Executing UNIX command in Java

Question

I am having problems executing a command in Java. Here's the code I have for executing:
Process p = Runtime.getRuntime().exec(cmd);
                                        BufferedReader input = new BufferedReader(new InputStreamReader(p.getInputStream()));
     while((display = input.readLine()) != null)
                         num_1 = Double.parseDouble(display);
                         percent = (num_1 * 100) / (50000000);
                    flip = 1;
                    catch(IOException e)
                    e.printStackTrace();     
                    System.exit(1);
Now, when I run the script, I receive the following errors:
Exception occurred during event dispatching:
java.security.AccessControlException: access denied (java.io.FilePermission /Netadmin/UCDSNMP/bin/snmpdelta execute)
at java.lang.Throwable.fillInStackTrace(Native Method)
at java.lang.Throwable.fillInStackTrace(Compiled Code)
at java.lang.Throwable.<init>(Compiled Code)
at java.lang.Exception.<init>(Compiled Code)
at java.lang.RuntimeException.<init>(RuntimeException.java:47)
at java.lang.SecurityException.<init>(SecurityException.java:39)
at java.security.AccessControlException.<init>(AccessControlException.java:57)
at java.security.AccessControlContext.checkPermission(Compiled Code)
at java.security.AccessController.checkPermission(Compiled Code)
at java.lang.SecurityManager.checkPermission(Compiled Code)
at java.lang.SecurityManager.checkExec(SecurityManager.java:789)
at java.lang.Runtime.exec(Compiled Code)
at java.lang.Runtime.exec(Compiled Code)
at java.lang.Runtime.exec(Runtime.java:152)
at snmp.actionPerformed(Compiled Code)
at java.awt.Button.processActionEvent(Button.java:308)
at java.awt.Button.processEvent(Button.java:281)
at java.awt.Component.dispatchEventImpl(Compiled Code)
at java.awt.Component.dispatchEvent(Compiled Code)
at java.awt.EventQueue.dispatchEvent(Compiled Code)
at java.awt.EventDispatchThread.pumpOneEvent(Compiled Code)
at java.awt.EventDispatchThread.pumpEvents(Compiled Code)
at java.awt.EventDispatchThread.run(EventDispatchThread.java:83)
The user is entering the parameters for the UNIX command from a Java applet. Everything looks right, but I can't seem to run the file? Please help! All is appreciated.
Jason Banks
Northeastern University

Answer 1

Sorry, this is a bug that I've reported -- see Sun's response and my original report (along with how to get around the problem) shown below:
Hi Vira Van.,
The bug you have reported is a duplicate of Bug ID: 4522533.
Thank you for providing us with additional information
that can be used in the resolution of this bug.
This bug can be monitored via the the Java Developer
Connection Bug Parade at:
http://developer.java.sun.com/developer/bugParade/index.jshtml
The Java Developer Connection is a free channel that is
maintained by staff here at Sun.  Access this web page to join:
http://developer.java.sun.com/servlet/RegistrationServlet
The home page for the JDC is:
http://java.sun.com/jdc
Regards,
Girish
----------------- Original Bug Report-------------------
category : java
release : 1.4
subcategory : jar
type : bug
synopsis : signed applet: bad major version number on NN4.79 and ClassNotFound in IE5.5
description : FULL PRODUCT VERSION :
java version "1.4.0"
Java(TM) 2 Runtime Environment, Standard Edition (build 1.4.0-b92)
Java HotSpot(TM) Client VM (build 1.4.0-b92, mixed mode)
FULL OPERATING SYSTEM VERSION : Windows 98 [Version
4.10.2222]
ADDITIONAL OPERATING SYSTEMS :
BROWSERS: Netscape Navigator 4.79
        : Internet Explorer 5.5
EXTRA RELEVANT SYSTEM CONFIGURATION :
Applet failed to start in Netscape, the following error
message appeared in the Java Console:
Netscape Communications Corporation -- Java 1.1.5
Type '?' for options.
