Mergou is in alpha with a only a few commands implemented :
ls : ls -S to sort by size (lines of code) and ls -s name to sort by name
cat with syntax coloration
find : --type function|class|module --name regex --size +/- n (lines of code)
pwd
cd (cd - and cd .. behave just like a real shell).
grep pattern [target]
less (-R by default to support colors).
jump (works like cd, but you don't have to specify the whole path, just the last leaf).
symbols (works like nm but print package names, module names, classes and functions / methods names). Symbols is context-aware but jump is not.

Nearly all commands support tab-completion.