Null pointer exec. in Runtime.execute()

Question

Hello,
I have a very simple shell script in /tmp directory which I want to execute, so I do
Runtime.getRuntime.execute(String "scriptname",String [] null, File "/tmp");
and it gives me nullpointer exception, any clue what I am missing...
thanks,

Answer 1

Your params to pass to the execute should look like
Runtime.getRuntime.execute("ksh -c /tmp/scriptname");
where ksh is your shell and -c is the parm to pass to execute a script.
or use this class
as
SysCommands sysc = new SysCommands();
String[] value_returned = sysc.execute(sysc.setCommand("/tmp/myscript");
import java.io.*;
import java.util.Vector;
public class SysCommands {
private static int osname = 0;
public SysCommands() {
getSystem();
public String getSystem(){
String OS = System.getProperty("os.name");
if(OS.equals("Windows 2000")){
osname = 1;
} else if(OS.equals("AIX")){
osname = 2;
} else if(OS.equals("Windows XP")){
osname = 3;
} else if(OS.equals("Linux")){
osname = 4;
} else {
osname = 0;
// Add any other OS you may need.
return OS;
public String[] setCommand(String cmd){
String[] command = new String[3];
switch(osname){
case 1:
command[0] = "cmd.exe";
command[1] = "/c";
command[2] = cmd;
break;
case 2:
command[0] = "ksh";
command[1] = "-c";
command[2] = cmd;
break;
case 3:
command[0] = "cmd.exe";
command[1] = "/c";
command[2] = cmd;
break;
case 4:
command[0] = "bash";
command[1] = "-c";
command[2] = cmd;
break;
case 0:
break;
return command;
public String[] execute(String[] command){
Vector v = new Vector();
try {
Process p2 = Runtime.getRuntime().exec(command);
BufferedReader br2 = new BufferedReader(new InputStreamReader(p2.getInputStream()));
String line = br2.readLine();
v.addElement(line);
for(int t=0; line != null; t++){
line = br2.readLine();
v.addElement(line);
br2.close();
} catch(Exception e){
// Enter your own error logging.
//Log log = new Log();
//log.createLog("Execution.err", "Error in execution." + e.getMessage() + " - " + e.toString());
int LENGTH = v.size() -1;
String[] returnArray = new String[LENGTH];
for(int i=0; i < LENGTH; i++){
returnArray[i] = "" + v.elementAt(i);
return returnArray;