URIS

  http://rubyforge.org/frs/?group_id=1024
  http://www.codeforpeople.com/lib/ruby/


SYNOPSIS

  open child process with handles on pid, stdin, stdout, and stderr


HISTORY

  0.2.0 :
    - added exception marshaled from child -> parent when exec fails.  thanks
      to jordan breeding for a patch (yay!) and paul brannan for this most
      excellent idea.

  0.1.0 :
    - fixed docs to correctly show return value of popen4 (pid first not last).
      thanks Stefanie Tellex <stefie10@alum.mit.edu> for catching this. 
  0.0.0 :
    - initial version


INSTALL

  ~> gem install open4


SAMPLES

  simple usage:

    jib:~/eg/ruby/open4/open4-0.2.0 > cat sample/simple.rb
    require "open4"

    pid, stdin, stdout, stderr = Open4::popen4 "sh"

    stdin.puts "echo 42.out"
    stdin.puts "echo 42.err 1>&2"
    stdin.close

    ignored, status = Process::waitpid2 pid

    puts "pid        : #{ pid }"
    puts "stdout     : #{ stdout.read.strip }"
    puts "stderr     : #{ stderr.read.strip }"
    puts "status     : #{ status.inspect }"
    puts "exitstatus : #{ status.exitstatus }"


    jib:~/eg/ruby/open4/open4-0.2.0 > ruby sample/simple.rb
    pid        : 17273
    stdout     : 42.out
    stderr     : 42.err
    status     : #<Process::Status: pid=17273,exited(0)>
    exitstatus : 0


  block form - child process is automatically waited for:


    jib:~/eg/ruby/open4/open4-0.2.0 > cat sample/block.rb
    require 'open4'

    status =
      Open4::popen4("sh") do |pid, stdin, stdout, stderr|
        stdin.puts "echo 42.out"
        stdin.puts "echo 42.err 1>&2"
        stdin.close

        puts "pid        : #{ pid }"
        puts "stdout     : #{ stdout.read.strip }"
        puts "stderr     : #{ stderr.read.strip }"
      end

        puts "status     : #{ status.inspect }"
        puts "exitstatus : #{ status.exitstatus }"


    jib:~/eg/ruby/open4/open4-0.2.0 > ruby sample/block.rb
    pid        : 17295
    stdout     : 42.out
    stderr     : 42.err
    status     : #<Process::Status: pid=17295,exited(0)>
    exitstatus : 0


  exceptions are marshaled from child to parent if fork/exec fails:


    jib:~/eg/ruby/open4/open4-0.2.0 > cat sample/exception.rb
    require "open4"
    Open4::popen4 "noexist"


    jib:~/eg/ruby/open4/open4-0.2.0 > ruby sample/exception.rb
    /dmsp/reference/ruby-1.8.1//lib/ruby/site_ruby/open4.rb:100:in `popen4': No such file or directory - noexist (Errno::ENOENT)
            from sample/exception.rb:3


AUTHOR

  ara.t.howard@noaa.gov


LICENSE

  ruby's