简述:
今天在做LNMP环境的时候，mysql启动失败，LNMP环境是用的oneinstack一键安装脚本安装的。
报错简述:
➜ sudo systemctl restart mysqld.service
Job for mysqld.service failed because the control process exited with error code.
See "systemctl status mysqld.service" and "journalctl -xe" for details.
➜ sudo systemctl status mysqld.service
● mysqld.service - LSB: start and stop MySQL
Loaded: loaded (/etc/init.d/mysqld; generated)
Active: failed (Result: exit-code) since Tue 2018-11-06 18:31:34 CST; 6s ago
Docs: man:systemd-sysv-generator(8)
Process: 22460 ExecStart=/etc/init.d/mysqld start (code=exited, status=1/FAILURE)
11月 06 18:31:33 ubuntu-kevin systemd[1]: Starting LSB: start and stop MySQL...
11月 06 18:31:33 ubuntu-kevin mysqld[22460]: Starting MySQL
11月 06 18:31:34 ubuntu-kevin mysqld[22460]: . * The server quit without updating PID file (/tmp/mysql.pid).
11月 06 18:31:34 ubuntu-kevin systemd[1]: mysqld.service: Control process exited, code=exited status=1
11月 06 18:31:34 ubuntu-kevin systemd[1]: mysqld.service: Failed with result 'exit-code'.
11月 06 18:31:34 ubuntu-kevin systemd[1]: Failed to start LSB: start and stop MySQL.
大致意思是因为/tmp目录缺少启动文件(mysql.pid)导致的，恩，于是参照网上提供的方法，修改/etc/my.cnf文件
#socket = /tmp/mysql.sock
socket = /var/lib/mysql/mysql.sock
修改pid文件的存放目录，然后chmod -R 777 /var/lib/mysql/
重新启动，恩？失败!!
➜ sudo systemctl status mysqld.service
● mysqld.service - LSB: start and stop MySQL
Loaded: loaded (/etc/init.d/mysqld; generated)
Active: failed (Result: exit-code) since Tue 2018-11-06 18:31:34 CST; 6s ago
Docs: man:systemd-sysv-generator(8)
Process: 22460 ExecStart=/etc/init.d/mysqld start (code=exited, status=1/FAILURE)
11月 06 18:31:33 ubuntu-kevin systemd[1]: Starting LSB: start and stop MySQL...
11月 06 18:31:33 ubuntu-kevin mysqld[22460]: Starting MySQL
11月 06 18:31:34 ubuntu-kevin mysqld[22460]: . * The server quit without updating PID file (/var/lib/mysql/mysql.pid).
11月 06 18:31:34 ubuntu-kevin systemd[1]: mysqld.service: Control process exited, code=exited status=1
11月 06 18:31:34 ubuntu-kevin systemd[1]: mysqld.service: Failed with result 'exit-code'.
11月 06 18:31:34 ubuntu-kevin systemd[1]: Failed to start LSB: start and stop MySQL.
那继续,还有大佬说查看mysql报错日志
➜ vi /data/mysql/mysql-error.log
文件无法打开???权限不够?行吧,我sudo
➜ sudo vi /data/mysql/mysql-error.log
2018-11-04T11:47:38.194829Z 0 [Note] InnoDB: Buffer pool(s) dump completed at 181104 19:47:38
2018-11-04T11:47:39.352071Z 0 [Note] InnoDB: Shutdown completed; log sequence number 2592787
2018-11-04T11:47:39.353709Z 0 [Note] InnoDB: Removed temporary tablespace data file: "ibtmp1"
2018-11-04T11:47:39.353718Z 0 [Note] Shutting down plugin 'MEMORY'
2018-11-04T11:47:39.353723Z 0 [Note] Shutting down plugin 'MRG_MYISAM'
2018-11-04T11:47:39.353726Z 0 [Note] Shutting down plugin 'PERFORMANCE_SCHEMA'
2018-11-04T11:47:39.353741Z 0 [Note] Shutting down plugin 'sha256_password'
2018-11-04T11:47:39.353743Z 0 [Note] Shutting down plugin 'mysql_native_password'
2018-11-04T11:47:39.353856Z 0 [Note] Shutting down plugin 'binlog'
2018-11-04T11:47:39.465526Z 0 [Note] /usr/local/mysql/bin/mysqld: Shutdown complete
等会，好像有什么不对啊，今天明明是11-06，你这个11-04什么鬼!!!!
绝望～
然后冷静下来，想到，刚刚查看日志文件为什么会显示权限不够，什么时候vi都要超级管理员权限了。
然后ll看了一下文件的所属
drwxr-x--- 2 1002 1002 4096 11月 4 19:47 mysql
嗯哼，这个1002是什么鬼，顿时发现问题
解决方法:
创建mysql用户和mysql组
➜ sudo useradd mysql -g mysql
➜ sudo groupadd mysql
➜ chown -R mysql:mysql /usr/local/mysql
➜ chown -R mysql:mysql /var/lib/mysql
➜ chown -R mysql:mysql /data/mysql
➜ sudo systemctl restart mysqld.service
nice启动成功了！！！
➜ mysql mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 2
Server version: 5.7.24-log MySQL Community Server (GPL)
Copyright (c) 2000, 2018, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MySQL [(none)]>
MySQL [(none)]> quit
Bye
开心～～