Cron Job Not Working

[sainiamit25]

Hi,

I am trying to run a simple shell script which executes asl in return. I am able to execute the shell scrip manually but i am not able to run the script through cron job. Can anybody help me out? Is it something to do with environment variables?My script is

#!/bin/sh
cd /opt/InCh/IP/smarts/bin
sm_adapter -s APM1 /opt/InCh/IP/smarts/local/rules/Cards.asl >> /opt/InCharge65/IP/smarts/bin/xvz.log

exit 0

Cheers,
Amit

[numberwhun]

Hi,

I am trying to run a simple shell script which executes asl in return. I am able to execute the shell scrip manually but i am not able to run the script through cron job. Can anybody help me out? Is it something to do with environment variables?My script is

#!/bin/sh
cd /opt/InCh/IP/smarts/bin
sm_adapter -s APM1 /opt/InCh/IP/smarts/local/rules/Cards.asl >> /opt/InCharge65/IP/smarts/bin/xvz.log

exit 0

Cheers,
Amit

I can see that you did a "cd" to the directory, but instead, run the sm_adapter command with the full path before it and see if it works.

Regards,

Jeff

[sainiamit25]

I can see that you did a "cd" to the directory, but instead, run the sm_adapter command with the full path before it and see if it works.

Regards,

Jeff

Hi Jeff,

Thanks for the suggestions. Yes, i tried that way also but it is not working. In frustation, i serached through the internet and found that many people face this problem. This is something to do with environment variable -- shell takes different set of environment variables and crontab takes different. But i could not understand how i can modify my script or change the environment variables. If you could through some light from that side, it would be great!!

Cheers,
Amit

[numberwhun]

Hi Jeff,

Thanks for the suggestions. Yes, i tried that way also but it is not working. In frustation, i serached through the internet and found that many people face this problem. This is something to do with environment variable -- shell takes different set of environment variables and crontab takes different. But i could not understand how i can modify my script or change the environment variables. If you could through some light from that side, it would be great!!

Cheers,
Amit

If I remember right, when the cron job runs, it is actually root that runs the job. That is why the need for absolute paths. As for the environment variables, if one of them is not getting set correctly, maybe you can put a line in the script to change it to what you need it to be.

Regards,

Jeff

[prn]

A cron job is not necessarily run as root. Any user may have a crontab and the jobs in that crontab are run as that user. However, the crontab job does not necessarily exec the user's .profile (.bash_profile, .cshrc, whatever) so the user's environment is not necessarily the same in the context of the cron job as it is for an interactive job. Jeff's suggestion of adding the full path to the sm_adapter command is the most common solution to the problem, but adding "./" to the beginning of that line should be equivalent since you already did a cd to its directory. Since that did not work, the next thing to try is to actually find out what is going wrong. :-/

You need to catch the output from your cron job (not just the output from the sm_adapter command) so make sure that your crontab entry redirects both STDOUT and STDERR to a file. How you do that will depend on your shell, but most likely, the entry in your crontab file should look something like:

30 23 * * *  /home/whatever/foo >/home/whatever/mylog 2>&1

and now the file "/home/whatever/mylog" should contain relevant information.

Since the most likely cause for your problem is your environment settings, I would suggest adding a line in your cron job to catch that too, e.g.:

#!/bin/sh
env
cd /opt/InCh/IP/smarts/bin
./sm_adapter -s APM1 /opt/InCh/IP/smarts/local/rules/Cards.asl >> /opt/InCharge65/IP/smarts/bin/xvz.log

exit 0

Addition of the "env" line should add a listing of your environmental settings to the /home/whatever/mylog file. Comparing the environment listing with the equivalent from an interactive session may also give you a clue about where your problem lies.

If it comes down to it, you may be able to execute your .profile inside the cron job to get comparable environment variables, but that's not the first thing I would suggest, and I certainly would not suggest it if you are not clear on what works in interactive and non-interactive contexts. Too many people do unsafe things in their .profiles for me to feel comfortable recommending this without knowing a lot more than I do about your situation. More likely there are relatively specific things you should add to your cron job to set the environment. I'll refrain from suggesting any of those until I know more about your situation.

