exec does not execute a command in your shell

try

CopyProcess p = Runtime.getRuntime().exec(new String[]{"csh","-c","cat /home/narek/pk.txt"});

instead.

EDIT:: I don't have csh on my system so I used bash instead. The following worked for me

CopyProcess p = Runtime.getRuntime().exec(new String[]{"bash","-c","ls /home/XXX"});

I am not sure if you are asking about Shell command execution, or ipconfig in general.

If the first is the case here: Yep, you can use Runtime.getRuntime.exec(). Related Answers (In Stackoverflow):

1. Executing shell commands from Java
2. Want to invoke a linux shell command from Java

Moreover to the answers provided there, here is my example on how you do it with "host -t a" command for DNS lookups. I would generally recommend to read through the list you get and append them in an String for logging purposes.

p = Runtime.getRuntime().exec("host -t a " + domain);
p.waitFor();
     
BufferedReader reader = 
  new BufferedReader(new InputStreamReader(p.getInputStream()));
     
String line = "";           
while ((line = reader.readLine())!= null) {
    sb.append(line + "\n");
}

The other solution which herausuggested was to use ProcessBuilderand execute the command from there. For this you need to use Java SE 7 upwards. Here is an example that starts a process with a modified working directory and environment, and redirects standard output and error to be appended to a log file:

 ProcessBuilder pb =
   new ProcessBuilder("myCommand", "myArg1", "myArg2");
 Map<String, String> env = pb.environment();
 env.put("VAR1", "myValue");
 env.remove("OTHERVAR");
 env.put("VAR2", env.get("VAR1") + "suffix");
 pb.directory(new File("myDir"));
 File log = new File("log");
 pb.redirectErrorStream(true);
 pb.redirectOutput(Redirect.appendTo(log));
 Process p = pb.start();
 assert pb.redirectInput() == Redirect.PIPE;
 assert pb.redirectOutput().file() == log;
 assert p.getInputStream().read() == -1;

If you wanna know more about ProcessBuilder, read through the documentation: Oracle Documentation on Class ProcessBuilder

You can use java.lang.Runtime.exec to run simple code. This gives you back a Process and you can read its standard output directly without having to temporarily store the output on disk.

For example, here's a complete program that will showcase how to do it:

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class testprog {
    public static void main(String args[]) {
        String s;
        Process p;
        try {
            p = Runtime.getRuntime().exec("ls -aF");
            BufferedReader br = new BufferedReader(
                new InputStreamReader(p.getInputStream()));
            while ((s = br.readLine()) != null)
                System.out.println("line: " + s);
            p.waitFor();
            System.out.println ("exit: " + p.exitValue());
            p.destroy();
        } catch (Exception e) {}
    }
}

When compiled and run, it outputs:

line: ./
line: ../
line: .classpath*
line: .project*
line: bin/
line: src/
exit: 0

as expected.

You can also get the error stream for the process standard error, and output stream for the process standard input, confusingly enough. In this context, the input and output are reversed since it's input from the process to this one (i.e., the standard output of the process).

If you want to merge the process standard output and error from Java (as opposed to using 2>&1 in the actual command), you should look into ProcessBuilder.

create a file named "sync" in /usr/bin containing the following:

java -jar {PATH TO JARFILE} $1 $2

Replace {PATH TO JARFILE} with the path to the jarfile

Make the file executable by typing chmod +x sync while in /usr/bin

Are you processing the standard input and standard output? From the javadocs:

Because some native platforms only provide limited buffer size for standard input and output streams, failure to promptly write the input stream or read the output stream of the subprocess may cause the subprocess to block, and even deadlock.

Process cmdProc = Runtime.getRuntime().exec(command);


BufferedReader stdoutReader = new BufferedReader(
         new InputStreamReader(cmdProc.getInputStream()));
String line;
while ((line = stdoutReader.readLine()) != null) {
   // process procs standard output here
}

BufferedReader stderrReader = new BufferedReader(
         new InputStreamReader(cmdProc.getErrorStream()));
while ((line = stderrReader.readLine()) != null) {
   // process procs standard error here
}

int retValue = cmdProc.exitValue();