Start an external application - How?

ruby-talk
1

I don't need details, just a push in the right direction.

How do you start a series of external applications from within ruby (on
windows). For example, I want to start mywebcamapp.exe and
myweatherapp.exe.

Also, is it possible to have a ruby script that will stop an external
process?

Thanks,
joe

···

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2

I don't need details, just a push in the right direction.

How do you start a series of external applications from within ruby (on
windows). For example, I want to start mywebcamapp.exe and
myweatherapp.exe.

See the docs for the Kernel#system method.

Also, is it possible to have a ruby script that will stop an external
process?

I don't know if this will work on windows, but see the docs for Process.kill

···

On Aug 5, 2006, at 10:32 AM, Joe Percival wrote:

Thanks,
joe

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3

You could try using 'system', eg:

system("yourwebcamapp.exe")

Joe Percival wrote:

···

I don't need details, just a push in the right direction.

How do you start a series of external applications from within ruby (on
windows). For example, I want to start mywebcamapp.exe and
myweatherapp.exe.

4

Joe Percival wrote:

I don't need details, just a push in the right direction.

How do you start a series of external applications from within ruby (on
windows). For example, I want to start mywebcamapp.exe and
myweatherapp.exe.

Also, is it possible to have a ruby script that will stop an external
process?

Thanks,
joe

--
Posted via http://www.ruby-forum.com/\.

Anyone more knowledgable, please correct the below:
Basically, you will either want to use Threads or multiple processes.I
don't have much experience with threads, and little more with
processes. From the pickaxe (Programming Ruby), it seems that threads
may wait for the operating system call to finish before allowing both
itself and all other threads to continue. A thread is also internal to
the currently running ruby or irb session, and as such are much more
useful executing ruby code. That being said, Threads provide alot of
neat features and such.

What you probably want is a new process.

fork do
  `my_program.exe`
end

and then if you ever want you program to wait for the termination of
all your applications running, use:

Process.waitall

Note that forking and new processes and such are many times operating
system dependent. I have no clue as to if Windows supports this (I
think it does, it may be pipes that it has more issues with).

5

David Jones wrote:

You could try using 'system', eg:

system("yourwebcamapp.exe")

system seems to want the external process to complete before continuing.
exec seems to wait for completion of the external process as well. I
need to start an external process and then go on to the next command
without waiting for the external process to complete. It would also be
nice if I could capture a handle for the external process so that I
could check status or kill it later.
BTW, I only tested operation in IRB. I'll try both commands in a script
later.
joe

···

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6

On Windows, fork in not implemented. :frowning:
For this purpose I mainly use `start "" progname.exe` (note the double quotes:
if the first parameter has quotes, it's the title of the window. That
means `start "c:\Program Files\Anything.exe" won't start the
program...) start will start program and return, so ruby can
continue...

Jano

···

On 8/11/06, ilsemanetor@gmail.com <ilsemanetor@gmail.com> wrote:

Joe Percival wrote:
> I don't need details, just a push in the right direction.
>
> How do you start a series of external applications from within ruby (on
> windows). For example, I want to start mywebcamapp.exe and
> myweatherapp.exe.
>
> Also, is it possible to have a ruby script that will stop an external
> process?
>
> Thanks,
> joe
>
> --
> Posted via http://www.ruby-forum.com/\.

Anyone more knowledgable, please correct the below:
Basically, you will either want to use Threads or multiple processes.I
don't have much experience with threads, and little more with
processes. From the pickaxe (Programming Ruby), it seems that threads
may wait for the operating system call to finish before allowing both
itself and all other threads to continue. A thread is also internal to
the currently running ruby or irb session, and as such are much more
useful executing ruby code. That being said, Threads provide alot of
neat features and such.

