[admin@cmodb801 ~]$ mongo
MongoDB shell version v4.2.0
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
Implicit session: session { "id" : UUID("56809a6a-503d-4661-a60c-dd8461c2dc86") }
MongoDB server version: 4.2.0
Server has startup warnings:
2019-09-04T06:33:47.184+0000 I  CONTROL  [main]
2019-09-04T06:33:47.184+0000 I  CONTROL  [main] ** WARNING: Access control is not enabled for the database.
2019-09-04T06:33:47.184+0000 I  CONTROL  [main] **          Read and write access to data and configuration is un                                                     restricted.
2019-09-04T06:33:47.184+0000 I  CONTROL  [main]
mongos> sh.status()
--- Sharding Status ---
  sharding version: {
        "_id" : 1,
        "minCompatibleVersion" : 5,
        "currentVersion" : 6,
        "clusterId" : ObjectId("5d5e45a7ac9313827bdd8ab9")
  }
  shards:
        {  "_id" : "shard0000",  "host" : "shard0000/cmodb806.togewa.com:27018,cmodb807.togewa.com:27018",  "stat                                                     e" : 1 }
        {  "_id" : "shard0001",  "host" : "shard0001/cmodb808.togewa.com:27018,cmodb809.togewa.com:27018",  "stat                                                     e" : 1 }
        {  "_id" : "shard0002",  "host" : "shard0002/cmodb810.togewa.com:27018,cmodb811.togewa.com:27018",  "stat                                                     e" : 1 }
  active mongoses:
        "4.2.0" : 1
  autosplit:
        Currently enabled: yes
  balancer:
        Currently enabled:  yes
        Currently running:  no
        Failed balancer rounds in last 5 attempts:  0
        Migration Results for the last 24 hours:
                No recent migrations
  databases:
        {  "_id" : "config",  "primary" : "config",  "partitioned" : true }
                config.system.sessions
                        shard key: { "_id" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                shard0000       1
                        { "_id" : { "$minKey" : 1 } } -->> { "_id" : { "$maxKey" : 1 } } on : shard0000 Timestamp                                                     (1, 0)

mongos> sh.addShard("shard0003/cmodb812.togewa.com:27018,cmodb813.togewa.com:27018")
{
        "shardAdded" : "shard0003",
        "ok" : 1,
        "operationTime" : Timestamp(1567578860, 2),
        "$clusterTime" : {
                "clusterTime" : Timestamp(1567578860, 2),
                "signature" : {
                        "hash" : BinData(0,"AAAAAAAAAAAAAAAAAAAAAAAAAAA="),
                        "keyId" : NumberLong(0)
                }
        }
}
mongos> sh.status()
--- Sharding Status ---
  sharding version: {
        "_id" : 1,
        "minCompatibleVersion" : 5,
        "currentVersion" : 6,
        "clusterId" : ObjectId("5d5e45a7ac9313827bdd8ab9")
  }
  shards:
        {  "_id" : "shard0000",  "host" : "shard0000/cmodb806.togewa.com:27018,cmodb807.togewa.com:27018",  "stat                                                     e" : 1 }
        {  "_id" : "shard0001",  "host" : "shard0001/cmodb808.togewa.com:27018,cmodb809.togewa.com:27018",  "stat                                                     e" : 1 }
        {  "_id" : "shard0002",  "host" : "shard0002/cmodb810.togewa.com:27018,cmodb811.togewa.com:27018",  "stat                                                     e" : 1 }
        {  "_id" : "shard0003",  "host" : "shard0003/cmodb812.togewa.com:27018,cmodb813.togewa.com:27018",  "stat                                                     e" : 1 }
  active mongoses:
        "4.2.0" : 1
  autosplit:
        Currently enabled: yes
  balancer:
        Currently enabled:  yes
        Currently running:  no
        Failed balancer rounds in last 5 attempts:  0
        Migration Results for the last 24 hours:
                No recent migrations
  databases:
        {  "_id" : "config",  "primary" : "config",  "partitioned" : true }
                config.system.sessions
                        shard key: { "_id" : 1 }
                        unique: false
                        balancing: true
                        chunks:
                                shard0000       1
                        { "_id" : { "$minKey" : 1 } } -->> { "_id" : { "$maxKey" : 1 } } on : shard0000 Timestamp                                                     (1, 0)

