# Systemu-1.2.0

**URL:** <https://www.ruby-forum.com/t/systemu-1-2-0/122367>\
**Category:** Ruby\
**Created:** [December 7, 2007, 12:02am UTC](https://www.ruby-forum.com/t/systemu-1-2-0/122367 "2007-12-07T00:02:38Z")\
**Posts on this page:** 1\
**Page:** 1

<div class="post-metadata">

**Author:** ![ara.t.howard](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/a8b319/32.png) [@ara.t.howard](https://www.ruby-forum.com/u/ara.t.howard)\
**Post date:** [December 7, 2007, 12:02am UTC](https://www.ruby-forum.com/t/systemu-1-2-0/122367/1 "2007-12-07T00:02:38Z")

</div>

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://rubyforge.org/projects/codeforpeople/)  
[http://codeforpeople.com/lib/ruby/](http://codeforpeople.com/lib/ruby/)  
[http://codeforpeople.rubyforge.org/svn/](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"

```

enjoy.

a @ [http://codeforpeople.com/](http://codeforpeople.com/)