无法通过套接字'/var/run/mysqld/mysqld.sock'（2）连接到本地MySQL服务器（错误2002）

Question

I know this is a question many times asked, but I can't seem to find any solution out of the other topics.

what I've tried:

• reinstalling mysql-server (so not the client)
• chown mysql:mysql /var/lib/mysql
• checked out my.cnf where everything seems correct
• changed bind-address to localhost

• at a certain point it seemed I had no socket file and

  sudo find / -type s | grep mysqld.sock sudo find / -type s | grep mysqld.sock doesn't give any result.

  ---

Edit

I now entered mysql_config --socket and it seems there is a socket file in place now at /var/run/mysqld/mysqld.sock

also checked apparmor_status which gave following result:

apparmor module is loaded.
14 profiles are loaded.
14 profiles are in enforce mode.
   /sbin/dhclient
   /usr/bin/evince
   /usr/bin/evince-previewer
   /usr/bin/evince-previewer//sanitized_helper
   /usr/bin/evince-thumbnailer
   /usr/bin/evince-thumbnailer//sanitized_helper
   /usr/bin/evince//sanitized_helper
   /usr/lib/NetworkManager/nm-dhcp-client.action
   /usr/lib/connman/scripts/dhclient-script
   /usr/lib/cups/backend/cups-pdf
   /usr/sbin/cups-browsed
   /usr/sbin/cupsd
   /usr/sbin/mysqld
   /usr/sbin/tcpdump
0 profiles are in complain mode.
3 processes have profiles defined.
0 processes are in enforce mode.
0 processes are in complain mode.
3 processes are unconfined but have a profile defined.
   /sbin/dhclient (1089) 
   /usr/sbin/cups-browsed (1415) 
   /usr/sbin/cupsd (16608) 

After all this /etc/init.d/mysql start still fails

settings in my.cnf

[client]
port        = 3306
socket      = /var/run/mysqld/mysqld.sock

# Here is entries for some specific programs
# The following values assume you have at least 32M ram

# This was formally known as [safe_mysqld]. Both versions are currently parsed.
[mysqld_safe]
socket      = /var/run/mysqld/mysqld.sock
nice        = 0

[mysqld]
#
# * Basic Settings
#
user        = mysql
pid-file    = /var/run/mysqld/mysqld.pid
socket      = /var/run/mysqld/mysqld.sock
port        = 3306
basedir     = /usr
datadir     = /var/lib/mysql
tmpdir      = /tmp
lc-messages-dir = /usr/share/mysql
skip-external-locking

---

I checked out /var/log/error.log and when I try # /etc/init.d/mysql start following reports show up from the log:

150528 22:58:19 [Warning] Using unique option prefix key_buffer instead of key_buffer_size is deprecated and will be removed in a future release. Please use the full name instead.
150528 22:58:19 [Warning] Using unique option prefix key_buffer instead of key_buffer_size is deprecated and will be removed in a future release. Please use the full name instead.
150528 22:58:19 [Note] /usr/sbin/mysqld (mysqld 5.5.43-0ubuntu0.14.04.1) starting as process 14608 ...
150528 22:58:19 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
150528 22:58:19 [Warning] Using unique option prefix myisam-recover instead of myisam-recover-options is deprecated and will be removed in a future release. Please use the full name instead.
150528 22:58:19 [Note] Plugin 'FEDERATED' is disabled.
/usr/sbin/mysqld: Can't find file: './mysql/plugin.frm' (errno: 13)
150528 22:58:19 [ERROR] Can't open the mysql.plugin table. Please run mysql_upgrade to create it.
150528 22:58:19 InnoDB: The InnoDB memory heap is disabled
150528 22:58:19 InnoDB: Mutexes and rw_locks use GCC atomic builtins
150528 22:58:19 InnoDB: Compressed tables use zlib 1.2.8
150528 22:58:19 InnoDB: Using Linux native AIO
150528 22:58:19 InnoDB: Initializing buffer pool, size = 128.0M
150528 22:58:19 InnoDB: Completed initialization of buffer pool
150528 22:58:19 InnoDB: highest supported file format is Barracuda.
150528 22:58:19  InnoDB: Waiting for the background threads to start
150528 22:58:20 InnoDB: 5.5.43 started; log sequence number 140421610
150528 22:58:20 [Note] Server hostname (bind-address): 'localhost'; port: 3306
150528 22:58:20 [Note]   - 'localhost' resolves to '127.0.0.1';
150528 22:58:20 [Note] Server socket created on IP: '127.0.0.1'.
150528 22:58:20 [ERROR] /usr/sbin/mysqld: Can't find file: './mysql/host.frm' (errno: 13)
150528 22:58:20 [ERROR] Fatal error: Can't open and lock privilege tables: Can't find file: './mysql/host.frm' (errno: 13)
150528 22:58:20 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended

Can someone help me out how to get it fixed without loosing my db's

Answer 1

Your mysql install is hosed:

150528 22:58:20 [ERROR] /usr/sbin/mysqld: Can't find file: './mysql/host.frm' (errno: 13)

It's not starting up in the first place, hence not having a socket file. You're missing data from the internal/core mysql database, which is a very bad sign.

Answer 2

If you haven't initialized the data directory, now is the time to initialize it before starting mysqld .

You can run either of these 2 scripts provided by mysql. From your shell prompt run them as:

# mysql_secure_installation

or

# mysql_install_db --user=mysql \
         --basedir=<path to mysql install dir> \
         --datadir=/var/lib/mysql/data

mysql_install_db will invoke mysqld with --bootstrap and --skip-grant-tables options.

Answer 3

The mysql_install_db cmd did the trick. I have a socket again and I"m now able to login to mysql again. Thx