Mongodb 安装错误汇总

1. Failed to restart mongod.service: Unit mongod.service not found.

解决方法：

Most probably unit mongodb.service is masked. Use following command to unmask it.

sudo systemctl unmask mongodb

and re-run

sudo service mongod start

vagrant@homestead:~$ sudo service mongod restart
Failed to restart mongod.service: Unit mongod.service not found.
vagrant@homestead:~$ ^C
vagrant@homestead:~$ sudo systemctl unmask mongodb
Removed symlink /etc/systemd/system/mongodb.service.
vagrant@homestead:~$ sudo service mongod start
vagrant@homestead:~$ sudo service mongod status
● mongod.service - MongoDB Database Server
   Loaded: loaded (/lib/systemd/system/mongod.service; disabled; vendor preset: enabled)
   Active: active (running) since Thu 2018-10-25 03:50:52 UTC; 5s ago
     Docs: https://docs.mongodb.org/manual
 Main PID: 6669 (mongod)
    Tasks: 19
   Memory: 37.9M
      CPU: 85ms
   CGroup: /system.slice/mongod.service
           └─6669 /usr/bin/mongod --config /etc/mongod.conf

Oct 25 03:50:52 homestead systemd[1]: Started MongoDB Database Server.
Oct 25 03:50:52 homestead mongod[6669]: 2018-10-25T03:50:52.045+0000 I CONTROL  [main] Automatically disabling TLS 1.0, to force-enable TLS 1.0 spe
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相关知识点：

屏蔽和取消屏蔽单位

我们的服务管理部分如何停止或禁用服务所看到的，但systemd还具有自动或手动标记机作为完全无法启动，通过其链接到的能力/dev/null 。 这就是所谓的掩蔽单元，并且可能用mask命令：

sudo systemctl mask nginx.service

这将防止Nginx服务自动或手动启动，只要它被屏蔽。

如果选中list-unit-files ，你会看到该服务现已被列为蒙面：

systemctl list-unit-files

. . .

kmod-static-nodes.service              static  
ldconfig.service                       static  
mandb.service                          static  
messagebus.service                     static  
nginx.service                          masked
quotaon.service                        static  
rc-local.service                       static  
rdisc.service                          disabled
rescue.service                         static

. . .

如果您尝试启动服务，您将看到如下所示的消息：

sudo systemctl start nginx.service

Failed to start nginx.service: Unit nginx.service is masked.

要再次揭露一个单元，使其可以使用，只要使用unmask命令：

sudo systemctl unmask nginx.service

这将使单元返回到先前的状态，允许它被启动或启用。