#include <iostream>
#include <unistd.h>

using namespace std;

const int BUF_SIZE = 100;
int main() {

    string command;
    string dir;

    char current[BUF_SIZE];

    if (NULL != getcwd(current, BUF_SIZE)) {
        cout << "The current directory is " << current << endl;
    } else {
        perror("getcwd");
    }
    


    cout << "Enter a command => ";
    cin >> command;
    getline(cin,dir);
    while (command != "QUIT") {
        if (command == "UP") {
	    if (-1 == chdir("..")) {
	        perror ("chdir, can't go UP");
	    }
	} else if (command == "GO") {
	    // need to trim.
            while (isblank(dir[0]) ) {
	       dir = dir.substr(1,dir.size());
	    }
	    if (-1 == chdir(dir.c_str())) {
	        perror ("chdir");
		cerr << "Can't change to " << dir << endl;
	    }
	} else {
	   cout << "Unknown command,  " << command << endl;
	   cout << "\tUP, GO, QUIT" << endl;
	}
     
        if (NULL != getcwd(current, BUF_SIZE)) {
            cout << "The current directory is " << current << endl;
        } else {
            perror("getcwd");
        }

        cout << "Enter a command => ";
        cin >> command;
        getline(cin,dir);
    }

    return 0;
}