HTH,
Paul

[arne]

Hi,

I am trying to run a simple shell script which executes asl in return. I am able to execute the shell scrip manually but i am not able to run the script through cron job. Can anybody help me out? Is it something to do with environment variables?My script is

#!/bin/sh
cd /opt/InCh/IP/smarts/bin
sm_adapter -s APM1 /opt/InCh/IP/smarts/local/rules/Cards.asl >> /opt/InCharge65/IP/smarts/bin/xvz.log

exit 0

Cheers,
Amit

Are you sure your your cron job is invoked at all? I once had a problem that the cron job was not invoked after I copied the crontab from one server to another. The reason was a missing newline at the the very end of the crontab ...

arne

[sainiamit25]

A cron job is not necessarily run as root. Any user may have a crontab and the jobs in that crontab are run as that user. However, the crontab job does not necessarily exec the user's .profile (.bash_profile, .cshrc, whatever) so the user's environment is not necessarily the same in the context of the cron job as it is for an interactive job. Jeff's suggestion of adding the full path to the sm_adapter command is the most common solution to the problem, but adding "./" to the beginning of that line should be equivalent since you already did a cd to its directory. Since that did not work, the next thing to try is to actually find out what is going wrong. :-/

You need to catch the output from your cron job (not just the output from the sm_adapter command) so make sure that your crontab entry redirects both STDOUT and STDERR to a file. How you do that will depend on your shell, but most likely, the entry in your crontab file should look something like:

30 23 * * *  /home/whatever/foo >/home/whatever/mylog 2>&1

and now the file "/home/whatever/mylog" should contain relevant information.

Since the most likely cause for your problem is your environment settings, I would suggest adding a line in your cron job to catch that too, e.g.:

#!/bin/sh
env
cd /opt/InCh/IP/smarts/bin
./sm_adapter -s APM1 /opt/InCh/IP/smarts/local/rules/Cards.asl >> /opt/InCharge65/IP/smarts/bin/xvz.log

exit 0

Addition of the "env" line should add a listing of your environmental settings to the /home/whatever/mylog file. Comparing the environment listing with the equivalent from an interactive session may also give you a clue about where your problem lies.

If it comes down to it, you may be able to execute your .profile inside the cron job to get comparable environment variables, but that's not the first thing I would suggest, and I certainly would not suggest it if you are not clear on what works in interactive and non-interactive contexts. Too many people do unsafe things in their .profiles for me to feel comfortable recommending this without knowing a lot more than I do about your situation. More likely there are relatively specific things you should add to your cron job to set the environment. I'll refrain from suggesting any of those until I know more about your situation.

HTH,
Paul

Thanks Paul for such a nice expalnation. I will try it it.

Cheers,
Amit

[sainiamit25]

Are you sure your your cron job is invoked at all? I once had a problem that the cron job was not invoked after I copied the crontab from one server to another. The reason was a missing newline at the the very end of the crontab ...

arne

Hi Arne,

There are some other utilities which are running through that crontab. So i think that the crontab is running. I will try to debug the problem as suggested by Paul earlier.

Thanks a lot for your inputs

Cheers,
Amit

[arne]

Hi Arne,

There are some other utilities which are running through that crontab. So i think that the crontab is running. I will try to debug the problem as suggested by Paul earlier.

Thanks a lot for your inputs

Cheers,
Amit

Still: even if other entries work, it doesn't mean that cron is able to parse the last entry ... this was the problem I had. All other entries worked just fine and there was no message about a corrupted entry or something similar. cron just silently didn't execute the last line as it was not ending in a newline.

arne

[mully31]

Still: even if other entries work, it doesn't mean that cron is able to parse the last entry ... this was the problem I had. All other entries worked just fine and there was no message about a corrupted entry or something similar. cron just silently didn't execute the last line as it was not ending in a newline.

arne

Is this behaviour just on linux?? Reason i ask is that i am moving some db's from Solaris to Linux RHE4. there is no blank line on the solaris crontab, and the last line works....

cheers
mark

[arne]

Is this behaviour just on linux?? Reason i ask is that i am moving some db's from Solaris to Linux RHE4. there is no blank line on the solaris crontab, and the last line works....

cheers
mark

I didn't check with Solaris. The copy was between two different versions of Linux. On one machine it worked, on the other it didn't.

arne