ubuntu failed to start daemon: pid file found, ensure docker is not running or delete /var/run/docker.pid code example

Example 1: failed to start daemon: pid file found, ensure docker is not running or delete /var/run/docker.pid

sudo rm /var/run/docker.pid
systemctl start docker

Example 2: failed to start daemon: pid file found, ensure docker is not running or delete /var/run/docker.pid

$  rm -rf /var/snap/docker/179/run/docker.pid
$ systemctl start docker