Shell Programming and Scripting

# include       <stdio.h>

main()
{
        int child;

        child=fork();
        if (child == 0) { /* child process */
                system("ls");
                }
        else { /* parent process */
                while (wait() != child) sleep(1);
                printf("\n%d child ended\n",child);
                }
}

ls &
pid=$!
wait $pid

#include<stdio.h>
#include <sys/wait.h>
#include <string.h>
int main()
{
    pid_t child;
    child=fork();
    if (child == 0) { /* child process */
        system("sleep 5");
        return 15;
    }
    else { /* parent process */
        int child_stat;
        char cmd[128];
        while(1) {
            if (child != -1) {
                if(waitpid(child, &child_stat, WNOHANG) &&
                   WIFEXITED(child_stat)) {
                    printf("Child process exited with: %d\n", WEXITSTATUS(child_stat));
                    child=-1;
                }
            }
            printf("myShell> ");
            gets(cmd);
            if (!stricmp(cmd, "quit")) return 0;
        }
    }
}