Write a C program with the parent process and a child process communicating with each other using a pipe.

Question

Write a C program with the parent process and a child process communicating with each other using a pipe. The child process will execute the shell command provided by the user via command line arguments. The result of executing this shell command is passed to the parent process using a pipe. The parent process will write the result into a file called result.txt and acknowledge the user on the screen with the shell command and the total number of bytes in the result. For simplicity, the shell command contains only the command name, no argument.

Answer 1

import java.net.*;

import java.io.*;

class AeroServer

{

public static void main(String args[])

{

Socket socket=null;

long pid=0;

try

{

ServerSocket serverSocket = new ServerSocket(80);

while (true)

{

socket = serverSocket.accept();

new AeroServerThread(socket,(++pid)%Long.MAX_VALUE).start();

} //while

}

catch(IOException ex)

{

System.out.println(" server socket exception error occurs !");

}

}

}

//==========================================================

import java.lang.Thread;

import java.net.*;

import java.io.*;

class AeroServerThread extends Thread implements Runnable

{

protected Socket socket;

protected long pid;

protected InputStream inputStream;

protected OutputStream outputStream;

public AeroServerThread(Socket socket, long pID) { this.socket = socket; pid=pID; }

protected byte[] ProcessRequest(String cmdReqStr)

{

System.out.println("server:>" + cmdReqStr);

return(cmdReqStr.getBytes());

}

public void start()

{

try

{

inputStream = socket.getInputStream();

outputStream = socket.getOutputStream();

while (true)

{

int numBytes=-1; //polls

while (numBytes<1) { numBytes = inputStream.available(); }

byte inbuff[] = new byte[numBytes];

inputStream.read(inbuff);

String cmdReqStr = new String(inbuff);

if (cmdReqStr.compareToIgnoreCase("BYE")!=0)

{

byte outbuff[] = ProcessRequest(cmdReqStr);

outputStream.write(outbuff);

}

else

{

inputStream.close();

outputStream.close();

socket.close();

break;

} //command

} //while

}//try

catch (IOException ex)

{

System.out.println("Server thread exception occurs ");

return;

}

}

}

//****************************************************************************************************//

import java.net.*;

import java.io.*;

import java.util.Scanner;

class AeroClient

{

public void Go()

{

try

{

Scanner scanner = new Scanner(System.in);

Socket socket = new Socket("127.0.0.1",80);

InputStream inputStream = socket.getInputStream();

OutputStream outputStream = socket.getOutputStream();

while (true)

{

System.out.print(" input :>");

String strbuff = scanner.nextLine();

outputStream.write(strbuff.getBytes());

int numBytes=-1;

while ( (numBytes = inputStream.available())<1) { }

byte inbuff[] = new byte[numBytes];

inputStream.read(inbuff);

System.out.println("client :>"+new String(inbuff));

if (strbuff.compareToIgnoreCase("BYE")==0) { break; }

} //while

socket.close();

} //try

catch (Exception ex)

{

}

}

public static void main(String args[])

{

new AeroClient().Go();

}

}