Attach process to new Terminal (Mac OS) - c

Question

I write a program, which should create new process (I use fork(), and next in child process call execl()) and communicate with it. Here is my server:
#include <sys/types.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <pthread.h>
int main(int argc, char *argv[]) {
pid_t process;
process = fork();
if (process == 0) {
printf("The program will be executed %s...\n\n", argv[0]);
printf("Executing %s", argv[0]);
execl("hello", "Hello, World!", NULL);
return EXIT_SUCCESS;
}
else if (process < 0) {
fprintf (stderr, "Fork failed.\n");
return EXIT_FAILURE;
}
waitpid(process, NULL, NULL);
return 0;
}
And here is my client:
#include <stdio.h>
int main(int argc, char *argv[])
{
int i=0;
printf("%s\n",argv[0]);
printf("The program was executed and got a string : ");
while(argv[++i] != NULL)
printf("%s ",argv[i]);
return 0;
}
The problem is the next: my client and server show output in the same terminal. I want them to show output in separate terminals. So, how can I do it?

Answer 1

You need to have two open terminals. The idea is to run your program in the first terminal and see the output of the client in the second terminal.
First, you need to know what is the ID of the second terminal. So in the second terminal do:
$ tty
/dev/pts/1
(note your output will be probably different because mine is a SSH connection and hence pts, yours will be /dev/tty)
And then in your child process, you tell it to use this other terminal for its output. Like this:
#include <stdio.h>
#include <fcntl.h>
int main(int argc, char *argv[]) {
int fd = open("/dev/pts/1",O_RDWR) ; // note that in your case you need to update this based on your terminal name
// duplicate the fd and overwrite the stdout value
if (fd < 0){
perror("could not open fd");
exit(0);
}
if (dup2(fd, 0) < 0 ){
perror("dup2 on stdin failed");
exit(0);
}
if (dup2(fd, 1) < 0 ){
perror("dup2 on stdout failed");
exit(0);
}
// from now on all your outputs are directed to the other terminal.
// and inputs are also come from other terminal.
}