#include <sys/types.h>
#include <sys/wait.h>
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
#include <stdlib.h>
#define SUCCESS 1
#define FAILURE 0

int parse_args( int argc, char *argv[], int *n ){
  if( argc >= 3 ){
    *n = atoi( argv[1] );
    if( n >= 0 )
        return SUCCESS;
    }
  return FAILURE;
}

int main(int argc, char *argv[]){
  pid_t childpid, waitreturn;
  int i, n, status;
  if( !parse_args( argc, argv, &n ) ){
    printf( "Usage: chainexec <number of processes> <command to execute>\n" );
    exit(EXIT_FAILURE);
  }
  for( i=0; i<n; i++ ){
    if ((childpid = fork()) == -1) {
      perror("The fork failed");
      exit(1);
    } else if (childpid == 0) {          
      /* child code */
      if (execvp(argv[2], &argv[2]) < 0) {
        perror("The exec of command failed");
        exit(1);
      }
    } else                               
      /* parent code */
      while(childpid != (waitreturn = wait(&status)))
        if ((waitreturn == -1) && (errno != EINTR))
          break;
  }
  exit(0);
}