Symantec Java! ByteCode Compiler Version 210.065
Copyright (C) 1996-97 Symantec Corporation
# Applet exception: error: java.lang.ClassFormatError: Bad
major version number
java.lang.ClassFormatError: Bad major version number
  at java.lang.ClassLoader.defineClass(Compiled Code)
  at netscape.applet.AppletClassLoader.findClass(Compiled
Code)
  at netscape.applet.AppletClassLoader.loadClass1(Compiled
Code)
* at netscape.applet.AppletClassLoader.loadClass(Compiled
Code)
  at netscape.applet.AppletClassLoader.loadClass(Compiled
Code)
  at
netscape.applet.DerivedAppletFrame$LoadAppletEvent.dispatch(
Compiled Code)
  at
java.awt.EventDispatchThread$EventPump.dispatchEvents(Compil
ed Code)
  at java.awt.EventDispatchThread.run(Compiled Code)
  at
netscape.applet.DerivedAppletFrame$AppletEventDispatchThread
.run(Compiled Code)
The same applet
A DESCRIPTION OF THE PROBLEM :
Unable to run signed applet with Netscape 4.79 and IE5.5
native JVM.
REGRESSION.  Last worked in version 1.3.1
STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1.compile program and copy class files to a temp directory
2.sign the applet for Netscape as follows:
signtool -k aok -d \progra~1\netscape\users\viravan -Z
FIO.jar temp
3.sign the applet for Internet Explorer as follows:
cabarc -p n FileIO.cab FileIO*.class
setreg 1 true
makecert -sk aok -n "CN=aok" aok.cer
cert2spc aok.cer aok.spc
signcode -j javasign.dll -jp LOWX -spc aok.spc -k aok
FileIO.cab
Run the applet with the following HTML file:
<html><head><Title>Self-Signed Applet</Title>
<script>
document.layers ? parm=1 : parm=0;
</script>
<body>
This file I/O applet lets you read and write to the user's
local disk.<br>
<br>
<script>
document.writeln('<APPLET CODE = "FileIO" CODEBASE = "."
ARCHIVE = "FIO.jar" WIDTH = 10 HEIGHT = 10 NAME = "JSF">');
document.writeln('<param name="Netscape"
value="'+parm+'">');
document.writeln('<param name="cabbase"
value="FileIO.cab">');
document.writeln('</APPLET>');
</script>
</body>
</html>
EXPECTED VERSUS ACTUAL BEHAVIOR :
A frame with a textarea and some buttons should popup in the
center of the screen.
ERROR MESSAGES/STACK TRACES THAT OCCUR :
Applet signed with signtool failed to start in Netscape, the following error
message appeared in the Java Console:
Netscape Communications Corporation -- Java 1.1.5
Type '?' for options.
Symantec Java! ByteCode Compiler Version 210.065
Copyright (C) 1996-97 Symantec Corporation
# Applet exception: error: java.lang.ClassFormatError: Bad major version number
java.lang.ClassFormatError: Bad major version number
  at java.lang.ClassLoader.defineClass(Compiled Code)
  at netscape.applet.AppletClassLoader.findClass(Compiled Code)
  at netscape.applet.AppletClassLoader.loadClass1(Compiled Code)
* at netscape.applet.AppletClassLoader.loadClass(Compiled Code)
  at netscape.applet.AppletClassLoader.loadClass(Compiled Code)
  at netscape.applet.DerivedAppletFrame$LoadAppletEvent.dispatch(Compiled Code)
  at java.awt.EventDispatchThread$EventPump.dispatchEvents(Compiled Code)
  at java.awt.EventDispatchThread.run(Compiled Code)
  at netscape.applet.DerivedAppletFrame$AppletEventDispatchThread.run(Compiled
Code)
The same applet signed with signcode failed to start in Internet explorer, the
error message in the Java Console is:
Error loading class: FileIO
java.lang.NoClassDefFoundError
java.lang.ClassNotFoundException: FileIO
        at com/ms/vm/loader/URLClassLoader.loadClass
        at com/ms/vm/loader/URLClassLoader.loadClass
        at com/ms/applet/AppletPanel.securedClassLoad
        at com/ms/applet/AppletPanel.processSentEvent
        at com/ms/applet/AppletPanel.processSentEvent
        at com/ms/applet/AppletPanel.run
        at java/lang/Thread.run
This bug can be reproduced always.
