CS471/571 - Operating Systems

Displaying ./code/System-calls/fork-exec.c

#include <stdio.h>
#include <unistd.h>
#include <sys/wait.h>
#include <fcntl.h>

/**
 * Forks a new process and execs the command: ps a u
 */

int main(void)
{
  pid_t pid = fork();

  if (pid < 0) {
    perror("fork");
    return 1;
  } else if (pid == 0) {
    // Redirect output to the file "output"
    close(STDOUT_FILENO);
    open("output", O_WRONLY | O_CREAT | O_TRUNC, 0666);

    // The child process
    execlp("ps", "ps", "a", "u", NULL);
    perror("exec");
    return 1;
  } else {
    // The parent process
    int status;
    wait(&status);
    printf("Child has exited with status = %d\n", WEXITSTATUS(status));
  }
  return 0;
}