crystal (pkg config not found)

Re-learning ruby (or, I should say, in greater depth), so I started playing with Crystal again. Came across this bug though:

crystal run src/tsend.cr
sh: 1: pkg-config: not found

Fortunately, it’s an easy fix.

CMAKE Could NOT find PkgConfig (missing: PKG_CONFIG_EXECUTABLE)

sudo apt-get install pkg-config