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PONon greedy regular expressions in Ruby: pty and expect
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copied!<p>I was doing a little test to try Ruby's pty and I can't get it right. I think the main problem is that the regular expression is non-greedy.</p> <p>This is a program called <code>inputs.rb</code>:</p> <pre class="lang-rb prettyprint-override"><code>puts "Give me root@server password:" password = gets.chomp() puts "Thank you! Your password is: #{password}" </code></pre> <p>And this is a program called <code>test.rb</code>:</p> <pre class="lang-ruby prettyprint-override"><code>require 'pty' require 'expect' #$expect_verbose = true #answer = %r/Thank you! Your password is: \w+/ PTY.spawn("ruby ./inputs.rb") do |reader, writer, pid| writer.sync = true reader.expect(/root@server password:/) do |output| writer.puts("password1234") end #reader.expect(answer) do |output| #reader.expect(/Thank you! Your password is: \w{6,}/) do |output| #reader.expect(/Thank you! Your password is: (\w+)/) do |output| reader.expect(/Thank you! Your password is: \w+/) do |output| puts "The whole output is ||||#{output}||||\n" output.first.each do |line| puts "output1 = |#{line}|\n" end end end </code></pre> <p>Unfortunately, when printing the output I get this:<br> <code>The whole output is ||||<br> password1234<br> Thank you! Your password is: p||||<br> output1 = |<br> |<br> output1 = |password1234<br> |<br> output1 = |Thank you! Your password is: p|</code></p> <p>Why is it<br> <code>Thank you! Your password is: p||||</code><br> instead of<br> <code>Thank you! Your password is: password1234||||</code> ?</p> <p>Is this normal? In case it is: is there any way to change this behaviour?</p> <p>Things that I have tried:</p> <ul> <li>The regular expression on rubular: It works.</li> <li>All the commented alternatives: None of them work (get the complete password).</li> <li><a href="http://www.42klines.com/2010/08/14/what-to-expect-from-the-ruby-expect-library.html" rel="nofollow">http://www.42klines.com/2010/08/14/what-to-expect-from-the-ruby-expect-library.html</a></li> </ul> <p>Ruby version: 1.8.7<br> Ubuntu: 10.04 (Lucid Lynx) </p> <p>I will appreciate any ideas you may have. Thank you very much.</p>

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