mongos> ^C
bye

[root@cmodb801 ~]# service mongos restart
Redirecting to /bin/systemctl restart mongos.service
[root@cmodb801 ~]# service mongos status
Redirecting to /bin/systemctl status mongos.service
? mongos.service - High-performance, schema-free document-oriented database
   Loaded: loaded (/usr/lib/systemd/system/mongos.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2019-09-04 06:34:50 UTC; 5s ago
     Docs: https://docs.mongodb.org/manual
  Process: 18839 ExecStartPre=/usr/bin/chmod 0755 /var/run/mongodb (code=exited, status=0/SUCCESS)
  Process: 18836 ExecStartPre=/usr/bin/chown mongod:mongod /var/run/mongodb (code=exited, status=0/SUCCESS)
  Process: 18835 ExecStartPre=/usr/bin/mkdir -p /var/run/mongodb (code=exited, status=0/SUCCESS)
 Main PID: 18841 (mongos)
   CGroup: /system.slice/mongos.service
           +-18841 /usr/bin/mongos -f /etc/mongos.conf
           +-18845 /usr/bin/mongos -f /etc/mongos.conf
           +-18846 /usr/bin/mongos -f /etc/mongos.conf

Sep 04 06:34:50 cmodb801.togewa.com systemd[1]: Starting High-performance, schema-free document-oriented d...e...
Sep 04 06:34:50 cmodb801.togewa.com systemd[1]: Started High-performance, schema-free document-oriented database.
Sep 04 06:34:50 cmodb801.togewa.com mongos[18841]: about to fork child process, waiting until server is re...ons.
Sep 04 06:34:50 cmodb801.togewa.com mongos[18841]: forked process: 18846
Hint: Some lines were ellipsized, use -l to show in full.
[root@cmodb801 ~]# mongo
MongoDB shell version v4.2.0
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
2019-09-04T06:35:00.273+0000 E  QUERY    [js] Error: couldn't connect to server 127.0.0.1:27017, connection attem                                                     pt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused :
connect@src/mongo/shell/mongo.js:341:17
@(connect):2:6
2019-09-04T06:35:00.274+0000 F  -        [main] exception: connect failed
2019-09-04T06:35:00.274+0000 E  -        [main] exiting with code 1
[root@cmodb801 ~]# mongo --port 27017
MongoDB shell version v4.2.0
connecting to: mongodb://127.0.0.1:27017/?compressors=disabled&gssapiServiceName=mongodb
2019-09-04T06:36:02.152+0000 E  QUERY    [js] Error: couldn't connect to server 127.0.0.1:27017, connection attem                                                     pt failed: SocketException: Error connecting to 127.0.0.1:27017 :: caused by :: Connection refused :
connect@src/mongo/shell/mongo.js:341:17
@(connect):2:6
2019-09-04T06:36:02.153+0000 F  -        [main] exception: connect failed
2019-09-04T06:36:02.154+0000 E  -        [main] exiting with code 1
[root@cmodb801 ~]# mongo --port 27017 --host localhost
MongoDB shell version v4.2.0
connecting to: mongodb://localhost:27017/?compressors=disabled&gssapiServiceName=mongodb
2019-09-04T06:36:07.895+0000 E  QUERY    [js] Error: couldn't connect to server localhost:27017, connection attem                                                     pt failed: SocketException: Error connecting to localhost:27017 (127.0.0.1:27017) :: caused by :: Connection refu                                                     sed :
connect@src/mongo/shell/mongo.js:341:17
@(connect):2:6
2019-09-04T06:36:07.896+0000 F  -        [main] exception: connect failed
2019-09-04T06:36:07.896+0000 E  -        [main] exiting with code 1
[root@cmodb801 ~]# service mongos stop
Redirecting to /bin/systemctl stop mongos.service