Write data to files and pipe it into other programs the same time

Zeke Sikelianos recently shared a tweet that describes the tee command which I've never heard of. It can be used to write data to files and continue piping the same data to something else.

This is nothing world changing but in certain situations this can come in quite handy. 🎉

ls -l | tee file.txt | less 
            ||
            \/
         file.txt