case:
sudo service mysql start
tips follow：
Starting MySQL database server mysqld
No directory, logging in with HOME=/
mkdir: cannot create directory ‘//.cache’: Permission denied
-su: 19: /etc/profile.d/wsl-integration.sh: cannot create //.cache/wslu/integration: Directory nonexistent
提示没有权限，文件目录不存在，具体原因还未去细看，以下是解决贴
1.cat /etc/passwd | grep mysql
mysql:x:111:115:MySQL Server,,,:/nonexistent:/bin/false
2.sudo usermod -d /var/lib/mysql mysql
3.cat /etc/passwd | grep mysql
root:x:1000:1000:,,,:/var/lib/mysql:/bin/bash
4.sudo service mysql start
OK
ps: 如果遇到mysql用户处于precess，
usermod: user mysql is currently used by process 82
使用 ps -ef|grep mysql 找出mysql相关的服务进程 kill掉就行了
