Why the child process is not executed?

It is getting executed and it should be outputting the text. No newlines should be necessary:

https://ideone.com/a1tznH

#include <stdio.h>#include <unistd.h>#include <sys/wait.h>int main() {   int n = 1;   if(fork() == 0) {      printf("child");      n = n + 1;      exit(0);   }   n = n + 2;   printf("%ld: %d\n", (long)getpid(), n); //this is how you should print pids   wait(0);   return 0;}

Example output:

child23891: 3

Perhaps you didn't notice the child text was at the beginning of your next prompt:

18188: 3child[21:17] pskocik@laptop: $

The child is executed but two processes are trying to write on the same FD - STDOUT (File Descriptor).

If you want to see the result, put "\n" in printf of the child.

int main() {   int n = 1;   if(fork() == 0)    {     printf("child\n");     n = n + 1;     exit(0);   }   n = n + 2;   printf("%d: %d\n", getpid(), n);   wait(0);   return 0;}

Try

pid_t pid;pid = fork();if(pid < 0){   printf("fail to fork");}else if (pid == 0){    printf("running child");    exit(0);}else{    print("running parent");    wait(0);    print("child done");}return 0;

This is the basic structure of a program I wrote recently which works. Not totally sure why yours didn't work though.