An example shell script I'm using: lsof -i :80 | grep node | awk '{ printf $2 }'

What this should print out is the PID of the node process running on port 80; instead it returns awk: line 1: no arguments in call to printf. I can recreate this error by deleting the $2 and running it on my terminal. I suspect that shelljs or node is incorrectly escaping or interpolating the $2 variable; I haven't figured out the magical number of slashes to escape it properly.