I found a .mkshrc while going through my home directory dotfiles. I couldn’t even remember what it was, but it’s a MirOS Korn Shell configuration file. I didn’t know this; on NetBSD I’d used .kshrc with ksh88.

But why did I have it on my Mac?

# Add RVM to PATH for scripting. Make sure this is the 
# last PATH variable change.
export PATH="$PATH:$HOME/.rvm/bin"

That’d do it!

The MirBSD Korn Shell is also the default on Android, though I won’t hold that against it or its delightful name.