Shell Programming and Scripting

is there a way to efficiently monitor logfiles that do not have a date or time format? i have several logs on several different servers that need to be monitored. but i realized writing a script for this would be very complex and time consuming giving the variety of things i need to check for i.e. check if log file exist, check if log has read permissions, check strings, etc.

i know log file monitoring is essential on basically all UNIX systems. my question is, what method are some of you using, and which ones are the easiest to set up and use? and to go back to my first question, how do you monitor the logs that simply do not have a date and time in them?

OS: linux, sunos, hpux, aix
bash/sh

It totally depends on what exactly you want to monitor in your log file. Here is one approach that I want to suggest:-

E.g. if you want to monitor a log for any new occurrence of an exception or error message and it does not have date and time information, then you can go by line number. Each time script find an exception or error message it logs it to a file with date, time & line number information and script uses this file content, compares it during its next run to identify another occurrence.

thank you so much for the suggestion! i've searched everywhere on this, but there doesn't appear to be a simple straight forward solution. i'm going to have to write something. thanks again!