Note for awk command on Mac

Today, I cleaned up redundant Docker images.

I used this command line:
docker rmi $(docker images | grep "^<none>" | awk "{print $3}")

But it does not works on macOS, only Linux.

After some hours, I found the problem, and the right command for macOS is:
docker rmi $(docker images | grep "^<none>" | awk '{print $3}')

awk on macOS isn’t same as awk on Linux. So you will use different syntaxes.