ERROR 2002 (HY000): Can't connect to local MySQL server through socket'/var/run/mysqld/mysqld.sock' (2) on Lubuntu 20.04 LTS

Question

首先，我在我的Lubuntu 20.04 LTS系统上检查了mysql的正确安装：

(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ sudo apt install mysql-server
Reading package lists... Done
Building dependency tree       
Reading state information... Done
mysql-server is already the newest version (8.0.22-0ubuntu0.20.04.3).
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.

接下来，我尝试连接mysql： (scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ sudo mysql -u root ERROR 2002 (HY000): 无法通过套接字 '/var/run/mysqld/mysqld.sock' 连接到本地 MySQL 服务器 (2) (scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ mysql -u root ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)

当尝试通过sudo systemctl stop mysql 停止mysql 时，终端半分钟以上没有响应，但最终停止了进程。 然后，我执行sudo systemctl restart mysql，同样的等待游戏超过一分钟左右。 最后显示如下错误信息：

(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ sudo systemctl restart mysql
Job for mysql.service failed because the control process exited with error code.
See "systemctl status mysql.service" and "journalctl -xe" for details.

马上查看，上面写着：

(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ systemctl status mysql.service
● mysql.service - MySQL Community Server
     Loaded: loaded (/lib/systemd/system/mysql.service; enabled; vendor preset: enabled)
     Active: activating (start) since Sun 2020-12-06 17:46:48 CET; 30s ago
    Process: 18803 ExecStartPre=/usr/share/mysql/mysql-systemd-start pre (code=exited, status=0/SUCCESS)
   Main PID: 18811 (mysqld)
     Status: "Server startup in progress"
      Tasks: 13 (limit: 9257)
     Memory: 244.7M
     CGroup: /system.slice/mysql.service
             └─18811 /usr/sbin/mysqld

Dec 06 17:46:48 andylu-Lubuntu-PC systemd[1]: Starting MySQL Community Server...

另一个要检查的命令打印出以下内容：

(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ journalctl -xe
-- The job identifier is 7118 and the job result is done.
Dec 06 17:48:29 andylu-Lubuntu-PC systemd[1]: Starting MySQL Community Server...
-- Subject: A start job for unit mysql.service has begun execution
-- Defined-By: systemd
-- Support: http://www.ubuntu.com/support
-- 
-- A start job for unit mysql.service has begun execution.
-- 
-- The job identifier is 7118

除了在终端中使用MySQL，我已经安装了python mysqlclient，如下所示：

sudo apt install default-libmysqlclient-dev
pip install mysqlclient

现在，在我的ipython-shell 中，我尝试像这样连接到我的根mySQL-database，结果与标准bash 终端中的错误相同：

Python 3.9.0 (default, Nov 22 2020, 23:12:14) 
Type 'copyright', 'credits' or 'license' for more information
IPython 7.19.0 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import MySQLdb

In [2]: mydb = MySQLdb.connect(host='localhost', user='root', passwd='astralux13')
---------------------------------------------------------------------------
OperationalError                          Traceback (most recent call last)
<ipython-input-2-8747acd85ff9> in <module>
----> 1 mydb = MySQLdb.connect(host='localhost', user='root', passwd='astralux13')

~/.virtualenvs/scrapy_course/lib/python3.9/site-packages/MySQLdb/__init__.py in Connect(*args, **kwargs)
    128     from MySQLdb.connections import Connection
    129 
--> 130     return Connection(*args, **kwargs)
    131 
    132 

~/.virtualenvs/scrapy_course/lib/python3.9/site-packages/MySQLdb/connections.py in __init__(self, *args, **kwargs)
    183         autocommit = kwargs2.pop("autocommit", False)
    184 
--> 185         super().__init__(*args, **kwargs2)
    186         self.cursorclass = cursorclass
    187         self.encoders = {k: v for k, v in conv.items() if type(k) is not int}

OperationalError: (2002, "Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)")

似乎我无法通过此错误并且不知道该尝试其他什么了。 我打算实施以下讨论中发布的一些顶级解决方案，但无济于事：

• ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)
• error: 'Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2)' -- Missing /var/run/mysqld/mysqld.sock （sudo find / -type s 没有显示我打开的任何 mysql-sockets）

Answer 1

受this post 的启发，对我有用的是以下内容（杀死仍然打开的 mysql 进程）：

(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ ps -A|grep mysql
  13308 pts/2    00:00:31 mysqld
  19980 ?        00:00:00 mysqld
(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ sudo pkill mysql
(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ ps -A|grep mysql
  19980 ?        00:00:00 mysqld
(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ sudo pkill mysql
(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ ps -A|grep mysql
(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ ps -A|grep mysqld
(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ sudo service mysql restart

根据上述帖子，我应该通过mysql -u root -p 连接，但在我的情况下导致错误：

(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ mysql -u root -p
Enter password: 
ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

现在，使用 sudo 同时避免密码标志“-p”它终于起作用了：

(scrapy_course) andylu@andylu-Lubuntu-PC:~/Desktop/Misc_python_scripts/Scrapy_Webscraping_Course/books_crawler$ sudo mysql -u root
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 8.0.22-0ubuntu0.20.04.3 (Ubuntu)

Copyright (c) 2000, 2020, 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> 

至于在MySQL更改密码，我也尝试了一堆对我不起作用的解决方案，直到我幸运地找到了this solution。 这解决了OperationalError: (1045, "Access denied for user 'root'@'localhost' (using password: YES)")，当我想在我的 ipython shell 中登录时发生：

In [4]: mydb = MySQLdb.connect(host='localhost', user='root', passwd='blablabalbala')
---------------------------------------------------------------------------
OperationalError                          Traceback (most recent call last)
<ipython-input-4-8747acd85ff9> in <module>
----> 1 mydb = MySQLdb.connect(host='localhost', user='root', passwd='astralux13')

~/.virtualenvs/scrapy_course/lib/python3.9/site-packages/MySQLdb/__init__.py in Connect(*args, **kwargs)
    128     from MySQLdb.connections import Connection
    129 
--> 130     return Connection(*args, **kwargs)
    131 
    132 

~/.virtualenvs/scrapy_course/lib/python3.9/site-packages/MySQLdb/connections.py in __init__(self, *args, **kwargs)
    183         autocommit = kwargs2.pop("autocommit", False)
    184 
--> 185         super().__init__(*args, **kwargs2)
    186         self.cursorclass = cursorclass
    187         self.encoders = {k: v for k, v in conv.items() if type(k) is not int}

OperationalError: (1045, "Access denied for user 'root'@'localhost' (using password: YES)")

现在，一切正常，我什至可以更改密码。