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

输出：

1.白日依山尽
2.黄河入海流
3.欲穷千里目
4.更上一层楼

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" )

三、目录操作

创建目录
Dir.mkdir("c:/testdir")

#删除目录
Dir.rmdir("c:/testdir")

#查询目录里的文件
p Dir.entries(File.join("C:","Ruby")).join(' ')

#遍历目录
Dir.entries(File.join("C:","Ruby")).each {
      |e| puts e
}

输出：

"C:/studyruby"
"c:/ruby"

查看目录信息

d:\Study\rubysample>irb
irb(main):001:0> dir=Dir.open( File.join("C:","Ruby") )
=> #
irb(main):002:0> dir.path
=> "C:/Ruby"
irb(main):003:0> dir.tell
=> 0
irb(main):004:0> dir.read
=> "."
irb(main):005:0> dir.rewind
=> #
irb(main):006:0> dir.each{|e| puts e}
.
..
bin
ChangeLog.txt
doc
lib
LICENSE.txt
man
MANIFEST
misc
README.1st
ReleaseNotes.txt
ruby.ico
rubyopt.del
rubyw.ico
samples
scite
share
src
uninstall.exe
=> #
irb(main):007:0>