NAME

systemu

SYNOPSIS

univeral capture of stdout and stderr and handling of child process pid for windows, *nix, etc.

URIS

http://rubyforge.org/projects/codeforpeople/
http://codeforpeople.com/lib/ruby/
http://codeforpeople.rubyforge.org/svn/

INSTALL

gem install systemu

HISTORY

1.2.0

  - fixed handling of background thread management - needed
    Thread.current.abort_on_exception = true

  - fixed reporting of child pid, it was reported as the parent's pid before

SAMPLES

<========< samples/a.rb >========>

~ > cat samples/a.rb

  #
  # systemu can be used on any platform to return status, stdout, and stderr of
  # any command.  unlike other methods like open3/popen4 there is zero danger of
  # full pipes or threading issues hanging your process or subprocess.
  #
    require 'systemu'

    date = %q( ruby -e"  t = Time.now; STDOUT.puts t; STDERR.puts t  " )

    status, stdout, stderr = systemu date
    p [ status, stdout, stderr ]

~ > ruby samples/a.rb

  [#<Process::Status: pid=987,exited(0)>, "Thu Dec 06 16:01:59 -0700 2007\n", "Thu Dec 06 16:01:59 -0700 2007\n"]

<========< samples/b.rb >========>

~ > cat samples/b.rb

  #
  # quite a few keys can be passed to the command to alter it's behaviour.  if
  # either stdout or stderr is supplied those objects should respond_to? '<<'
  # and only status will be returned
  #
    require 'systemu'

    date = %q( ruby -e"  t = Time.now; STDOUT.puts t; STDERR.puts t  " )

    stdout, stderr = '', ''
    status = systemu date, 'stdout' => stdout, 'stderr' => stderr
    p [ status, stdout, stderr ]

~ > ruby samples/b.rb

  [#<Process::Status: pid=992,exited(0)>, "Thu Dec 06 16:01:59 -0700 2007\n", "Thu Dec 06 16:01:59 -0700 2007\n"]

<========< samples/c.rb >========>

~ > cat samples/c.rb

  #
  # of course stdin can be supplied too.  synonyms for 'stdin' include '0' and
  # 0.  the other stdio streams have similar shortcuts
  #
    require 'systemu'

    cat = %q( ruby -e"  ARGF.each{|line| puts line}  " )

    status = systemu cat, 0=>'the stdin for cat', 1=>stdout=''
    puts stdout

~ > ruby samples/c.rb

  the stdin for cat

<========< samples/d.rb >========>

~ > cat samples/d.rb

  #
  # the cwd can be supplied
  #
    require 'systemu'
    require 'tmpdir'

    pwd = %q( ruby -e"  STDERR.puts Dir.pwd  " )

    status = systemu pwd, 2=>(stderr=''), :cwd=>Dir.tmpdir
    puts stderr

~ > ruby samples/d.rb

  /private/tmp

<========< samples/e.rb >========>

~ > cat samples/e.rb

  #
  # any environment vars specified are merged into the child's environment
  #
    require 'systemu'

    env = %q( ruby -r yaml -e"  puts ENV[ 'answer' ] " )

    status = systemu env, 1=>stdout='', 'env'=>{ 'answer' => 0b101010 }
    puts stdout

~ > ruby samples/e.rb

  42

<========< samples/f.rb >========>

~ > cat samples/f.rb

  #
  # if a block is specified then it is passed the child pid and run in a
  # background thread.  note that this thread will __not__ be blocked during the
  # execution of the command so it may do useful work such as killing the child
  # if execution time passes a certain threshold
  #
    require 'systemu'

    looper = %q( ruby -e" loop{ STDERR.puts Time.now.to_i; sleep 1 } " )

    status, stdout, stderr =
      systemu looper do |cid|
        sleep 3
        Process.kill 9, cid
      end

    p status
    p stderr

~ > ruby samples/f.rb

  #<Process::Status: pid=1012,signaled(SIGKILL=9)>
  "1196982119\n1196982120\n1196982121\n"