ahoward/systemu

NAME

  systemu

SYNOPSIS

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

URIS

  http://github.com/ahoward/systemu
  http://rubyforge.org/projects/codeforpeople/

INSTALL

  gem install systemu

HISTORY
  2.0.0
    - versioning issue.  new gem release.

  1.3.1
    - updates for ruby 1.9.1

  1.3.0
    - move to github

  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 50931 exit 0>, "2011-12-11 22:07:30 -0700\n", "2011-12-11 22:07:30 -0700\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 50936 exit 0>, "2011-12-11 22:07:30 -0700\n", "2011-12-11 22:07:30 -0700\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/var/folders/sp/nwtflj890qnb6z4b53dqxvlw0000gp/T


  <========< 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 50956 SIGKILL (signal 9)>
    "1323666451\n1323666452\n1323666453\n"