I have trouble installing mongodb on linux system

  mongodb, question

Operating system: CentOS 7.4 64-bit
When installing the official website step by step, there is the most time to run it.

sudo service mongod start

The result of the operation is:

Redirecting to /bin/systemctl start mongod.service
Failed to start mongod.service: Unit not found.

I don’t know where the problem is. It’s very strange. Do you have any bosses to tell me

You also posted your installation steps. According to the official website installation is certainly no problem, the official installation package with systemd script