How do I get rid of “--” line separator when using grep with context lines?

Question

I have a text file named compare.txt where I want to extract the single line that follows every line that contains the pattern nmse_gain_constant.

Answer 1

Well, the A switch by default will add those characters, so it's no mystery.

man grep states:

-A NUM

    Places  a  line  containing  a  group  separator  (--)   between
    contiguous  groups  of  matches.  With the -o or --only-matching
    option, this has no effect and a warning is given.

But you can use a simple sed to clean up the result:

yourgrep | sed '/^--$/d'