CYGWIN

[bgr]

i need to check something with you
what would you say this program would output (from the head, without compiling :))

#include <sys/types.h>
#include <stdio.h>

int main(){
	pid_t pid;
	pid = fork();
	if (pid == 0) {
		printf("A");
		fork();
		printf("B");
	}
	else if (pid > 0){
		wait(NULL);
		printf("C");
	}
}

continue reading if you got the answer



i'd like to know what you'll say, because that was a question on my exam.
i answered ABBC and correct answer was ABABC

but then i tested in cygwin and got ABBC and sometimes ABCB, but in linux the result was indeed ABABC

is this a bug in cygwin, or it is a legitimate behaviour? if it's not a bug, how can i prove that to my professor and get my points ? :)

[vijayan]

> but then i tested in cygwin and got ABBC and sometimes ABCB
the cygwin fork is similar to what was present in early flavors of UNIX. this behaviour is somewhat different from what posix specifies and what current UNIX implementations follow. see post #2 for details.

> but in linux the result was indeed ABABC
well, as per posix it could be either ABABC or ABCAB. on freebsd (6.3 stable) it is sometimes ABABC and some other times ABCAB. perhaps on linux it might always be ABABC (because of its non-reentrant kernel).

[Hack]

Split from this thread into its own thread