Grabbing output from exec

I'm trying to write a C program that grabs command output and then i'll be passing that to another program.

I'm having an issue, I cant work out how to get the command output and store it. Below is a sample of what I have

if(fork() == 0){
   execl("/bin/ls", "ls", "-1", (char *)0);
   /* do something with the output here */
}
else{
    //*other stuff goes here*
}

so basically im wondering if there is any way i can get the output from the "execl" and pass it to some thing else (e.g. via storing it in some kind of buffer).

Suggestions would be great.

You have to create a pipe from the parent process to the child, using pipe(). Then you must redirect standard ouput (STDOUT_FILENO) and error output (STDERR_FILENO) using dup or dup2 to the pipe, and in the parent process, read from the pipe. It should work.

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define die(e) do { fprintf(stderr, "%s\n", e); exit(EXIT_FAILURE); } while (0);

int main() {
  int link[2];
  pid_t pid;
  char foo[4096];

  if (pipe(link)==-1)
    die("pipe");

  if ((pid = fork()) == -1)
    die("fork");

  if(pid == 0) {

    dup2 (link[1], STDOUT_FILENO);
    close(link[0]);
    close(link[1]);
    execl("/bin/ls", "ls", "-1", (char *)0);
    die("execl");

  } else {

    close(link[1]);
    int nbytes = read(link[0], foo, sizeof(foo));
    printf("Output: (%.*s)\n", nbytes, foo);
    wait(NULL);

  }
  return 0;
}