[Issue, Docker, Ubuntu] Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

이슈

 docker ps 명령어 입력시 발생한 이슈

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해결

1. 다음 명령어 입력 : systemctl start docker

-> 문제 발생 :  System has not been booted with systemd as init system (PID 1). Can't operate. Failed to connect to bus : Host is down.

2. 다음 명령어 입력 : sudo /etc/init.d/docker start