From: Logan Capaldo <logancapaldo@...>
Date: 2005-05-12T08:11:02+09:00
Subject: Re: Infinite loop program w/ IO.popen

On 5/11/05, Venkat Venkataraju <outofjungle@gmail.com> wrote:
> Hi All
> 
> I'm trying to write a ruby program that will constantly read a open
> pipe, line by line and then log it onto another file. but when i try to
> run this script with an & at the end, the program stops as soon as it
> starts.
> 
> here is the listing of the code. if the script is run normaly without
> any & in the end, it works.
> 
> #! /usr/bin/env ruby
> # loop.rb: infinite loop program
> 
> ostream = File.new("junk.log", "w")
> pipe = IO.popen("top");
> 
> if $0 == __FILE__
>         while true
>                 ostream.puts(pipe.readline)
>                 ostream.flush
>                 sleep(1)
>         end
> end
> 
> I know that the reason for teh termination of the code has to do
> somethign with the pipe. is this a normal behavior?
> 
> i would like to execute this code without depending on the console. is
> it possible to do so? or if not, is there any other solution?
> 
> Thanks
> Venkat
> 
> 

#! /usr/bin/env ruby
# loop.rb: infinite loop program
Process.fork do
    ostream = File.new("junk.log", "w")
    pipe = IO.popen("top");

    if $0 == __FILE__
       while true
               ostream.puts(pipe.readline)
               ostream.flush
               sleep(1)
       end
   end
end

Does this version behave better? It should exit immediately but have a
forked process doing its thing in the background with no need for an
at the shell.