我已在测试服务器 (RHEL 7.4) 上的单独安装点（而不是默认位置）上使用 Linux 通用二进制文件配置了 MySQL 5.7.25 实例。
在这种情况下，systemd 支持必须手动配置，我就是这么做的。
我的问题是关于systemctl命令的。当我发出时systemctl status mysqld.service，输出显示“正在激活（启动）”，但服务“已成功启动”（至少根据警报日志我认为是这样）并且我没有收到提示。我必须按 Ctrl+C 才能恢复提示。对于其他服务，systemctl 状态显示活动（已启动）。另外，systemctl status mysqld.service 显示“启动后 PID 文件 /usr/local/mysql/data/mysqld.pid 不可读（还？）”。
PID 在定义的位置生成，如下面的输出所示ls -l。
我该如何处理这个问题？
以下是 的输出systemctl status mysqld.service：
> [root@localhost system]# systemctl status mysqld.service ●
> mysqld.service - MySQL Server Loaded: loaded
> (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset:
> disabled) Active: **activating (start)** since Wed 2019-03-27
> 16:58:13 IST; 5min ago
> Docs: man:mysqld(7)
> http://dev.mysql.com/doc/refman/en/using-systemd.html Process: 9307
> ExecStart=/mysql/mysql_install/mysql-5.7.25-linux-glibc2.12-x86_64/bin/mysqld
> --lc-messages-dir=/mysql/mysql_install/mysql-5.7.25-linux-glibc2.12-x86_64/share
> --daemonize --pid-file=/mysql/mysql_data/mysqld.pid $MYSQLD_OPTS (code=exited, status=0/SUCCESS) CGroup:
> /system.slice/mysqld.service
> └─9309 /mysql/mysql_install/mysql-5.7.25-linux-glibc2.12-x86_64/bin/mysqld
> --lc-messages-dir=/mysql/mysql_install/mysql-5.7.25-linux-glibc2.12-x86_64/share
> --daemonize --pid-file=/mysql/mysql_data/...
>
> Mar 27 16:58:13 localhost.localdomain systemd[1]: **Starting MySQL
> Server...** Mar 27 16:58:13 localhost.localdomain systemd[1]: **PID
> file /usr/local/mysql/data/mysqld.pid not readable (yet?) after
> start.** [root@localhost system]#
ls -l以下是数据目录的输出。
[root@localhost mysql_data]# ls -l
total 122964
-rw-r-----. 1 mysql mysql 56 Mar 27 16:14 auto.cnf
-rw-r-----. 1 mysql mysql 283 Mar 27 16:58 ib_buffer_pool
-rw-r-----. 1 mysql mysql 12582912 Mar 27 16:58 ibdata1
-rw-r-----. 1 mysql mysql 50331648 Mar 27 16:58 ib_logfile0
-rw-r-----. 1 mysql mysql 50331648 Mar 27 16:13 ib_logfile1
-rw-r-----. 1 mysql mysql 12582912 Mar 27 16:58 ibtmp1
drwxr-x---. 2 mysql mysql 4096 Mar 27 16:14 mysql
-rw-r-----. 1 mysql mysql 41256 Mar 27 16:58 mysqld.log
-rw-r-----. 1 mysql mysql 5 Mar 27 16:58 mysqld.pid
srwxrwxrwx. 1 mysql mysql 0 Mar 27 16:58 mysql.sock
-rw-------. 1 mysql mysql 5 Mar 27 16:58 mysql.sock.lock
drwxr-x---. 2 mysql mysql 4096 Mar 27 16:14 performance_schema
drwxr-x---. 2 mysql mysql 12288 Mar 27 16:14 sys
[root@localhost mysql_data]#
以下是/usr/lib/systemd/system/mysqld.service文件：
[root@localhost system]# cat mysqld.service
[Unit]
Description=MySQL
Server Documentation=man:mysqld(7)
Documentation=http://dev.mysql.com/doc/refman/en/using-systemd.html
After=network.target
After=syslog.target
[Install]
WantedBy=multi-user.target
[Service]
User=mysql
Group=mysql
Type=forking
PIDFile=/usr/local/mysql/data/mysqld.pid
# Disable service start and stop timeout logic of systemd for mysqld service.
TimeoutSec=0
# Start main service
ExecStart=/mysql/mysql_install/mysql-5.7.25-linux-glibc2.12-x86_64/bin/mysqld --lc-messages-dir=/mysql/mysql_install/mysql-5.7.25-linux-glibc2.12-x86_64/share --daemonize --pid-file=/mysql/mysql_data/mysqld.pid $MYSQLD_OPTS
# Use this to switch malloc implementation
EnvironmentFile=-/etc/sysconfig/mysql
# Sets open_files_limit
LimitNOFILE = infinity
Restart=on-failure
RestartPreventExitStatus=1
PrivateTmp=false
[root@localhost system]#
警告：上述文件内容在损坏后被手动重建。
以下是警报日志文件，显示 mysqld 已准备好连接。
2019-03-27T11:28:13.334048Z 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2019-03-27T11:28:13.335294Z 0 [Note] /mysql/mysql_install/mysql-5.7.25-linux-glibc2.12-x86_64/bin/mysqld (mysqld 5.7.25) starting as process 9309 ...
