in fact, there is nothing wrong with my installation, the only problem is that it is different from the example given in the official documents, which makes me think I am wrong.
trying to go down is not a big problem.
excuse me.

the server is the Ali cloud server of centos7 that has just initialized the disk.

all the steps follow the installation tutorial on the official website:

https://dev.mysql.com/doc/mys.

error occurred before starting the mysql server in step 4, I think it should all be OK

[root@Adam mysql]-sharp sudo service mysqld start
Redirecting to /bin/systemctl start  mysqld.service


[root@Adam mysql]-sharp sudo service mysqld status
Redirecting to /bin/systemctl status  mysqld.service
mysqld.service - MySQL Server
   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled)
   Active: active (running) since Thu 2018-05-03 14:48:47 CST; 19min ago
     Docs: man:mysqld(8)
           http://dev.mysql.com/doc/refman/en/using-systemd.html
  Process: 1180 ExecStart=/usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS)
  Process: 1107 ExecStartPre=/usr/bin/mysqld_pre_systemd (code=exited, status=0/SUCCESS)
 Main PID: 1184 (mysqld)
   CGroup: /system.slice/mysqld.service
           1184 /usr/sbin/mysqld --daemonize --pid-file=/var/run/mysqld/mysql...

May 03 14:48:47 Adam systemd[1]: Started MySQL Server.
May 03 15:06:53 Adam systemd[1]: Started MySQL Server.

View error log

cat /var/log/mysqld.log

get:

2018-05-03T06:48:40.433045Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2018-05-03T06:48:42.653691Z 0 [Warning] InnoDB: New log files created, LSN=45790
2018-05-03T06:48:42.987991Z 0 [Warning] InnoDB: Creating foreign key constraint system tables.
2018-05-03T06:48:43.053417Z 0 [Warning] No existing UUID has been found, so we assume that this is the first time that this server has been started. Generating a new UUID: 0500bdb0-4e9e-11e8-a47e-00163e08240e.
2018-05-03T06:48:43.055498Z 0 [Warning] Gtid table is not ready to be used. Table "mysql.gtid_executed" cannot be opened.
2018-05-03T06:48:43.055946Z 1 [Note] A temporary password is generated for root@localhost: *wGve+dHu1Y(
2018-05-03T06:48:46.745567Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2018-05-03T06:48:46.747041Z 0 [Note] /usr/sbin/mysqld (mysqld 5.7.22) starting as process 1184 ...
2018-05-03T06:48:46.750539Z 0 [Note] InnoDB: PUNCH HOLE support available
2018-05-03T06:48:46.750562Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2018-05-03T06:48:46.750570Z 0 [Note] InnoDB: Uses event mutexes
2018-05-03T06:48:46.750574Z 0 [Note] InnoDB: GCC builtin __atomic_thread_fence() is used for memory barrier
2018-05-03T06:48:46.750578Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.3
2018-05-03T06:48:46.750581Z 0 [Note] InnoDB: Using Linux native AIO
2018-05-03T06:48:46.750849Z 0 [Note] InnoDB: Number of pools: 1
2018-05-03T06:48:46.751127Z 0 [Note] InnoDB: Using CPU crc32 instructions
2018-05-03T06:48:46.752547Z 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
2018-05-03T06:48:46.763777Z 0 [Note] InnoDB: Completed initialization of buffer pool
2018-05-03T06:48:46.766286Z 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
2018-05-03T06:48:46.778460Z 0 [Note] InnoDB: Highest supported file format is Barracuda.
2018-05-03T06:48:46.788598Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2018-05-03T06:48:46.788640Z 0 [Note] InnoDB: Setting file "./ibtmp1" size to 12 MB. Physically writing the file full; Please wait ...
2018-05-03T06:48:46.994265Z 0 [Note] InnoDB: File "./ibtmp1" size is now 12 MB.
2018-05-03T06:48:46.995082Z 0 [Note] InnoDB: 96 redo rollback segment(s) found. 96 redo rollback segment(s) are active.
2018-05-03T06:48:46.995093Z 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active.
2018-05-03T06:48:46.996046Z 0 [Note] InnoDB: Waiting for purge to start
2018-05-03T06:48:47.046201Z 0 [Note] InnoDB: 5.7.22 started; log sequence number 2589318
2018-05-03T06:48:47.046511Z 0 [Note] Plugin "FEDERATED" is disabled.
2018-05-03T06:48:47.051515Z 0 [Note] InnoDB: Loading buffer pool(s) from /var/lib/mysql/ib_buffer_pool
2018-05-03T06:48:47.054110Z 0 [Note] InnoDB: Buffer pool(s) load completed at 180503 14:48:47
2018-05-03T06:48:47.055609Z 0 [Note] Found ca.pem, server-cert.pem and server-key.pem in data directory. Trying to enable SSL support using them.
2018-05-03T06:48:47.055818Z 0 [Warning] CA certificate ca.pem is self signed.
2018-05-03T06:48:47.057502Z 0 [Note] Server hostname (bind-address): "*"; port: 3306
2018-05-03T06:48:47.057539Z 0 [Note] IPv6 is available.
2018-05-03T06:48:47.057549Z 0 [Note]   - "::" resolves to "::";
2018-05-03T06:48:47.057570Z 0 [Note] Server socket created on IP: "::".
2018-05-03T06:48:47.066966Z 0 [Note] Event Scheduler: Loaded 0 events
2018-05-03T06:48:47.067077Z 0 [Note] /usr/sbin/mysqld: ready for connections.
Version: "5.7.22"  socket: "/var/lib/mysql/mysql.sock"  port: 3306  MySQL Community Server (GPL)

the linux system is really a pain in the neck. There is always something wrong with the installation according to the method of the official website.
another question I"d like to ask the elder who can solve this problem. How did you get this far?
Thank you