grep can search for lines that don’t include word with the -v flag. We can use -e to search for multiple words, but this can be a pain when there’s a lot to search for.

The -f flag allows us to specify a file that contains a list of words/phrases to search for (one on each line) which makes it much easier to read.

For example:

grep -v -e "phrase one" -e "phrase two" -e "phrase three" <filename>

Can be rewritten as follows:

grep -v -f words.txt <filename>

where words.txt looks like:

phrase one
phrase two
phrase three

Removing the -v flag would search for only the words in the file.