MySQL 无法启动 - 错误 : su: warning: cannot change directory to/nonexistent: No such file or directory

Question

开发和自学的新手(感谢 Covid)所以这可能很草率:(对不起...
让我首先说我不关心数据库中的数据 - 如果删除它并重新开始更容易，我对此很好(不知道该怎么做，但我可以它)
不知道是什么导致了这个问题，但有一天 MySQL 无法启动。使用服务 MySQL Restart 修复了它......两天后它再次发生此错误

sarcasticsnark@LB-HP-LT:~/Projects/FMS$ sudo service mysql start
 * Starting MySQL database server mysqld
su: warning: cannot change directory to /nonexistent: No such file or directory

我尝试了一些“解决方案”

我试过重新启动 MySQL

我给了自己对 mysql 文件的文件权限(然后试图扭转它)

我已经移动了 MySQL 目录(然后将其反转 - 因此下面是名为“mysql2”的文件夹“mysql”的副本)

我的文件现在看起来像这样，我不确定我是否获得了正确的权限。

sarcasticsnark@LB-HP-LT:/var/lib$ ls
AccountsService  command-not-found  fwupd            logrotate  mysql          mysql2,   private  systemd                  ucf                  usbutils
PackageKit       dbus               git              man-db     mysql-files    pam       python   tpm                      unattended-upgrades  vim
apt              dhcp               initramfs-tools  mecab      mysql-keyring  plymouth  snapd    ubuntu-advantage         update-manager
boltd            dpkg               landscape        misc       mysql-upgrade  polkit-1  sudo     ubuntu-release-upgrader  update-notifier
sarcasticsnark@LB-HP-LT:/var/lib$ cd mysql
sarcasticsnark@LB-HP-LT:/var/lib/mysql$ ls
'#ib_16384_0.dblwr'   TestingGround_development   binlog.000009   binlog.000013   binlog.000017   client-cert.pem   mysql.ibd            server-cert.pem   undo_002
'#ib_16384_1.dblwr'   TestingGround_test          binlog.000010   binlog.000014   binlog.index    client-key.pem    performance_schema   server-key.pem
'#innodb_temp'        auto.cnf                    binlog.000011   binlog.000015   ca-key.pem      debian-5.7.flag   private_key.pem      sys
 FMS_development      binlog.000008               binlog.000012   binlog.000016   ca.pem          mysql             public_key.pem       undo_001

我已经重新初始化了 MySQL(当不运行数独时，它会出现以下错误)

2020-07-20T02:29:41.520132Z 0 [Warning] [MY-010139] [Server] Changed limits: max_open_files: 4096 (requested 8161)
2020-07-20T02:29:41.520141Z 0 [Warning] [MY-010142] [Server] Changed limits: table_open_cache: 1967 (requested 4000)
2020-07-20T02:29:41.520561Z 0 [System] [MY-013169] [Server] /usr/sbin/mysqld (mysqld 8.0.20-0ubuntu0.20.04.1) initializing of server in progress as process 2570
2020-07-20T02:29:41.522888Z 0 [ERROR] [MY-010457] [Server] --initialize specified but the data directory has files in it. Aborting.
2020-07-20T02:29:41.522921Z 0 [ERROR] [MY-010187] [Server] Could not open file '/var/log/mysql/error.log' for error logging: Permission denied
2020-07-20T02:29:41.523139Z 0 [ERROR] [MY-013236] [Server] The designated data directory /var/lib/mysql/ is unusable. You can remove all files that the server added to it.
2020-07-20T02:29:41.523187Z 0 [ERROR] [MY-010119] [Server] Aborting
2020-07-20T02:29:41.523313Z 0 [System] [MY-010910] [Server] /usr/sbin/mysqld: Shutdown complete (mysqld 8.0.20-0ubuntu0.20.04.1)  (Ubuntu).

/var/log/mysql - 确实存在，它的权限是:

