Module Open3
In: lib/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 lib/open3.rb, line 46
46:   def popen3(*cmd)
47:     pw = IO::pipe   # pipe[0] for read, pipe[1] for write
48:     pr = IO::pipe
49:     pe = IO::pipe
50: 
51:     pid = fork{
52:       # child
53:       fork{
54:         # grandchild
55:         pw[1].close
56:         STDIN.reopen(pw[0])
57:         pw[0].close
58: 
59:         pr[0].close
60:         STDOUT.reopen(pr[1])
61:         pr[1].close
62: 
63:         pe[0].close
64:         STDERR.reopen(pe[1])
65:         pe[1].close
66: 
67:         exec(*cmd)
68:       }
69:       exit!(0)
70:     }
71: 
72:     pw[0].close
73:     pr[1].close
74:     pe[1].close
75:     Process.waitpid(pid)
76:     pi = [pw[1], pr[0], pe[0]]
77:     pw[1].sync = true
78:     if defined? yield
79:       begin
80:         return yield(*pi)
81:       ensure
82:         pi.each{|p| p.close unless p.closed?}
83:       end
84:     end
85:     pi
86:   end

[Validate]