Your code works great for simple cases, but fails for files that have matches that are close together. You end up with duplicate lines being displayed.

for example try the following:

grep.pl -A 1 -B 1 test data

with the file 'data' containing:

test 1
test 2
test 3
[download]

The results are:

test 1
test 2
test 1
test 2
test 3
test 2
test 3
[download]

Also your version will parse the entire file before printing out any results. This will be slow for large files.

Still a good base to start from though...

Cheers

Cees