grep

grep is a well-known, useful command line utility to filter stdin. Here are some lesser-known features.

Regular expressions

Invoking grep with the -E flag allows you to use extended regular expressions.

Matching patterns that come from a file

You might be in a use case where your patterns are defined in a file and you want to use this to grep your input. This template can be (modified and) used to achieve this.

grep $(sed "s/^/-e /;s/$/ /" patterns.txt | tr -d "\n")