Negative matching using grep (match lines that do not contain foo)

You can also use awk for these purposes, since it allows you to perform more complex checks in a clearer way:

Lines not containing foo:

awk '!/foo/'

Lines containing neither foo nor bar:

awk '!/foo/ && !/bar/'

Lines containing neither foo nor bar which contain either foo2 or bar2:

awk '!/foo/ && !/bar/ && (/foo2/ || /bar2/)'

And so on.

grep -v is your friend:

grep --help | grep invert

-v, --invert-match select non-matching lines

Also check out the related -L (the complement of -l).

-L, --files-without-match only print FILE names containing no match

Related