how to grab some information from log file to make a new file

Dear Liu.

The grep command which Igave you exactly does what Try this

Search for grep -A option and pipes in linux.

The command which I gave you:

“grab the 5001 lines that appear after “step” and put that (or pipe it) in to log.txt”

This is what does.

This is not a lammps related question at all.

So please put an effort to atleast take the suggestions which people give on the forum.

This will be my last e-mail in this issue.

Good luck