我试图在我的ubuntu14.04.5lts机器上运行redis
首先，我做了这个命令来安装redis=>

sudo apt install redis-server

然后我安装了systemd=>

sudo apt-get install systemd

现在，我正在尝试运行以下命令=>

sudo systemctl start redis-server

我收到一条信息=>

Failed to issue method call: Unit redis.service failed to load: No such file or directory. See system logs and 'systemctl status redis.service' for details.

我的redis状态=>

root@man4-17d79b78fc6a:/# sudo systemctl status redis
redis.service 
   Loaded: error (Reason: No such file or directory)
   Active: inactive (dead)

我从以下来源获得的redis安装教程：www.digitalocean.com/community/tutorials/how-to-install-and-secure-redis-on-ubuntu-18-04
为什么我收到这个错误信息？