Ubuntu mongodb has an exception: connect failed

  mongodb, question

By this problem make collapse, Baidu google tried still can’t, reshipment also can’t! !
I can’t find all kinds of methods. Can you give me some advice?

The error is as follows:

2017-03-21T19:16:41.552+0800 W NETWORK  [thread1] Failed to connect to 127.0.0.1:27017, in(checking socket for error after poll), reason: Connection refused
 2017-03-21T19:16:41.552+0800 E QUERY    [thread1] Error: couldn't connect to server 127.0.0.1:27017, connection attempt failed :
 connect@src/mongo/shell/mongo.js:237:13
 @(connect):1:6
 exception: connect failed

People who sincerely hope to understand can help

Eldest brother downstairs to add ~

This will happen when I start mongodb

Failed to start mongod.service: Unit mongod.service not found.

The listening port is like this

Active Internet connections (only servers)
 Proto Recv-Q Send-Q Local Address           Foreign Address         State       PID/Program name
 tcp        0      0 0.0.0.0:3306            0.0.0.0:*               LISTEN      953/mysqld
 tcp        0      0 0.0.0.0:80              0.0.0.0:*               LISTEN      973/apache2
 tcp        0      0 0.0.0.0:22              0.0.0.0:*               LISTEN      888/sshd
 udp        0      0  139.196.187.137:123     0.0.0.0:*                           961/ntpd
 udp        0      0 10.25.105.32:123        0.0.0.0:*                           961/ntpd
 udp        0      0 127.0.0.1:123           0.0.0.0:*                           961/ntpd
 udp        0      0 0.0.0.0:123             0.0.0.0:*                           961/ntpd
 udp6       0      0 :::123                  :::*                                961/ntpd

Make sure it is not turned on! , but the problem is can’t start ~ ~ ~

According to the eldest brother downstairs tips:

systemctl start mongod.service

There will be:

Failed to start mongod.service: Unit mongod.service not found.

But I mongodb is installed ~

Is mongo on? Run netstat -tunlp to see if the port is listening