今天登上我那年久失修的辣鸡腾讯云服务器。然后果然数据库密码忘了，由于服务器上没一个网站，所以也找不回密码。于是一番操作之后要启动 mysql。
➜ systemctl start mysql.service
^C彻底卡住了。
重启当然试了，没有用。
参考了网页：
https://serverfault.com/questions/345951/cant-restart-mysql/345958
https://bugs.launchpad.net/ubuntu/+source/mysql-5.1/+bug/932021
https://dba.stackexchange.com/questions/119367/mysql-hangs-with-nothing-in-error-log
https://askubuntu.com/questions/455029/mysql-server-start-failed
https://forums.mysql.com/read.php?73,677115
全部没有用。
果然还是要靠自己。一番摸索找到一个日志文件“/var/log/mysqld/mysqld.log”
200310 21:01:14 mysqld_safe Logging to '/var/log/mysqld/mysqld.log'.
200310 21:01:14 mysqld_safe Starting mysqld daemon with databases from /data/mysql
2020-03-10 21:01:14 0 [Warning] TIMESTAMP with implicit DEFAULT value is deprecated. Please use --explicit_defaults_for_timestamp server option (see documentation for more details).
2020-03-10 21:01:14 0 [Note] /usr/sbin/mysqld (mysqld 5.6.47-log) starting as process 22716 ...
/usr/sbin/mysqld: File './mysql-bin.index' not found (Errcode: 13 - Permission denied)
2020-03-10 21:01:14 22716 [ERROR] Aborting
2020-03-10 21:01:14 22716 [Note] Binlog end
2020-03-10 21:01:14 22716 [Note] /usr/sbin/mysqld: Shutdown complete
200310 21:01:14 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended
关键 " File './mysql-bin.index' not found (Errcode: 13 - Permission denied)"
这么一看就好办了, 执行
touch /usr/sbin/mysql-bin.index
chown mysql /usr/sbin/mysql-bin.index问题解决.