---- extPart_ST_10_14_03_Tuesday_November_02_2004_23267 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Hi Brian, Firstly, thanks for the help. > I don't think you said anything about the platform you are running under. > When I run your test under ruby 1.8.2p2 and FreeBSD 4.10, I get: > > $ ruby command_runner_shell_test.rb > Hello, world! 2 times! > $ > > which looks pretty good to me too. You actually need to run the test script with a shell redirection. Like in the example output I gave, I redirected output of the script to a file, output.txt, and then cat'ed it: $ ruby command_runner_shell_test.rb > output.txt $ cat output.txt Hello, world! 2 times! Hello, world! 2 times! Hello, world! 2 times! Hopefully that will reproduce the same results I am seeing? Otherwise if this problem just happens on mine... well that is just going to make it even more difficult for me to track. :( > If you are running under cygwin plus some Microsoft operating system I am running this on Debian Linux 3.1, the testing branch of the distribution. Ruby v1.8.2. Maybe the Debian package maintainers applied some patches, but I doubt that would be the cause... but maybe. > Seriously, Windows is badly broken with regard to processes and pipes. I would agree there. I once had to write a sh-like shell that compiled and ran on both Windows and Linux, for a uni project. :) I never finished the windows part by the deadline (I did start a bit last minute though)... > Why is this a problem? You can call waitpid on the child pid, and if it has > already terminated, then it will still be in the process table (as a zombie) > waiting for you to reap its exit status. That's unless someone has messed > with SIGCHLD. That is just the handy little fact I needed. Now I guess I can remove all that part of the code and be confident it works. Thanks! > And even if the process had gone completely, you'd just get an error from > waitpid saying that the child did not exist (which is fine, since you know > it did exist at the time you forked, so it must have died since then). Only > if another process on the system had forked and re-used the same PID in the > mean time would that be a problem. Which was the (unlikely) problem I was trying to protect myself from. I know it won't happen... but the fact that it "technically" could made me uncomfortable. :P I've attached the 'updated' command_runner with the threading stuff removed. Hopefully with that cruft gone, it is easier to read. Steven -- NAUTRONIX LTD Marine Technology Solutions Steven Wong Undergraduate Software Engineer Nautronix Ltd ABN 28 009 019 603 108 Marine Terrace, Fremantle, WA 6160, Australia T +61 (0)8 9431 0000, F +61 (0)8 9430 5901, http://www.nautronix.com E steven.wong / nautronix.com.au T +61 (0)8 9431 0024 M +61 (0)413 332 005 -- This email is confidential and intended solely for the use of the individual to whom it is addressed. Any views or opinions presented are solely those of the author and do not necessarily represent those of NAUTRONIX LTD. If you are not the intended recipient, you have received this email in error and use, dissemination, forwarding, printing, or copying of this email is strictly prohibited. If you have received this email in error please contact the sender. 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Please ensure that you run virus checking software on all e-mail messages and attachments before reading them. ---- extPart_ST_10_14_03_Tuesday_November_02_2004_23267 Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename="command_runner.rb" class CommandRunner attr :command attr :childPid def initialize(*command) @command ommand @childPid il @readPipe il @readErrorPipe il @writePipe il end def closeWrite @writePipe.close end def kill Process.kill("KILL", @childPid) end def read return @readPipe.read end def readError return @readErrorPipe.read end def run parent_to_child_read, parent_to_child_write O.pipe child_to_parent_read, child_to_parent_write O.pipe child_to_parent_error_read, child_to_parent_error_write O.pipe @childPid ork do parent_to_child_write.close child_to_parent_read.close child_to_parent_error_read.close $stdin.reopen(parent_to_child_read) or raise "Unable to redirect STDIN" $stdout.reopen(child_to_parent_write) or raise "Unable to redirect STDOUT" $stderr.reopen(child_to_parent_error_write) or raise "Unable to redirect STDERR" exec(*@command) end child_to_parent_write.close child_to_parent_error_write.close parent_to_child_read.close @readPipe hild_to_parent_read @readErrorPipe hild_to_parent_error_read @writePipe arent_to_child_write end #-------------------------------------------------------------------------- # Description: Waits for command to exit # Returns : The return code of the program when it exited #-------------------------------------------------------------------------- def wait if not @childPid raise "Waiting for a process that has not started" end return_value rocess.waitpid2(@childPid)[1].exitstatus @childPid il return return_value end def write(string) @writePipe.write(string) end end ---- extPart_ST_10_14_03_Tuesday_November_02_2004_23267--