Re: Monitor log file thru shell script

From: sol beach <>
Date: Tue, 8 Jul 2008 14:45:18 -0700
Message-ID: <>

I do not trust grep "whatever error strings" alert_SID.log; because new errors may be not reported to me.
I wrote a simple PERL program to report all/any lines not contained in an "ignore file".
It runs via cron every 5 minutes & starts reporting from the timestamp where it last ended.

On Tue, Jul 8, 2008 at 2:10 PM, Dan Norris <> wrote:

> I don't think you'll be able to do this since the mail command won't ever
> send the message until its STDIN is closed. Since you're using tail -f, the
> STDIN for the mail command will never be closed and you'll never get a
> message.
> When I've done similar things in the past, specifically for the alert log,
> I've done something like:
> 1. mv alert.log alert.log.YYYYMMDDHH24MM
> 2. grep "whatever error strings" alert.log.YYYYMMDDHH24MM | mail ...
> 3. find alert.log.* -mtime +10 | xargs rm
> and re-run that every process at regular intervals (daily, hourly,
> whatever).
> For other logfiles that aren't easily "rolled" like that, you may need to
> find a way to close them to rotate them and/or include the rotation process
> in the same script where you check the contents for errors.
> I'm sure there are more elegant solutions, but this (or something like it)
> has worked well for me in the past.
> Dan
> Shivaswamy / ಶಿವಸ್ವಾಮಿ wrote:
> Hello.
> I am attempting to look for a pattern in the continuously growing log file
> and mail me if match is found. (on Linux). But I am having problem.
> This is the part of the shell script
> export err1=down
> tail -f testlogfile | egrep -n "${err1}" | mail -s "Found warning"
> As you see I am using tail -f and egrep. When I run only tail -f & egrep
> part on the prompt on my testlogfile, I am able to see the output from
> egrep.
> But when I pipe it to mail, and run it on nohup on a shell script, nothing
> happens. I can see that mail process is in T state, meaning it is stopped.
> If I kill my shell script running in the background, I get the email
> notification, as expected.
> What happens here? How I can get the notification, without killing the
> process?
> If you could please help, I appreciate it.
> Thanks,
> Shiva
> --

Received on Tue Jul 08 2008 - 16:45:18 CDT

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