title: mysql ERROR! The server quit without updating PID file?
body: <p>My Vps mysql wont boot , when i attempt to command service mysql start i got this error</p>
  
  <pre><code>root@## [/var/lib/mysql]# service mysql start
  Starting MySQL... ERROR! The server quit without updating PID file (/var/lib/mysql/***.***.com.pid).
  </code></pre>
  
  <p>this is <code>my.cnf</code></p>
  
  <pre><code>[mysqld]
  local-infile=0
  set-variable = 100
  max_connections=100
  safe-show-database
  
  #userstat_running=on
  query_cache_limit=4M
  query_cache_size=64M
  query_cache_type=1
  max_user_connections=100
  interactive_timeout=30
  wait_timeout=100
  connect_timeout = 20
  thread_cache_size = 256
  key_buffer_size=16M
  join_buffer_size=2M
  max_heap_table_size=16M
  low_priority_updates=1
  max_allowed_packet=128M
  max_seeks_for_key=100
  record_buffer=2M
  sort_buffer_size=16M
  read_buffer_size=16M
  max_connect_errors=10
  # Try number of CPU's*2 for thread_concurrency
  thread_concurrency=4
  myisam_sort_buffer_size=64M
  tmp_table_size= 64M
  set-variable=table_cache=100
  read_rnd_buffer_size=1M
  skip-name-resolve
  
  open_files_limit=6050
  [mysqld_safe]
  
  log-error=/var/log/mysqld.log
  
  pid-file=/var/run/mysqld/mysqld.pid
  </code></pre>
  
  <p>and this is the error log</p>
  
  <pre><code>140227 21:23:41 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql
  140227 21:23:41 [Note] Plugin 'FEDERATED' is disabled.
  140227 21:23:41 InnoDB: The InnoDB memory heap is disabled
  140227 21:23:41 InnoDB: Mutexes and rw_locks use InnoDB's own implementation
  140227 21:23:41 InnoDB: Compressed tables use zlib 1.2.3
  140227 21:23:41 InnoDB: Using Linux native AIO
  140227 21:23:41 InnoDB: Initializing buffer pool, size = 128.0M
  140227 21:23:41 InnoDB: Completed initialization of buffer pool
  140227 21:23:41 InnoDB: highest supported file format is Barracuda.
  140227 21:23:41  InnoDB: Waiting for the background threads to start
  140227 21:23:42 InnoDB: 5.5.35 started; log sequence number 2155325
  140227 21:23:42 [ERROR] /usr/sbin/mysqld: unknown variable 'set-variable=100'
  140227 21:23:42 [ERROR] Aborting
  
  140227 21:23:42  InnoDB: Starting shutdown...
  140227 21:23:43  InnoDB: Shutdown completed; log sequence number 2155325
  140227 21:23:43 [Note] /usr/sbin/mysqld: Shutdown complete
  
  140227 21:23:43 mysqld_safe mysqld from pid file /var/lib/mysql/***/***.com.pid ended
  </code></pre>
  
  <p>how to fix this ? any idea </p>