Grep is a powerful tool for searching files for text matching a pattern. Have you ever
thought to use it to search for lines that do not match a search pattern?
Grep can do that! Add the
--invert-match flag, or
-v for short.
~ % cat words.txt art article cities name nonsense part tart ~ % grep art words.txt art article part tart ~ % grep art --invert-match words.txt cities name nonsense
Now you can use grep to search for presence or absence of a search pattern.