Ubuntu 16.04 上的 MySQL 问题

Question

它昨天突然坏了（无法再启动）而且我不知道如何修理它。

当我跑步时：

sudo service mysql start

它给出了这个错误：

Job for mysql.service failed because the control process exited with error 
code. See "systemctl status mysql.service" and "journalctl -xe" for details.

输出systemctl status mysql.service：

● mysql.service - MySQL Community Server
   Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)<br>
   Active: inactive (dead) (Result: exit-code) since Mon 2016-09-05 15:10:31 CEST; 43s ago<br>
  Process: 6515 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=1/FAILURE)<br>
Sep 05 15:10:31 vps310084 systemd[1]: mysql.service: Service hold-off time over, scheduling restart.<br>
Sep 05 15:10:31 vps310084 systemd[1]: Stopped MySQL Community Server.<br>
Sep 05 15:10:31 vps310084 systemd[1]: mysql.service: Start request repeated too quickly.<br>
Sep 05 15:10:31 vps310084 systemd[1]: Failed to start MySQL Community Server.<br>
Sep 05 15:10:33 vps310084 systemd[1]: mysql.service: Start request repeated too quickly.<br>
Sep 05 15:10:33 vps310084 systemd[1]: Failed to start MySQL Community Server.

输出journalctl -xe：

Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel**
--
-- Unit mysql.service has failed.
--
-- The result is failed. 
Sep 05 15:14:56 vps310084 systemd[1]: mysql.service: Unit entered failed state. 
Sep 05 15:14:56 vps310084 systemd[1]: mysql.service: Failed with result 'exit-code'.
Sep 05 15:14:56 vps310084 systemd[1]: mysql.service: Service hold-off time over, scheduling restart. 
Sep 05 15:14:56 vps310084 systemd[1]: Stopped MySQL Community Server.
-- Subject: Unit mysql.service has finished shutting down<br>
-- Defined-By: systemd
-- Support: http://lists.freedesktop.org/mailman/listinfo/systemd-devel
--
-- Unit mysql.service has finished shutting down. 
Sep 05 15:14:56 vps310084 systemd[1]: mysql.service: Start request repeated too quickly. 
Sep 05 15:14:56 vps310084 systemd[1]: Failed to start MySQL Community Server.
-- Subject: Unit mysql.service has failed
-- Defined-By: systemd
--
-- Unit mysql.service has failed.
--
-- The result is failed.

Answer 1

Mysql 的 systemctl 启动脚本无法运行此命令 /usr/share/mysql/mysql-systemd-start pre

除了使用以下 shell 代码检查你的环境之外，这没有什么用：

sanity () {
  if [ ! -r /etc/mysql/my.cnf ]; then
    echo "MySQL configuration not found at /etc/mysql/my.cnf. Please create one."
    exit 1
  fi

  if [ ! -d /var/lib/mysql ] && [ ! -L /var/lib/mysql ]; then
    echo "MySQL data dir not found at /var/lib/mysql. Please create one."
    exit 1
  fi

  if [ ! -d /var/lib/mysql/mysql ] && [ ! -L /var/lib/mysql/mysql ]; then
    echo "MySQL system database not found. Please run mysql_install_db tool."
    exit 1
  fi
}

如果您直接通过 sudo 运行它，您应该会收到其中一条错误消息，请按照其建议进行操作并重试，直到它起作用为止。

这不是一个随机损坏，这是缺少文件，请检查 root 用户以及任何可以 sudo 的用户的 bash_history。