On Tue, Feb 24, 2015 at 08:33:41PM +0100, jannik laval wrote: > Hi pharoers, > > I am playing with OSProcess. > I am using an example, and I am annoyed with a strange bug: > > Here is the code I want to execute, and does not work: > ==== > |thread process output| > myCmd := 'rostopic bw /turtle1/pose'. > thread := [process := (PipeableOSProcess command: myCmd) ] fork. > 3 second wait. > output := process upToEnd. > output inspect. > thread terminate. > ===
Hi Jannik, I am not familiar with the rostopic command, but it is common for some Unix programs to flush their output when the stdout is connected to /dev/tty (a terminal), but not necessarily if connected to a pipe or to a file. So it may be that the running rostopic program is producing output, but that the output has not yet been flushed to the pipe connected to your PipeableOSProcess. Your #upToEnd call will read the available data from the OS pipe, but it will not read data that was "written" by the rotopic program, but not yet flushed out to the OSPipe. So I am guessing that this may be why the data seems to be missing. I notice also that you are putting your PipeableOSProcess into a separate Smalltalk process using #fork. This is probably not necessary, so try getting rid of the #fork and the later thread terminate. It will not fix the problem for you, but it will simplify the code. Dave > > 'rostopic bw /turtle1/pose' is a command that is a loop displaying the > current bandwidth of a ROS process. In a terminal, it works fine. With > OSProcess the output value is empty. > > My source code is correct: if I replace myCmd by : > myCmd := 'ping localhost'. > > It is a loop too, and it returns a correct string. > > I have clearly no idea of where I have to search... Any help or discussion > about that would be great :) > > Thank you, > > Oups, some infos: > I am using Ubuntu 14.04 > Pharo3.0 with Moose 5.0, latest update: #30863 > The script I use (rostopic) is a python script (does it impact ?) > > > -- > > ~~Jannik Laval~~ > ??cole des Mines de Douai > Enseignant-chercheur > http://www.jannik-laval.eu > http://www.phratch.com > http://www.approchealpes.info > http://car.mines-douai.fr/
