From: ientu <lamola@...>
Date: 2005-10-14T00:26:53+09:00
Subject: exec and pipe

Hi All,

I have been coding-testing-googling all day long but I couldn't find a
solution for this.
I need to create a pipe between some ruby code and a perl script. The
perl script  will be the writer: the script prints on STDOUT lines of
information at a random pace.
These lines are to be processed in ruby in real time, as soon as they
enter the pipe, without waiting for the termination of the perl script.

Another requirement is that the perl script must be invoked from a ruby
class.

I have tried with the following:

readme, writeme = IO.pipe
pid = fork {
  $stdout = writeme
  readme.close
  exec('perl some_script.pl')
}
# Process.waitpid(pid,0)
# do not wait for the process to terminate
# read output in real time

writeme.close
while readme.gets do
  puts 'processing: ' + $_
  ...
end




This doesn't work, apparently when I run 'exec' STDOUT is reopened and
I get the output from the perl script on screen.

What am I doing wrong?
Is this the right approach?


Many thanks
/giulio