2019-03-27T11:28:13.337926Z 0 [Note] InnoDB: PUNCH HOLE support available
2019-03-27T11:28:13.337953Z 0 [Note] InnoDB: Mutexes and rw_locks use GCC atomic builtins
2019-03-27T11:28:13.337959Z 0 [Note] InnoDB: Uses event mutexes
2019-03-27T11:28:13.337964Z 0 [Note] InnoDB: GCC builtin __sync_synchronize() is used for memory barrier
2019-03-27T11:28:13.337969Z 0 [Note] InnoDB: Compressed tables use zlib 1.2.11
2019-03-27T11:28:13.337974Z 0 [Note] InnoDB: Using Linux native AIO
2019-03-27T11:28:13.338216Z 0 [Note] InnoDB: Number of pools: 1
2019-03-27T11:28:13.338317Z 0 [Note] InnoDB: Using CPU crc32 instructions
2019-03-27T11:28:13.339746Z 0 [Note] InnoDB: Initializing buffer pool, total size = 128M, instances = 1, chunk size = 128M
2019-03-27T11:28:13.351813Z 0 [Note] InnoDB: Completed initialization of buffer pool
2019-03-27T11:28:13.353463Z 0 [Note] InnoDB: If the mysqld execution user is authorized, page cleaner thread priority can be changed. See the man page of setpriority().
2019-03-27T11:28:13.365875Z 0 [Note] InnoDB: Highest supported file format is Barracuda.
2019-03-27T11:28:13.380701Z 0 [Note] InnoDB: Creating shared tablespace for temporary tables
2019-03-27T11:28:13.380772Z 0 [Note] InnoDB: Setting file './ibtmp1' size to 12 MB. Physically writing the file full; Please wait ...
2019-03-27T11:28:13.417750Z 0 [Note] InnoDB: File './ibtmp1' size is now 12 MB.
2019-03-27T11:28:13.418493Z 0 [Note] InnoDB: 96 redo rollback segment(s) found. 96 redo rollback segment(s) are active.
2019-03-27T11:28:13.418503Z 0 [Note] InnoDB: 32 non-redo rollback segment(s) are active.
2019-03-27T11:28:13.418713Z 0 [Note] InnoDB: Waiting for purge to start
2019-03-27T11:28:13.472045Z 0 [Note] InnoDB: 5.7.25 started; log sequence number 2524297
2019-03-27T11:28:13.472824Z 0 [Note] InnoDB: Loading buffer pool(s) from /mysql/mysql_data/ib_buffer_pool
2019-03-27T11:28:13.473297Z 0 [Note] Plugin 'FEDERATED' is disabled.
2019-03-27T11:28:13.474439Z 0 [Note] InnoDB: Buffer pool(s) load completed at 190327 16:58:13
2019-03-27T11:28:13.478030Z 0 [Warning] Failed to set up SSL because of the following SSL library error: SSL context is not usable without certificate and private key
2019-03-27T11:28:13.478659Z 0 [Note] Server hostname (bind-address): '*'; port: 3306
2019-03-27T11:28:13.478711Z 0 [Note] IPv6 is available.
2019-03-27T11:28:13.478724Z 0 [Note] - '::' resolves to '::';
2019-03-27T11:28:13.478745Z 0 [Note] Server socket created on IP: '::'.
2019-03-27T11:28:13.489601Z 0 [Note] Event Scheduler: Loaded 0 events
2019-03-27T11:28:13.489791Z 0 [Note] **/mysql/mysql_install/mysql-5.7.25-linux-glibc2.12-x86_64/bin/mysqld: ready for connections.**
Version: '5.7.25' socket: '/mysql/mysql_data/mysql.sock' port: 3306 MySQL Community Server (GPL)
我已经尝试过两次相同的程序，但遇到同样的问题。显示systemctl status mysqld.service“正在激活（启动）”并且不返回提示。我可以登录数据库。
答案1
从你的输出：
ExecStart=...mysqld ...--pid-file=/mysql/mysql_data/mysqld.pid...
...与您要求 systemd 监视的内容不匹配：
PID文件=/usr/local/mysql/data/mysqld.pid
纠正这两者之一，你的状态就会好得多。