What you probably want is a new process.

fork do
  `my_program.exe`
end

and then if you ever want you program to wait for the termination of
all your applications running, use:

Process.waitall

Note that forking and new processes and such are many times operating
system dependent. I have no clue as to if Windows supports this (I

7

Hi,

--Romeu

-----Mensagem original-----

···

From my C time, it seems like the famous fork+exec+wait. I don't know if it's possible in ruby or in all platforms. May you can start a thread and run the system there.
De: list-bounce@example.com [mailto:list-bounce@example.com] Em nome de Joe Percival
Enviada em: quinta-feira, 10 de agosto de 2006 08:38
Para: ruby-talk ML
Assunto: Re: Start an external application - How?

David Jones wrote:

You could try using 'system', eg:

system("yourwebcamapp.exe")

system seems to want the external process to complete before continuing.
exec seems to wait for completion of the external process as well. I
need to start an external process and then go on to the next command
without waiting for the external process to complete. It would also be
nice if I could capture a handle for the external process so that I
could check status or kill it later.
BTW, I only tested operation in IRB. I'll try both commands in a script
later.
joe

--
Posted via http://www.ruby-forum.com/\.

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8

Joe Percival wrote:

David Jones wrote:

You could try using 'system', eg:

system("yourwebcamapp.exe")

system seems to want the external process to complete before continuing. exec seems to wait for completion of the external process as well. I need to start an external process and then go on to the next command without waiting for the external process to complete. It would also be nice if I could capture a handle for the external process so that I could check status or kill it later.
BTW, I only tested operation in IRB. I'll try both commands in a script later.
joe

Start up each process in a thread and when your at a port that you need to do something after the processes have completed wait for the threads to complete and continue.

9

Joe Percival wrote:

David Jones wrote:

You could try using 'system', eg:

system("yourwebcamapp.exe")

system seems to want the external process to complete before continuing.
exec seems to wait for completion of the external process as well. I
need to start an external process and then go on to the next command
without waiting for the external process to complete. It would also be
nice if I could capture a handle for the external process so that I
could check status or kill it later.

This code works for me. If you start the process in a seperate thread
the rest of the Ruby script will continue to execute. To terminate it
you need some help from the operating system by using the win32ole
library http://www.ruby-doc.org/stdlib/libdoc/win32ole/rdoc/index.html

require 'win32ole'

program = "notepad.exe"

Thread.new {system(program)}
puts "Waiting 5 seconds before terminating " + program
sleep 5

class WIN32OLE
     def to_a
         a = ; self.each{ |p| a<<p }; a
     end
end

mgmt = WIN32OLE.connect('winmgmts:\\\\.')
process = mgmt.InstancesOf("win32_process").to_a.find{ |proc|
proc.name =~ /#{program}/ }
process.Terminate

The win32ole code was copied from a Google Groups thread. Some others
here might be able to talk you through it :smiley:

···

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10

If it helps, I use the following bit of code when I need to platform-independently start an external process within my test suites. It depends on win32/process being available on Windows.

Usage is: IWATestSupport.create_process(app_to_start)

i.e. IWATestSupport.create_process('webrick.rb')

module IWATestSupport
   def self.create_process(args)
     @fork_ok = true unless @fork_ok == false
     pid = nil
     begin
       raise NotImplementedError unless @fork_ok
       unless pid = fork
         Dir.chdir args[:dir]
         exec(*args[:cmd])
       end
     rescue NotImplementedError
       @fork_ok = false
       begin
         require 'rubygems'
       rescue Exception
       end

       begin
         require 'win32/process'
       rescue LoadError
         raise "Please install win32-process to run all tests on a Win32 platform. 'gem install win32-process' or http://rubyforge.org/projects/win32utils&quot;
       end
       cwd = Dir.pwd
       Dir.chdir args[:dir]
       pid = Process.create(:app_name => args[:cmd].join(' '))
       Dir.chdir cwd
     end
     pid
   end
end

Kirk Haines

···

On Fri, 11 Aug 2006, Jan Svitok wrote:

On Windows, fork in not implemented. :frowning:
For this purpose I mainly use `start "" progname.exe` (note the double quotes:
if the first parameter has quotes, it's the title of the window. That
means `start "c:\Program Files\Anything.exe" won't start the
program...) start will start program and return, so ruby can
continue...

11

Thanks!
joe
Sard Aukary wrote:

···

This code works for me.

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