问连接到mysql时显示套接字错误

EN

require 'rubygems'
require 'mysql'
require 'csv'
$user_name = "root"
$pas_wrd = "password"
def mysql_connect(db_name)
begin
  db = Mysql.real_connect("localhost", "#{$user_name}", "#{$pas_wrd}", "#{db_name}")
  return db
rescue Mysql::Error => e
  puts "Error code: #{e.errno}"
  puts "Error message: #{e.error}"
  puts "Error SQLSTATE: #{e.sqlstate}" if e.respond_to?("sqlstate")
end
end 

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

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

[mysqld_safe]
socket          = /var/run/mysqld/mysqld.sock
nice            = 0

[mysqld]
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
tmpdir          = /home/presoft/Documents
skip-external-locking

ps aux | grep mysql
presoft   3823  0.0  0.0   4368   816 pts/0    S+   10:41   0:00 grep --color=auto mysql

Rather than invoking init scripts through /etc/init.d, use the service(8)
utility, e.g. service mysql start

Since the script you are attempting to invoke has been converted to an
Upstart job, you may also use the start(8) utility, e.g. start mysql
start: Job failed to start