Top output to textfile not working in cronjob

Linux and Unix-Like Ubuntu
1

Hello,
If i run the following script from the cmdline it works just fine however if i run it via root cronjob it doesn't write to the file at all. It is chmod 777 now so shouldnt be any right issues.

Shellscript looks like this:

/usr/bin/top -b -n 1 -u nagios >> /var/log/test.log

Cronjob like this:

38 * * * * sh /shellScripts/test.sh >> /var/log/dummy.txt

Any idea?
Simply i want to log top output to a textfile when cronjob runs.

2

Any output would go to /var/log/test.log, not /var/log/dummy.txt. Is that where you are checking?

Also, in this case errors, would to the job owner's email (usaually).

3

Ye i am checking in the test.log file.
It writes there just fine if i do it from cmdline, not sure why cronjob isn't picking it up. Is there anyway to see what the cronjob says about it?

4

And the location of the script is definitely /shellScripts/test.sh? The directory is at least r-x for the user running the cronjob?

Can you check /var/log/cron to check the job actually ran?

I ran a text doing (albeit in RedHat) exactly what you said you are doing and have no problems.

1 Like
5

does your script have PATH variable set or at least the commands have their full paths (i.e., /bin/hostname instead of hostname , /usr/bin/rm instead of just rm , etc.)? if yes, look at something else in your current environment that will not be there should cron run your script and then account for it inside your script ...

6

Yep the directory is read and execute for users.
If i check the syslog i saw the following:

Aug  8 18:03:01 ubuntuServer CRON[21762]: (CRON) info (No MTA installed, discarding output)
Aug  8 18:05:20 ubuntuServer crontab[21804]: (root) BEGIN EDIT (root)
Aug  8 18:05:40 ubuntuServer crontab[21804]: (root) REPLACE (root)
Aug  8 18:05:40 ubuntuServer crontab[21804]: (root) END EDIT (root)
Aug  8 18:05:42 ubuntuServer crontab[21816]: (root) BEGIN EDIT (root)
Aug  8 18:06:01 ubuntuServer cron[1335]: (root) RELOAD (crontabs/root)
Aug  8 18:06:01 ubuntuServer crontab[21816]: (root) REPLACE (root)
Aug  8 18:06:01 ubuntuServer crontab[21816]: (root) END EDIT (root)
Aug  8 18:07:01 ubuntuServer cron[1335]: (root) RELOAD (crontabs/root)
Aug  8 18:07:01 ubuntuServer CRON[21841]: (root) CMD (sh /shellScripts/test.sh >/dev/null 2>&1)

Got that "No MTA Installed" so i added the "/dev/null 2>&1" just to see the difference.

---------- Post updated at 11:19 AM ---------- Previous update was at 11:13 AM ----------

I've not set any special path variables.
The entire scriptfile looks like this:

#!/bin/sh
clear
/usr/bin/top -b -n 1 -u nagios >> /var/log/test.log
7

the MTA (mail transfer agent) issue does not seem to be related to your script as it shows up in the logs more than a few minutes before your script runs and the script/program creating the log entries is doing some editing -- most likely a sql maintenance script -- while your top script does not ... besides, the script you posted does not send email so there would be no need for MTAs ...

change 2> /dev/null in your cronjob listing to 2> /shellScripts/test.err.log and see if there are any errors logged in the error log ...

1 Like
8

Hi again,
I've no idea what actually made it work but i tried a ton of stuff including both of your suggestions so something obviously did the trick. I'm grateful for your assistance, and if i find out the specific reason why it now works i'll post it here for somebody else in the future.