title: ERROR 2002 (HY000): Can't connect to local MySQL server after my.cnf update
body: <p>I'm trying to modify my <code>my.cnf</code> file in Ubuntu 12.04 to fine tune mysql. I copy pasted a file created with this tool <a href="https://tools.percona.com/wizard" rel="nofollow">https://tools.percona.com/wizard</a></p>
  
  <p>This does speed up mysql but when I try to access mysql via CLI, I get the following errors:</p>
  
  <pre><code>ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (13)
  </code></pre>
  
  <p>After I replaced my old <code>my.cnf</code> file everything works again. Here is my original file:</p>
  
  <pre><code>        #
          # The MySQL database server configuration file.
          #
          # You can copy this to one of:
          # - "/etc/mysql/my.cnf" to set global options,
          # - "~/.my.cnf" to set user-specific options.
          # 
          # One can use all long options that the program supports.
          # Run program with --help to get a list of available options and with
          # --print-defaults to see which it would actually understand and use.
          #
          # For explanations see
          # http://dev.mysql.com/doc/mysql/en/server-system-variables.html
  
          # This will be passed to all mysql clients
          # It has been reported that passwords should be enclosed with ticks/quotes
          # escpecially if they contain "#" chars...
          # Remember to edit /etc/mysql/debian.cnf when changing the socket location.
          [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
          #
          # Instead of skip-networking the default is now to listen only on
          # localhost which is more compatible and is not less secure.
          bind-address        = 127.0.0.1
          #
          # * Fine Tuning
          #
          key_buffer      = 16M
          max_allowed_packet  = 16M
          thread_stack        = 192K
          thread_cache_size       = 8
          # This replaces the startup script and checks MyISAM tables if needed
          # the first time they are touched
          myisam-recover         = BACKUP
          #max_connections        = 100
          #table_cache            = 64
          #thread_concurrency     = 10
          #
          # * Query Cache Configuration
          #
          query_cache_limit   = 1M
          query_cache_size        = 16M
          #
          # * Logging and Replication
          #
          # Both location gets rotated by the cronjob.
          # Be aware that this log type is a performance killer.
          # As of 5.1 you can enable the log at runtime!
          #general_log_file        = /var/log/mysql/mysql.log
          #general_log             = 1
          #
          # Error log - should be very few entries.
          #
          log_error = /var/log/mysql/error.log
          #
          # Here you can see queries with especially long duration
          #log_slow_queries   = /var/log/mysql/mysql-slow.log
          #long_query_time = 2
          #log-queries-not-using-indexes
          #
          # The following can be used as easy to replay backup logs or for replication.
          # note: if you are setting up a replication slave, see README.Debian about
          #       other settings you may need to change.
          #server-id      = 1
          #log_bin            = /var/log/mysql/mysql-bin.log
          expire_logs_days    = 10
          max_binlog_size         = 100M
          #binlog_do_db       = include_database_name
          #binlog_ignore_db   = include_database_name
          #
          # * InnoDB
          #
          # InnoDB is enabled by default with a 10MB datafile in /var/lib/mysql/.
          # Read the manual for more InnoDB related options. There are many!
          #
          # * Security Features
          #
          # Read the manual, too, if you want chroot!
          # chroot = /var/lib/mysql/
          #
          # For generating SSL certificates I recommend the OpenSSL GUI "tinyca".
          #
          # ssl-ca=/etc/mysql/cacert.pem
          # ssl-cert=/etc/mysql/server-cert.pem
          # ssl-key=/etc/mysql/server-key.pem
  
  
  
          [mysqldump]
          quick
          quote-names
          max_allowed_packet  = 16M
  
          [mysql]
          #no-auto-rehash # faster start of mysql but no tab completition
  
          [isamchk]
          key_buffer      = 16M
  
          #
          # * IMPORTANT: Additional settings that can override those from this file!
          #   The files must end with '.cnf', otherwise they'll be ignored.
          #
          !includedir /etc/mysql/conf.d/
  </code></pre>
  
  <p>And here is my new file, anyone able to help me out here and see why I get this error after the file update?  Thanks</p>
  
  <pre><code>    # Generated by Percona Configuration Wizard (http://tools.percona.com/) version REL5-20120208
  
      [mysql]
  
      # CLIENT #
      port                           = 3306
      socket                         = /var/lib/mysql/mysql.sock
  
      [mysqld]
  
      # GENERAL #
      user                           = mysql
      default-storage-engine         = InnoDB
      socket                         = /var/lib/mysql/mysql.sock
      pid-file                       = /var/lib/mysql/mysql.pid
  
      # MyISAM #
      key-buffer-size                = 32M
      myisam-recover                 = FORCE,BACKUP
  
      # SAFETY #
      max-allowed-packet             = 16M
      max-connect-errors             = 1000000
  
      # DATA STORAGE #
      datadir                        = /var/lib/mysql/
  
      # BINARY LOGGING #
      log-bin                        = /var/lib/mysql/mysql-bin
      expire-logs-days               = 14
      sync-binlog                    = 1
  
      # CACHES AND LIMITS #
      tmp-table-size                 = 32M
      max-heap-table-size            = 32M
      query-cache-type               = 0
      query-cache-size               = 0
      max-connections                = 500
      thread-cache-size              = 50
      open-files-limit               = 65535
      table-definition-cache         = 1024
      table-open-cache               = 2048
  
      # INNODB #
      innodb-flush-method            = O_DIRECT
      innodb-log-files-in-group      = 2
      innodb-log-file-size           = 256M
      innodb-flush-log-at-trx-commit = 1
      innodb-file-per-table          = 1
      innodb-buffer-pool-size        = 6G
  
      # LOGGING #
      log-error                      = /var/lib/mysql/mysql-error.log
      log-queries-not-using-indexes  = 1
      slow-query-log                 = 1
      slow-query-log-file            = /var/lib/mysql/mysql-slow.log
  </code></pre>