无法通过 socket '/tmp/mysql.sock' 连接到本地 MySQL 服务器 (2)

I am trying to run mysql client on my terminal. I have installed the latest mysql gem.

 ➜  ~ git:(master) ✗ ruby -v
    ruby 1.8.7 (2010-01-10 patchlevel 249) [universal-darwin11.0]
    ➜  ~ git:(master) ✗ rails -v
    Rails 2.3.14
    ➜  ~ git:(master) ✗ which mysql
    mysql: aliased to nocorrect mysql
    ➜  ~ git:(master) ✗ which ruby
    /usr/bin/ruby
    ➜  ~ git:(master) ✗ which rails
    /usr/bin/rails
    ➜  ~ git:(master) ✗ gem list

*** LOCAL GEMS ***

actionmailer (2.3.14)
actionpack (2.3.14)
activerecord (2.3.14)
activeresource (2.3.14)
activesupport (2.3.14)
builder (2.1.2)
bundler (1.0.21)
capistrano (2.9.0)
capybara (0.3.9)
cgi_multipart_eof_fix (2.5.0)
childprocess (0.2.2)
columnize (0.3.4, 0.3.3)
cucumber (0.9.4)
cucumber-rails (0.3.2)
culerity (0.2.15)
daemons (1.1.4)
database_cleaner (0.6.7)
diff-lcs (1.1.3)
expertiza-authlogic (2.1.6.1)
fastercsv (1.5.4)
fastthread (1.0.7)
ffi (1.0.10, 1.0.9)
gdata (1.1.2)
gem_plugin (0.2.3)
gherkin (2.2.9)
highline (1.6.2)
hoptoad_notifier (2.4.11)
json (1.4.6)
json_pure (1.6.1)
linecache (0.46)
mime-types (1.16)
mongrel (1.1.5)
mysql (2.8.1)
mysql2 (0.3.7)
net-scp (1.0.4)
net-sftp (2.0.5)
net-ssh (2.2.1)
net-ssh-gateway (1.1.0)
nokogiri (1.5.0)
rack (1.1.2)
rack-test (0.6.1)
rails (2.3.14)
rake (0.9.2)
rbx-require-relative (0.0.5)
rdoc (3.11)
RedCloth (4.2.8)
rgl (0.4.0)
ruby-debug (0.10.4)
ruby-debug-base (0.10.4)
rubyzip (0.9.4)
selenium-webdriver (2.8.0, 2.7.0)
stream (0.5)
term-ansicolor (1.0.7, 1.0.6)

➜  expertiza git:(master) ✗ sudo su
Password:
sh-3.2# mysql -u root -p
Enter password: 
ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)
sh-3.2# 

我无法摆脱上述错误.我在 /Users/HPV/expertiza/tmp/sockets 中创建了一个 mysql.sock 文件.在我写的文件中，mysql.default_socket =/expertiza/tmp/sockets/mysql.sock.