Ruby笔记

1.数组遍历方法总结

array = (1..10).to_a 

length = array.length 
length.times do t 
print "#{array[t]} " 
end 
puts "n" 

length = array.length-1 
for i in 0..length do 
print "#{array[i]} " 
end 
puts "n" 

for i in array do 
    print "#{i} " 
end 
puts "n" 

array.each{x print x," "} 
puts "n" 

length = array.length 
i = 0 
while i< length do 
print "#{array[i]} " 
i = i+1 
end 
puts "n" 

length = array.length 
i = 0 
until i==length do 
print "#{array[i]} " 
i += 1 
end 
puts "n" 

array.each_index do i 
print "#{array[i]} " 

2.Ruby连接数据库

• mysql

  require 'mysql'  
  begin  
      db = Mysql.init  
      db.options(Mysql::SET_CHARSET_NAME, 'utf8')  
      db = Mysql.real_connect("127.0.0.1", "root", "123456", "test", 3306)  
      db.query("SET NAMES utf8")
      db.query("drop table if exists tb_test")  
      db.query("create table tb_test (id int,
      text LONGTEXT) ENGINE=MyISAM DEFAULT CHARSET=utf8")  
      db.query("insert into tb_test (id, text) values ( 
      1,'first line'),(2,'second line')")  
      printf "%d rows were inserted\n",db.affected_rows  
      rslt = db.query("select text from tb_test")  
      while row = rslt.fetch_row do  
          puts row[0]  
      end  
  rescue Mysql::Error => e  
          puts "Error code: #{e.errno}"  
          puts "Error message: #{e.error}"  
          puts "Error SQLSTATE: #{e.sqlstate}" if e.respond_to?("sqlstate")  
  ensure  
          db.close if db  
  end      

• redis

  #!/bin/ruby
  
  require 'redis'
  
  def writeToFile(file,content)
      fp = File.new(file,"a+") 
      if fp
          fp.syswrite(content)
      else
          puts "..."
      end
  end
  
  def connect(host)
      redis = Redis.new(:host => host,:port => 6379)
      redis.info.keys.each do |key|
          puts "#{key}:\t"+redis.info["#{key}"]
      end
  end
  
  connect("1.1.1.1")

• sqlite3

  require 'sqlite3'
  
  db = SQLite3::Database.new('test.db')
  
  db.execute("create table test(
                  ID integet not null,
                  Username varchar(20) null,
                  Password varchar(64) null)")
  db.execute("insert into test(ID.Username,Password) 
      values('0','admin','admin')")
  db.execute("select * from test")
  db.execute("update test set password='12345' where id=0")

3.Ruby socket

• 服务端：

  require 'socket'
  
  server = TCPServer.open('0.0.0.0', 8080)
  loop do
      Thread.start(server.accept) do |client|
          begin
              while true
                  puts "#{client.to_i} online"
                  data = client.read()
                  throw "empty" if data.empty?
                  #puts data.length
                  puts data
              end
          rescue Exception => e
              puts "#{client.to_i} offline"
          end
      end
  end

• 客户端：

  require 'socket'
  
  hostname = '127.0.0.1'
  port = 8080
  buf = 'test'
  s = TCPSocket.open(hostname, port)
  s.write buf
  sleep(1)
  s.close

4.ruby gem 文档服务

rubygems.org上的gem文档访问起来太慢了，其实gem本身就自带doc的功能
安装gem的时候会默认安装相应gem的doc，如果不想占用空间安装doc，则gem install XXX –no-doc 即可。
使用下列命令可以启动gem自带的文档：

gem server --port 1234

然后访问http://localhost:1234就可以查看相关的gem文档。

5.ruby改变控制台输出内容的颜色

puts "\033[1m前景色\033[0m\n"  
puts "   \033[30mBlack (30)\033[0m\n"  
puts "   \033[31mRed (31)\033[0m\n"  
puts "   \033[32mGreen (32)\033[0m\n"  
puts "   \033[33mYellow (33)\033[0m\n"  
puts "   \033[34mBlue (34)\033[0m\n"  
puts "   \033[35mMagenta (35)\033[0m\n"  
puts "   \033[36mCyan (36)\033[0m\n"  
puts "   \033[37mWhite (37)\033[0m\n"  
puts ''   
puts "\033[1m背景色\033[0m\n"  
puts "   \033[40m\033[37mBlack (40), White Text\033[0m\n"  
puts "   \033[41mRed (41)\033[0m\n"  
puts "   \033[42mGreen (42)\033[0m\n"  
puts "   \033[43mYellow (43)\033[0m\n"  
puts "   \033[44mBlue (44)\033[0m\n"  
puts "   \033[45mMagenta (45)\033[0m\n"  
puts "   \033[46mCyan (46)\033[0m\n"  
puts "   \033[47mWhite (47)\033[0m\n"  
puts ''  
puts "\033[1m其他\033[0m\n"  
puts "   Reset (0)"  
puts "   \033[1mBold (1)\033[0m\n"  
puts "   \033[4mUnderlined (4)\033[0m\n"  

6.一些比较特别的包

Ruby json gem
https://rubygems.global.ssl.fastly.net/gems/json-1.8.3.gem
树莓派wiringpi gpio包
http://pi.gadgetoid.com/article/wiringpi-as-a-ruby-gem

7.安装rvm的正确姿势

参考自:http://rvm.io/rvm/install
首先添加gpg公钥:

gpg --keyserver hkp://keys.gnupg.net --recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3

安装稳定版本的rvm

curl -sSL https://get.rvm.io | bash -s stable --ruby

8.解决kali2.0中RVM不能编译ruby-2.3.3

• 错误详情：

  ruby-2.3.3 - #compiling.......................................................................-
  Error running '__rvm_make -j4',
  showing last 15 lines of /usr/local/rvm/log/1488041042_ruby-2.3.3/make.log
  exts.mk:210: recipe for target 'ext/openssl/all' failed
  make[1]: *** [ext/openssl/all] Error 2
  make[1]: *** Waiting for unfinished jobs....
  installing default nkf libraries
  compiling objspace_dump.c
  linking shared-object json/ext/generator.so
  make[2]: Leaving directory '/usr/local/rvm/src/ruby-2.3.3/ext/json/generator'
  linking shared-object objspace.so
  make[2]: Leaving directory '/usr/local/rvm/src/ruby-2.3.3/ext/objspace'
  linking shared-object nkf.so
  make[2]: Leaving directory '/usr/local/rvm/src/ruby-2.3.3/ext/nkf'
  make[1]: Leaving directory '/usr/local/rvm/src/ruby-2.3.3'
  uncommon.mk:203: recipe for target 'build-ext' failed
  make: *** [build-ext] Error 2
  ++ return 2
  There has been an error while running make. Halting the installation.

查看/usr/local/rvm/log/1488041042_ruby-2.3.3/make.log发现是openssl版本过老导致的。

• 解决：
  第一步：先安装用于rvm的openssl：

  rvm pkg install openssl

第二步：编译安装ruby，指定openssl目录（我的是/usr/local/rvm/usr/）

rvm install ruby-2.3.3 --with-openssl-dir=/usr/local/rvm/usr/

9.设置Gems默认源为ruby-china

现在没有淘宝源了，只有ruby-china源

gem sources --add https://gems.ruby-china.org/ --remove https://rubygems.org/

设置Bundler默认源为ruby-china：

bundle config mirror.https://rubygems.org https://gems.ruby-china.org

这样修改以后，即使Gemfile中指定了Source，也会用国内的源。