Shell Programming and Scripting

Hi,
I would like to implements monitoring tool which looks at the logfile and sends me an email with error messages from the logfile.
The runtime errors are printed in logfile. The logfile also contains some warning and debugging messages.
For errors, the line will start with “Error”., the error message can contain up to 3 to 4 lines.
I want some script that implements above requirement.
I can configure cron job to run the script for every half an hour but I think the challenge is to find out the error for each time the script runs.
For example, when script runs first time, it can find out 3 errors, when it runs second time (after 30 minutes) it should not report the first 3 errors but next available errors.
Each time the scripts runs it should exclude previous errors.

I am not sure how to find out new errors that are printed after previously reported error messages.

Could you please help me in suggesting with any command or script?

Regards,

Please post:

1) Operating System and version.
2) Preferred Shell (e.g. bash, ksh, raw Bourne).
3) Representative sample logfile data, both with error lines and without error lines.
4) If it is a common logfile, the name of the package or program which produced the logfile (e.g. Oracle 9i ; syslogd ; whatever). Most commerical processes produce logfiles with each line prefixed with the date and time (not "Error").
5) Description of your email service including relevant example email command lines which work.
6) Your script attempts to date.

Please blot anything confidential with X's - including email addresses. We only need example data format and command syntax.

Though this sounds like coursework, we'll assume it is a commercial requirement for the moment.