---------- BEGIN SOURCE ----------
import java.io.*;
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import java.applet.*;
public class FileIO extends Applet implements ActionListener {
   public static void main(String[] args) {
      new FileIO();
      F.addWindowListener(new WindowAdapter() {
         public void windowClosing(WindowEvent e) {
            System.exit(0);
   public void init() {
      String tmp=getParameter("Netscape");
      if (tmp!=null) {
         if (tmp.equals("1")) {
            try {
netscape.security.PrivilegeManager.enablePrivilege("UniversalFileAccess");
               NS=true;
            } catch (Throwable exception) {}
      new FileIO();
      F.setResizable(false);
   public void stop() {
      F.dispose();
   public FileIO() {
      newline=System.getProperty("line.separator");
      F.setLayout(new BorderLayout(0,0));
      String line,inbuf="";
      String newline=System.getProperty("line.separator");
      text=new TextArea(inbuf,24,80,TextArea.SCROLLBARS_BOTH);
      text.setFont(new Font("Courier",Font.PLAIN,12));
      text.setBackground(Color.cyan);
      text.setForeground(Color.black);
      F.add("Center",text);
      Panel pan=new Panel();
      pan.setLayout(new FlowLayout(1,0,0));
      pan.setBackground(Color.yellow);
      TF=new TextField(40);
      TF.setFont(new Font("Courier",Font.PLAIN,12));
      pan.add(TF);
      OP=new Button("Open");
      OP.addActionListener(this);
      pan.add(OP);
      FS=new Button("Save");
      FS.addActionListener(this);
      pan.add(FS);
      SA=new Button("Save-As");
      SA.addActionListener(this);
      pan.add(SA);
      reset=new Button("Reset");
      reset.addActionListener(this);
      pan.add(reset);
      F.add("South",pan);
      F.pack();
      Dimension screen=Toolkit.getDefaultToolkit().getScreenSize();
      Dimension size=F.getSize();
      int X=(screen.width-size.width)/2;
      int Y=(screen.height-size.height)/2;
      F.setLocation(X,Y);
      F.setVisible(true);
   public void actionPerformed(ActionEvent event) {
      String tmp="";
      String O=text.getText();
      StringTokenizer tkn=new StringTokenizer(O,newline);
      int ntkn=tkn.countTokens();
      Object ev=event.getSource();
      if (ev.equals(OP)) {
         FileDialog fd=new FileDialog(F,"File to open",FileDialog.LOAD);
         fd.setFile("*.java");
         fd.show();
         tmp=fd.getDirectory();
         if (fd.getFile()==null) {text.requestFocus(); return;}
         tmp+=fd.getFile();
         TF.setText(tmp);
         try {
            if (NS)
{netscape.security.PrivilegeManager.enablePrivilege("UniversalFileRead");}
            BufferedReader reader=new BufferedReader(new FileReader(tmp));
            String line;
            String crlf="";
            tmp="";
            while ((line=reader.readLine())!=null) {
               tmp+=crlf+line;
               crlf="\n";
            reader.close();
            text.setText(tmp);
         } catch (Throwable e) {
            e.printStackTrace();
      } else if (ev.equals(FS) || ev.equals(SA)) {
         try {
            if (ev.equals(SA)) {
               FileDialog fd=new FileDialog(F,"File to save",FileDialog.SAVE);
               fd.setFile("*.java");
               fd.show();
               tmp=fd.getDirectory();
               tmp+=fd.getFile();
            } else {
               tmp=TF.getText();
            if (tmp.length()==0) {text.requestFocus(); return;}
            if (tmp.indexOf(".java")<0) tmp+=".java";
            TF.setText(tmp);
            if (NS)
{netscape.security.PrivilegeManager.enablePrivilege("UniversalFileWrite");}
            FileOutputStream fos=new FileOutputStream(tmp);
            BufferedWriter out=new BufferedWriter(new OutputStreamWriter(new
DataOutputStream(fos)));
            for (int i=0;i<ntkn;i++) out.write(tkn.nextToken()+newline);
            out.flush();
            out.close();
            if (NS)
{netscape.security.PrivilegeManager.revertPrivilege("UniversalFileWrite");}
            System.out.println(tmp+" saved");
         } catch (Throwable e) {
            e.printStackTrace();
      } else if (ev.equals(reset)) {
         text.setText("");
         TF.setText("");
      text.requestFocus();
   private String replace(String input, String srch, String repl) {
      int i=input.indexOf(srch);
      while (i>=0) {
         input=input.substring(0,i)+repl+input.substring(i+srch.length());
         i=input.indexOf(srch);
      return input;
   private Button OP,FS,SA,reset,TB;
   private boolean newLine,NS=false;
   private TextArea text;
   private TextField TF;
   private final char NL='\n';
   private String content,newline;
   private static Frame F=new Frame("FileIO");
---------- END SOURCE ----------
CUSTOMER WORKAROUND :
build the signed applet with SDK1.3.1 or make it a signed
applet that uses Java Plugin 1.4.0 (i.e., sign it with jarsigner).
workaround :
suggested_val :
cust_name : Vira Van.
dateCreated : 2002-03-24 19:52:18.4
dateEvaluated : 2002-04-01 18:48:10.858