Shell Programming and Scripting

I'd like to write a script or even a good command line that can follow a very noisy log file looking for specific patterns but can also handle log roll overs in an intelligent way.

I sometimes do something like the following:

# tail -f /var/log/crazy.log | grep 'ailure' > /my/dir/crazy-failures.log

But then after some time the log will automatically roll over due to newsyslog...

Jun 28 00:00:00 qa-arc1-1 newsyslog[36074]: logfile turned over

At which that the server no longer logs messages to that file and my command no longer filters out lines with 'ailure'.

I guess one way to attack it would be to programatically search for 'logfile turned over' and automatically switch to the new log file. Is that the best option? Any suggestions?

Thanks!

---------- Post updated at 10:38 PM ---------- Previous update was at 10:31 PM ----------

I should also mention that I believe there are cases when the log file will roll over for reasons other then just hitting midnight i.e. reaching some size limit. Part of the reason I want to do this is that the default configuration will only roll over a log like 3 times before destructively removing the old log files. And the log file is to noisy to extend beyond that, anyway.

Example how to control child process.
logreader is our logreader and mainlogreader controll subreaders.

Code:

#!/usr/bin/ksh
# logreader.sh
f=/var/log/crazy.log 

function look()
{
   tail -f $f | while read line
   do
        case "$line" in
                *ailure*) do_something ;;
        esac
   done
}
#--main---
look

And main process, control subreaders

Code:

#!/usr/bin/ksh
# mainlogreader.sh
f=/var/log/syslog.log 
child=""

function start
{
    ./logreader.sh >> somelogfile.log 2>&1  &
    #save childprocess pid
    child=$!
}

function restart
{
    # stop child process using signal 15 
    kill $child
    # wait child exit signal
    wait $child
    # restart
    start
}

function look
{
   tail -f $f | while read line
   do
        case "$line" in
                *"logfile turned over"*) restart ;;
        esac
   done
}

####################################
#MAIN
####################################
# start sub logreader
start
# start my log reading
look

And now start
./mainlogreader.sh
or background process
./mainlogreader.sh > log.txt 2>&1 &