#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#define clearBuffer() while(getchar() != '\n');

int main()
{
    pid_t pid;
    char choice;
    do
    {
        printf("Select Menu\n");
        printf("a. ls\nb. ps\nc. who\n0. exit\nEnter >> ");
        choice = getchar();
        clearBuffer();
        printf("You select : %c\n", choice);
        pid = fork();

        if(pid == 0)
        {
            switch(choice)
            {
                case 'a': execlp("/bin/ls", "ls", "-al", NULL); break;
                case 'b': execlp("/bin/ps", "ps", NULL); break;
                case 'c': execlp("/usr/bin/who", "who", NULL); break;
                case '0': break;
            }
            exit(0);
        }
        if(pid < 0)
        {
            fprintf(stderr, "Fork Failed");
            exit(EXIT_FAILURE);
        }
        printf("exec() complete\n");

    } while(choice != '0');

}