I had a coworker who was having some issues. I chuckled when he had an alias for history | grep when I was checking out his env

To be fair, I also have that alias and use CTRL+R. They are useful for different scenarios. CTRL+R when I know what command I'm looking for, but can't remember the full one. `history | grep -i $TERM` when I remember some part of the command, but not exactly sure. With that, I get a list of possible candidates to choose from, instead of having to do CTRL+R repeatedly to find the command I was looking for.

Is that why his Mercurial wasn’t working?

That is heart-warming news!