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"