Forum: Ruby on Rails [ANN] open4-0.3.0

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Ara.T.Howard (Guest)
on 2006-04-19 06:53
(Received via mailing list)
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

   0.3.0 :
     - bug fix from jordan breeding.  general clean up.  added spawn
method.

   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 T. <removed_email_address@domain.invalid> for catching 
this.
   0.0.0 :
     - initial version

INSTALL

   ~> gem install open4

SAMPLES

   ----------------------------------------------------------------------------
   simple usage
   ----------------------------------------------------------------------------

     harp: > 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 }"


     harp: > ruby sample/simple.rb
     pid        : 17273
     stdout     : 42.out
     stderr     : 42.err
     status     : #<Process::Status: pid=17273,exited(0)>
     exitstatus : 0


   ----------------------------------------------------------------------------
   in block form - the child process is automatically waited for
   ----------------------------------------------------------------------------

     harp: > 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 }"


     harp: > 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
   ----------------------------------------------------------------------------

     harp: > cat sample/exception.rb
     require "open4"
     Open4::popen4 "noexist"


     harp: > 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

   ----------------------------------------------------------------------------
   the spawn method provides and even more convenient method of running
a
   process, allowing any object that supports 'each', 'read', or 'to_s'
to be
   given as stdin and any objects that support '<<' to be given as
   stdout/stderr.  an exception is thrown if the exec'd cmd fails
(nonzero
   exitstatus) unless the option 'raise'=>false is given
   ----------------------------------------------------------------------------

     harp: > cat sample/spawn.rb
     require 'open4'
     include Open4

     cat = '  ruby -e"  ARGF.each{|line| STDOUT << line}  "  '

     stdout, stderr = '', ''
     status = spawn cat, 'stdin' => '42', 'stdout' => stdout, 'stderr'
=> stderr
     p status
     p stdout
     p stderr

     stdout, stderr = '', ''
     status = spawn cat, 0=>'42', 1=>stdout, 2=>stderr
     p status
     p stdout
     p stderr


     harp: > RUBYLIB=lib ruby sample/spawn.rb
     0
     "42"
     ""
     0
     "42"
     ""

AUTHOR

   removed_email_address@domain.invalid

LICENSE

   ruby's


enjoy.


-a
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