Thread: Popen problem, program freeze

I'm not sure what you mean by "by the time I call popen, the programme freeze". popen is what starts the other application, right? I would be very surprised if you managed to lose information that way.

popen is into the main(). when the program reaches this command, it freezes. if i run ps -x i see the other application running. If i kill the other application, my program continues and the gui appears.

I would guess that just means that you're not dealing with the output correctly. pclose (for instance) is not going to force-quit the other program, merely wait for it to finish. If the other program is not going to finish, then that's a problem. If you've got the data you want, and you want the other program to stop, then you could send it a signal I suppose.

I Just want the other application run in the background. My program running and i geting the output of the background application. Is that possible? :/ And how?

Originally Posted by TuXaKoS

I Just want the other application run in the background. My program running and i geting the output of the background application. Is that possible? :/ And how?

If you want the other program to keep running and you to keep getting the output, then don't call pclose. You can continually call fgets/fscanf/whatever to read from the pipe, although those will block until output from the other program arrives.

The problem is that when i call popen the program freeze, no other command after this execute :/ Any idea why? maybe because the output stream is non-stop?

Running some tests showed that, at least on this system that I am typing on right now, buffering could be standing in your way. (I.e., the output is fully buffered, not line-buffered, so if you are relying on seeing things as soon as a \n happens, well, no. I printed out 101 short lines (each ending with \n) and didn't receive any of them until the other process closed.) That means that, if for instance, the first thing after a popen is a fgets, you may be waiting a while to see anything. You can change the buffering of a FILE* with setvbuf().

Thx my friend. Everything seems to work now setvbuf() was the solution, i changed the buffer from full to line buffer