How to check if docker daemon is running?

I made a little Script (Mac Osx) to ensure Docker is running by checking the exit code of docker stats.

#!/bin/bash
#Open Docker, only if is not running
if (! docker stats --no-stream ); then
  # On Mac OS this would be the terminal command to launch Docker
  open /Applications/Docker.app
 #Wait until Docker daemon is running and has completed initialisation
while (! docker stats --no-stream ); do
  # Docker takes a few seconds to initialize
  echo "Waiting for Docker to launch..."
  sleep 1
done
fi

#Start the Container..

You have a utility called pgrep on almost all the Linux systems.

You can just do:

pgrep -f docker > /dev/null || echo "starting docker"

Replace the echo command with your docker starting command.

This works for me on Ubuntu

$ systemctl status docker