Hide all (not)matching lines in Vim

Question

Is it possible to show/hide all matching lines in vi or Vim? Not highlight but just show only those lines.

For example I have a text with word the word ERROR

Answer 1

You can use

:g/ERROR/

to print all the lines with ERROR

Also there is a Vim plugin which I saw many times but didn't use: foldsearch : fold away lines that don't match a given pattern