I haven't yet mastered the weird shell stdio redirection thing yet.
I want to run npm install but redirect stdout so I don't have to see all of that. (I still want to capture stderr in the terminal, I just don't want to see stdout).
npm install -D suman 1> /dev/null
npm install -D suman > /dev/null should do it. (It is standard for the redirect, only to redirect stdout)