The one comes from main() and the other three from every fork(). Notice that all three forks() are going to be executed. You might want to take a look at the ref: RETURN VALUE Upon successful completion, fork() shall return 0 to the child process and shall return the process ID of the child process … Read more
I had this snippet in my “special scripts” toolbox, but it got lost (clouds were not common back then), so I was searching for it and came up with this question, surprised to see that it’s missing, I searched more and came back here to post it: <?php ob_end_clean(); header(“Connection: close”); ignore_user_abort(); // optional ob_start(); … Read more
The use of fork and exec exemplifies the spirit of UNIX in that it provides a very simple way to start new processes. The fork call basically makes a duplicate of the current process, identical in almost every way. Not everything is copied over (for example, resource limits in some implementations) but the idea is … Read more
Cygwin has fully featured fork() on Windows. Thus if using Cygwin is acceptable for you, then the problem is solved in the case performance is not an issue. Otherwise you can take a look at how Cygwin implements fork(). From a quite old Cygwin’s architecture doc: 5.6. Process Creation The fork call in Cygwin is … Read more
You can use shared memory (shm_open(), shm_unlink(), mmap(), etc.). #include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #include <sys/types.h> #include <sys/wait.h> #include <unistd.h> static int *glob_var; int main(void) { glob_var = mmap(NULL, sizeof *glob_var, PROT_READ | PROT_WRITE, MAP_SHARED | MAP_ANONYMOUS, -1, 0); *glob_var = 1; if (fork() == 0) { *glob_var = 5; exit(EXIT_SUCCESS); } else { … Read more
There are two approaches: shmget and mmap. I’ll talk about mmap, since it’s more modern and flexible, but you can take a look at man shmget (or this tutorial) if you’d rather use the old-style tools. The mmap() function can be used to allocate memory buffers with highly customizable parameters to control access and permissions, … Read more
Child can ask kernel to deliver SIGHUP (or other signal) when parent dies by specifying option PR_SET_PDEATHSIG in prctl() syscall like this: prctl(PR_SET_PDEATHSIG, SIGHUP); See man 2 prctl for details. Edit: This is Linux-only
I note that <system.h> is a non-standard header; I replaced it with <unistd.h> and the code compiled cleanly. When the output of your program is going to a terminal (screen), it is line buffered. When the output of your program goes to a pipe, it is fully buffered. You can control the buffering mode by … Read more
Before asking questions here, please try it on your own and post what you have tried so far so we can guide you in the right direction. Also, it would be nice if you put more effort in asking better question. But to give you some guidance: you can create child process by using fork. … Read more
The immediate problem is that your child has an infinite loop, reading num1 over and over forever (or, rather, reading it twice and then blocking forever on a third input that will never come) before doing anything. Fix that by moving more of the code into the while loop, like this: def child(pipein): while True: … Read more