Move lines matching a pattern from one file to another

Question

I want to move lines matching certain pattern from file1 to file2. Analogous to operation cut and paste from one file to another in windows

Answer 1

I like the other answers, but just an (obvious) alternative approach in case you are worried about making a mistake in your pattern and want an easy way to rollback:

grep    'bar' file1 > file2
grep -v 'bar' file1 > file3

Once you're happy with your results (hint: tee instead of > will allow you to see what's getting written to your files):

mv file3 file1

Generally I prefer perl to do substitution like in the above answer, but when the regex idiom gets too complicated and you are semi-blindly copying and pasting commands you don't understand, you're not in control of your precious data.