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