MySQL安装mysqld服务The server quit without updating PID file错误解决方法

在CentOS上安装MySQL5.7，在配置service mysqld status时报错:

root@centos mysql]# service mysqld start
Starting MySQL. ERROR! The server quit without updating PID file (/var/lib/mysql/).

试了很多方法，最后用这个方法搞定了

 编辑/etc//mysqld，找到 'start' 模块，添加 --user=root 到 mysqld_safe 的参数即可
 
 case "$mode" in
  'start')
    # Start daemon

    # Safeguard (relative paths, core dumps..)
    cd $basedir

    echo $echo_n "Starting MySQL"
    if test -x $bindir/mysqld_safe
    then
      # Give extra arguments to mysqld with the file. This script
      # may be overwritten at next upgrade.
      $bindir/mysqld_safe --user=root --datadir="$datadir" --pid-file="$mysqld_pid_file_path" $other_args >/dev/null &
      wait_for_pid created "$!" "$mysqld_pid_file_path"; return_value=$?

      # Make lock for RedHat / SuSE
      if test -w "$lockdir"
      then
        touch "$lock_file_path"
      fi

      exit $return_value
    else
      log_failure_msg "Couldn't find MySQL server ($bindir/mysqld_safe)"
    fi
    ;;