一、新建文件
    f=File.new(File.join("C:","Test.txt"), "w+")
    f.puts("I am Jack")
    f.puts("Hello World")

文件模式

"r" ：Read-only. Starts at beginning of file (default mode).

"r+" ：Read-write. Starts at beginning of file.

"w" ：Write-only. Truncates existing file to zero length or creates a new file for writing.

"w+" ：Read-write. Truncates existing file to zero length or creates a new file for reading and writing.

"a" ：Write-only. Starts at end of file if file exists; otherwise, creates a new file for writing.

"a+" ：Read-write. Starts at end of file if file exists; otherwise, creates a new file for reading and writing.

"b" ：(DOS/Windows only.) Binary file mode. May appear with any of the key letters listed above

二、读取文件
    file=File.open(File.join("C:","Test.txt"),"r")
    file.each { |line| print "#{file.lineno}.", line }
    file.close

三、新建、删除、重命名文件
    File.new( "books.txt", "w" )
    File.rename( "books.txt", "chaps.txt" )
    File.delete( "chaps.txt" )

四、目录操作
1     创建目录
    Dir.mkdir("c:/testdir")
04     #删除目录
05     Dir.rmdir("c:/testdir")
07     #查询目录里的文件
08     p Dir.entries(File.join("C:","Ruby")).join(' ')
10     #遍历目录
11     Dir.entries(File.join("C:","Ruby")).each {
          |e| puts e
    }

1、ARGV and ARGF

ARGV
    ARGV << "cnblogslink.txt"
    #The gets method is a Kernel method that gets lines from ARGV
    print while gets
    p ARGV.class

ARGF
    while line = ARGF.gets
     print line
    end

2、文件信息查询
    #文件是否存在
    p File::exists?( "cnblogslink.txt" ) # => true
    #是否是文件
    p File.file?( "cnblogslink.txt" ) # => true
    #是否是目录
    p File::directory?( "c:/ruby" ) # => true
    p File::directory?( "cnblogslink.txt" ) # => false
    #文件权限
    p File.readable?( "cnblogslink.txt" ) # => true
    p File.writable?( "cnblogslink.txt" ) # => true
    p File.executable?( "cnblogslink.txt" ) # => false
    #是否是零长度
    p File.zero?( "cnblogslink.txt" ) # => false
    #文件大小 bytes
    p File.size?( "cnblogslink.txt" ) # => 74
    p File.size( "cnblogslink.txt" ) # => 74
    #文件或文件夹
    p File::ftype( "cnblogslink.txt" ) # => "file"
    #文件创建、修改、最后一次存取时间
    p File::ctime( "cnblogslink.txt" ) # => Sat Sep 19 08:05:07 +0800 2009
    p File::mtime( "cnblogslink.txt" ) # => Sat Sep 19 08:06:34 +0800 2009
    p File::atime( "cnblogslink.txt" ) # => Sat Sep 19 08:05:07 +0800 2009

3、查找文件
    puts "查找目录下所有文件及文件夹"
    Dir["c:/ruby/*"].each {|x|
          puts x
    }
    puts "条件查询"
    Dir.foreach('c:/ruby') {
        |x| puts x if x != "." && x != ".."
    }
    puts "查找某一类型文件"
    Dir["*.rb"].each {|x|
      puts x
     }
    puts "Open 查询"
    Dir.open('c:/ruby') { |d| d.grep /l/ }.each{|x| puts x}
    puts "---------------------------"      
    puts "正则表达式查询"
    Dir["c:/ruby/ruby/[rs]*"].each{|x| puts x}
    puts "------------------------"
    Dir["c:/ruby/[^s]*"].each{|x| puts x}
    puts "------------------------"    
    Dir["c:/ruby/{ruby,li}*"].each{|x| puts x}
    puts "------------------------"    
    Dir["c:/ruby/?b*"].each{|x| puts x}        
    puts "查找目录及子目录的文件"
    require 'find'     
    Find.find('./') { |path| puts path }

3、查询目录及子目录文件
    require "find"
Find.find("/etc/passwd", "/var/spool/lp1", ".") do |f|
  Find.prune if f == "."
  puts f
end
原型：ref.find( [ aName ]* ) {| aFileName | block }
prune：Skips the current file or directory, restarting the loop with the next entry. If the current file is a directory, that directory will not be recursively entered. Meaningful only within the block associated with Find::find.

4、文件比较 复制等
    require 'ftools'
    File.copy 'testfile', 'testfile1'  » true
    File.compare 'testfile', 'testfile1'  » true