From: Gennady Bystritsky <Gennady.Bystritsky@...>
Date: 2006-09-27T06:31:01+09:00
Subject: Re: forking processes and writing to log file

Joe Van Dyk wrote:
> On 9/26/06, Joe Van Dyk <joevandyk@gmail.com> wrote:
>> Hello,
>> 
>> So, on linux, I'm forking a new Ruby process.  I redirect stdout and
>> stderr into a file and then I execute another program via 'system'.
> 
> I should probably mention that the other program that's being executed
> is rsh, which executes a command on a different machine.

You either did not redirect stdout/stderr to a file properly, or
something you execute tries to output directly to the controlling
terminal (/dev/tty). You can disassosiate your spawned process from a
controlling terminal, just to be sure (not with 'system' though):

logfile = "my_log_file.log"
pid = fork do
  File.open(logfile, 'w') do |_io|
    $stdout.reopen(_io)
    $stderr.reopen(_io)
  end

  Process.setsess # In this scenario disassociates the controlling 
                  # terminal until another tty device is open (will
                  # become new controlling tty).

  exec "the_command_line_used_to_be_launched_by_system"  
end

Process.waitpid pid

===
Gennady.