topic Re: Tail and Grep in Operating System - HP-UX

Tail and Grep

Brahnda A. Eleazar — Thu, 18 Jun 2009 02:43:48 GMT

Peace all,

I was trying to use tail and grep for log monitoring.
Such as this:
tail -f my.log | grep error

It's working in Linux but doesn't seem so in HP-UX 11.23.

Any help?

Thanks,
=adley=

Re: Tail and Grep

Suraj K Sankari — Thu, 18 Jun 2009 03:35:49 GMT

Hi,
What is the output you are getting ?

Suraj

Re: Tail and Grep

Nido — Thu, 18 Jun 2009 03:36:28 GMT

Hi,

>>>>tail -f my.log | grep error
Its working for me on both Linux and HPUX 11.23,11.11.

Anyway tail -f option is ignored when reading from a pipe.
Instead of "-f" option you can put a sleep argument in your script for the desired time.

Cheers!!

Re: Tail and Grep

Venkatesh BL — Thu, 18 Jun 2009 03:41:06 GMT

Looks like with '-f' option waits for further input even after the EOF is reached(see manpage). So, it will show you the pattern, but, won't terminate.

What is the difference you are seeing? Can you post both the outputs?

Re: Tail and Grep

Brahnda A. Eleazar — Thu, 18 Jun 2009 03:50:34 GMT

Peace all,

Thanks for the inputs.

The problem is there is no output.
It simply hung after I pressed ENTER (it's been like this for 5 minutes almost) :)

Well, I asked this because I wanted to monitor IPMON logs.
But, I think I'll just reroute the ipmon logs to a separate file instead. :)

Thanks,
=adley=

Re: Tail and Grep

Venkatesh BL — Thu, 18 Jun 2009 04:01:18 GMT

May be there is no 'error' thus far!

Re: Tail and Grep

Brahnda A. Eleazar — Thu, 18 Jun 2009 04:06:18 GMT

Peace,

I thought about that.
The thing is, I did try to simulate an error attempt.

For example, if the ipf rule is this:
pass in quick on lan8 proto tcp from 10.192.x.y to any port = NNNN keep state
block in log quick on lan8 proto tcp from any to any port = NNNN keep state

I tried attempting to the same port from, say, 10.192.x.z, I did get rejected by ipf. But no logs of the blocking.

But nevermind, I have re-routed the logs to another file instead of syslog.log; so I can tail there instead easily. :)

Really appreciate everyone's help!

Thanks,
=adley=

Re: Tail and Grep

Suraj K Sankari — Thu, 18 Jun 2009 05:27:11 GMT

Hi Again,

>>tail -f my.log | grep error

will open your my.log and waiting for any line which is having error insert into the my.log file.

if your my.log file will not getting any error string then you will not getting any error.

Suraj

Re: Tail and Grep

Aneesh Mohan — Thu, 18 Jun 2009 06:03:54 GMT

see..

# echo "error $(date)" >> /tmp/pv

# tail -f /tmp/pv |grep error
error Thu Jun 18 10:00:49 UTC 2009

Aneesh

Re: Tail and Grep

john korterman — Thu, 18 Jun 2009 06:37:32 GMT

Hi,

perhaps you should try a non-case sensitive search:

# tail -f my.log | grep -i error

regards,
John K.

Re: Tail and Grep

Brahnda A. Eleazar — Thu, 18 Jun 2009 07:45:28 GMT

Peace all,

Turns out you're all correct.
It did work in HP-UX 11.23.
The problem for me, perhaps, was that I'm trying to tail and grep from a very big text file and it took quite a long time to finish (I didn't bother waiting though).

I tried the exact command to a much smaller text file and it worked! :)

Sorry for the false alarm.

Thanks a lot,
=adley=

Re: Tail and Grep

Brahnda A. Eleazar — Thu, 18 Jun 2009 07:46:54 GMT

Thread closed.

Thanks everyone.