Answers for "ubuntu 20 error Starting mongodb (via systemctl): mongodb.service."

Failed to enable unit: Unit file mongod.service does not exist.

> systemctl list-unit-files --type=service
...
mongodb.service             disabled
...

Failed to enable unit: Unit file mongod.service does not exist.

> systemctl list-unit-files --type=service 
...
mongodb.service             enabled
...