title: Checking directory for file with certain extension
body: <p>I am trying to check whether a directory entered through the command line contains files with a certain file extension. For example, if I have a folder "Folder1" with another folder in it "Folder 2" and Folder2 contains several files, "test.asm", "test.vm", "test.tst". I am taking either a directory or a file through the command line like this</p>
  
  <pre><code>ruby translator.rb Folder1/Folder2
  </code></pre>
  
  <p>or</p>
  
  <pre><code>ruby translator.rb Folder1/Folder2/test.vm
  </code></pre>
  
  <p>What I'm trying to do is error checking. I already have checks for whether the input is a folder and now I need to check whether the folder actually contains a .vm file. 
  What I've done so far is this:</p>
  
  <pre><code>require 'pathname'
  
  pn = Pathname.new(ARGV[0])
  
  if ARGV.size != 1
      puts "Proper usage is: ruby vmtranslator.rb file_directory\file.vm \nOR \nruby vmtranslator.rb file_directory\ where file_directory has multiple vm files test".split("\n")
  elsif !pn.exist? &amp;&amp; !pn.directory?
      puts "Something is wrong with the file"
      puts "Either try another file or check the file extension"
  elsif pn.directory? &amp;&amp; pn.children(false).extname.include?('.vm')
      puts "this should print if Folder1 is the folder, but not if Folder2 is.."
      vm_file1 = File.open("OPEN FILES WITH .vm AS EXTENSION)
  elsif pn.exist? || pn.file?
      puts "this is right"
      vm_file = File.open(ARGV[0], "r")
      asm_file = File.new(ARGV[0].sub('.vm', '.asm'), "w")
  end
  </code></pre>
  
  <p>So what that should do is check whether there is only 1 argument first, if so, then it checks if it's a file or directory else it outputs an error, then what I'm doing is checking if it's a directory. If so, I need to check if the directory actually contains .vm files. I tried <code>pn.each_child {|f| f.extname == '.vm'}</code> but that only checks the first value before it returns true. Is there any easier way to check the whole array before returning true, other than just setting some boolean?</p>
  
  <p>Some of the code up there isn't done, I'm just asking if there is any way to check a directory for a file of a certain extension. I can't find anything with my searches so far.</p>