import java.util.*;

public class Shell

{

public static native int changeDirectory(String s);

public static void main(String[] args)

{

Scanner input = new Scanner(System.in);

String cmd;

ArrayList<String> argv;

System.loadLibrary("chdir");

while(true)

{

System.out.print("> ");

cmd = input.nextLine();

if(cmd.isEmpty())

continue;

argv = parse(cmd);

if(argv.isEmpty())

continue;

else if(shbins(argv))

continue;

shexec(argv);

}

}

public static ArrayList<String> parse(String s)

{

String ps = new String();

ArrayList<String> argv = new ArrayList<String>();

int i;

for(i = 0; i < s.length(); i++)

switch(s.charAt(i))

{

case ';':

if(argv.isEmpty())

break;

else if(shbins(argv))

{

argv.clear();

break;

}

shexec(argv);

argv.clear();

break;

case ' ':

break;

default:

for(; i < s.length() && s.charAt(i) != ' '; i++)

ps += s.charAt(i);

argv.add(ps);

ps = new String();

}

return argv;

}

public static void shexec(ArrayList<String> argv)

{

try

{

String[] cmd_arr = new String[argv.size()];

Runtime shcmd = Runtime.getRuntime();

Process shproc = shcmd.exec(argv.toArray(cmd_arr));

int pchar;

while((pchar = shproc.getInputStream().read()) > 0)

System.out.print((char) pchar);

}

catch(Exception e)

{

System.out.println(e.getMessage());

}

}

public static boolean shbins(ArrayList<String> bcmd)

{

String[] bcmds = { "exit", "chdir" };

int i;

for(i = 0; i < bcmds.length; i++)

if(bcmds[i].compareTo(bcmd.get(0)) == 0)

{

switch(i)

{

case 0:

{

Runtime shexit = Runtime.getRuntime();

shexit.exit(0);

}

case 1:

if(bcmd.size() == 1)

changeDirectory(System.getenv("HOME"));

else

{

String dir = new String();

int j;

for(j = 0; j < bcmd.size() - 1; j++)

if(j > 0)

dir += ' ' + bcmd.get(j + 1);

else

dir = bcmd.get(j + 1);

if(changeDirectory(dir) < 0)

System.err.println(dir + ": No such directory.");

}

}

return true;

}

return false;

}

}