Module Open3
In: open3.rb

Open3 grants you access to stdin, stdout, and stderr when running another program. Example: 

  require "open3"
  include Open3

  stdin, stdout, stderr = popen3('nroff -man')

Open3.popen3 can also take a block which will receive stdin, stdout and stderr as parameters. This ensures stdin, stdout and stderr are closed once the block exits. Example: 

  require "open3"

  Open3.popen3('nroff -man') { |stdin, stdout, stderr| ... }

Methods

popen3  

Public Instance methods

popen3(*cmd) {|| ...}

Open stdin, stdout, and stderr streams and start external executable. Non-block form: 

  require 'open3'

  [stdin, stdout, stderr] = Open3.popen3(cmd)

Block form: 

  require 'open3'

  Open3.popen3(cmd) { |stdin, stdout, stderr| ... }

The parameter cmd is passed directly to Kernel#exec.

[Source]

# File open3.rb, line 46
  def popen3(*cmd)
    pw = IO::pipe   # pipe[0] for read, pipe[1] for write
    pr = IO::pipe
    pe = IO::pipe

    pid = fork{
      # child
      fork{
        # grandchild
        pw[1].close
        STDIN.reopen(pw[0])
        pw[0].close

        pr[0].close
        STDOUT.reopen(pr[1])
        pr[1].close

        pe[0].close
        STDERR.reopen(pe[1])
        pe[1].close

        exec(*cmd)
      }
      exit!(0)
    }

    pw[0].close
    pr[1].close
    pe[1].close
    Process.waitpid(pid)
    pi = [pw[1], pr[0], pe[0]]
    pw[1].sync = true
    if defined? yield
      begin
        return yield(*pi)
      ensure
        pi.each{|p| p.close unless p.closed?}
      end
    end
    pi
  end

[Validate]

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