python - Why is this code behaving differently across various distros/Unixes? -

the following (a small c program , python script calls it) behave differently across various unixes.

in of them (e.g. debian stable), c app gets signal, message printed fine signal handler , script finishes. in others (e.g. 2 year-old ubuntu , openbsd) signal lost, , therefore message not printed @ all, , script waits forever...

the signal delivered, if in python script, change this...

mysub=subprocess.popen("./cryinabort", shell=true) 

into this...

mysub=subprocess.popen("./cryinabort", shell=false) 

so appears in unixes intermediate shell "eats" sigint, while in others forwards child process (the c program).

i took care call re-entrant functions in signal handler doesn't seem related c code - looks if signal handling behavior within "/bin/sh" (the default shell used python spawn things) not "stable" across unixes...

am doing wrong?

edit: in case wondering why used "shell=true": it's because in real code, not passing "./executable" - using shell code loops , wildcards.

this c code prints , dies when gets sigint:

#include <signal.h> #include <unistd.h>  void my_handler() {     static const char msg[] = "goodbye - test ok.\n";     write(1,msg,sizeof(msg));     fsync(1);     _exit (0); }  int main() {     (void) signal (sigint, my_handler);     while (1); } 

and python script tests sending sigint:

#!/usr/bin/env python import subprocess,signal,time mysub=subprocess.popen("./cryinabort", shell=true) time.sleep(2) mysub.send_signal(signal.sigint) mysub.wait() 

just because python uses /bin/sh doesn't mean it's same shell on systems.

/bin/sh alias in form of symbolic link: real shell busybox, bash, ash, csh, ksh, dash, zsh, tcsh, or crazy(er).

confirm you're using same shell on systems, if problem specific shell know more information on it's behavior.