-rw-r----- 1 mysql adm 62273 Jul 19 19:36 error.log

这是 mysql/error.log

2020-07-20T01:50:07.952988Z mysqld_safe Logging to '/var/log/mysql/error.log'.
2020-07-20T01:50:07.986416Z mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
2020-07-20T01:50:08.000603Z 0 [Warning] [MY-010139] [Server] Changed limits: max_open_files: 1024 (requested 8161)
2020-07-20T01:50:08.000610Z 0 [Warning] [MY-010142] [Server] Changed limits: table_open_cache: 431 (requested 4000)
2020-07-20T01:50:08.262922Z 0 [System] [MY-010116] [Server] /usr/sbin/mysqld (mysqld 8.0.20-0ubuntu0.20.04.1) starting as process 1608
2020-07-20T01:50:08.281623Z 1 [System] [MY-013576] [InnoDB] InnoDB initialization has started.
2020-07-20T01:50:08.322464Z 1 [ERROR] [MY-012592] [InnoDB] Operating system error number 2 in a file operation.
2020-07-20T01:50:08.322818Z 1 [ERROR] [MY-012593] [InnoDB] The error means the system cannot find the path specified.
2020-07-20T01:50:08.322947Z 1 [ERROR] [MY-012594] [InnoDB] If you are installing InnoDB, remember that you must create directories yourself, InnoDB does not create them.
2020-07-20T01:50:08.323017Z 1 [ERROR] [MY-012646] [InnoDB] File ./ibdata1: 'open' returned OS error 71. Cannot continue operation
2020-07-20T01:50:08.323105Z 1 [ERROR] [MY-012981] [InnoDB] Cannot continue operation.
2020-07-20T01:50:08.972320Z mysqld_safe mysqld from pid file /var/lib/mysql/LB-HP-LT.pid ended

以及/var/lib/mysql 的权限

sarcasticsnark@LB-HP-LT:/var/lib/mysql$ cd /var/lib
sarcasticsnark@LB-HP-LT:/var/lib$ sudo ls -l mysql
[sudo] password for sarcasticsnark: 
total 58048
-rw-r----- 1 mysql mysql   196608 Jul 19 16:34 '#ib_16384_0.dblwr'
-rw-r----- 1 mysql mysql  8585216 Jul 11 22:54 '#ib_16384_1.dblwr'
drwxr-x--- 2 mysql mysql     4096 Jul 19 16:35 '#innodb_temp'
drwxr-x--- 2 mysql mysql     4096 Jul 15 18:06  FMS_development
drwxr-x--- 2 mysql mysql     4096 Jun 20 09:04  TestingGround_development
drwxr-x--- 2 mysql mysql     4096 Jun 22 20:07  TestingGround_test
-rw-r----- 1 mysql mysql       56 Jun 10 17:43  auto.cnf
-rw-r----- 1 mysql mysql   210461 Jul 15 17:01  binlog.000008
-rw-r----- 1 mysql mysql      179 Jul 15 17:30  binlog.000009
-rw-r----- 1 mysql mysql      156 Jul 15 17:43  binlog.000010
-rw-r----- 1 mysql mysql     2798 Jul 19 15:55  binlog.000011
-rw-r----- 1 mysql mysql      179 Jul 19 15:56  binlog.000012
-rw-r----- 1 mysql mysql      179 Jul 19 16:11  binlog.000013
-rw-r----- 1 mysql mysql      179 Jul 19 16:25  binlog.000014
-rw-r----- 1 mysql mysql      179 Jul 19 16:27  binlog.000015
-rw-r----- 1 mysql mysql      179 Jul 19 16:27  binlog.000016
-rw-r----- 1 mysql mysql      179 Jul 19 16:34  binlog.000017
-rw-r----- 1 mysql mysql      160 Jul 19 16:27  binlog.index
-rw------- 1 mysql mysql     1680 Jun 10 17:43  ca-key.pem
-rw-r--r-- 1 mysql mysql     1112 Jun 10 17:43  ca.pem
-rw-r--r-- 1 mysql mysql     1112 Jun 10 17:43  client-cert.pem
-rw------- 1 mysql mysql     1680 Jun 10 17:43  client-key.pem
-rw-r--r-- 1 mysql mysql        0 Jun 12 15:54  debian-5.7.flag
drwxr-xr-x 2 mysql mysql     4096 Jun 10 17:43  mysql
-rw-r----- 1 mysql mysql 25165824 Jul 19 16:28  mysql.ibd
drwxr-x--- 2 mysql mysql     4096 Jun 10 17:43  performance_schema
-rw------- 1 mysql mysql     1680 Jun 10 17:43  private_key.pem
-rw-r--r-- 1 mysql mysql      452 Jun 10 17:43  public_key.pem
-rw-r--r-- 1 mysql mysql     1112 Jun 10 17:43  server-cert.pem
-rw------- 1 mysql mysql     1676 Jun 10 17:43  server-key.pem
drwxr-x--- 2 mysql mysql     4096 Jun 10 17:43  sys
-rw-r----- 1 mysql mysql 12582912 Jul 19 16:34  undo_001
-rw-r----- 1 mysql mysql 12582912 Jul 19 16:34  undo_002

Answer 1

mysql 用户正在寻找 主目录 ，这似乎没有被分配。
为此，您可以执行:

sudo systemctl stop mysql.service
sudo usermod -d /var/lib/mysql/ mysql
sudo systemctl start mysql.service

或者

sudo service mysql stop
sudo usermod -d /var/lib/mysql/ mysql
sudo service mysql start

Based on a response found here