Shell Programming and Scripting

I have a log which is configured as follows:

date time code1 notes: code2

A monthly job is run based on information supplied from this log. The end of each monthly job is clearly indicated by a code within 'code1'. At this time someone is performing a less on the log, moving to the end, performing a backward search (?string) for the string and deleting everything above this point.

I am writing a script that will first reverse the order of the log (tail -r file > new file) [placing newest entries first] but I am not sure how to manipulate the file from there. I need to find the code within the code1 field and delete to the bottom.

You could pipe it through:

Code:

awk '{ print $0; if($3 == "code") { exit }}'

where $3 is the field number, and "code" is the code to match.
So the whole command could be:

Code:

tail -r file | awk '{ print $0; if($3 == "code") { exit }}' > newfile

Many thanks for your help - this was exactly what I needed and thanks for the introduction to 'tac'.