be executed using /bin/sh
at> touch /tmp/now~  
at> ^D
$> ls -l /tmp/now~
-rw-r--r-- 1 user group 0 2007-11-15 21:26 /tmp/now~
$>

See also:
At and Batch - Red Hat Documentation

Freddy Vulto
http://fvue.nl