Executing untokenized command line from Java

Question

I am currently using ProcessBuilder to run commands from a java server. This server is to replace an old Perl server, and a lot of our legacy code specifies platform specific command lines.

For instance, on windows it might do:

command -option "hello world"

and on unix it might do:

command -option 'hello world'

The problem is that ProcessBuilder and Runtime.exec both take in tokenized command lines (e.g., {"command", "-option", "hello world"} for both unix and windows).

While I prefer the platform independant way, we have somewhere in the range of 30 million lines of perl code in our codebase. Without me writing a tokenizer for the different platforms (not a big deal really, I just don't want to make a WTF), is there a way to let the shell on the operating system tokenize the command line?

`command -option "hello world"` works on unix as well, quotes are quotes... — akuhn, Dec 30 '09 at 15:21
Regardless, our code does conditionalize on windows vs. unix, usually because the commands are more complex than that and have nested quotes and command line variables and other such nonsense. — tster, Dec 30 '09 at 15:35

Kevin · Accepted Answer · 2009-12-30T15:52:30.050

7

Are you able to use the overloaded Runtime.exec(String) that takes a single String and runs that as the entire command?

The following works for me on Windows:

Process p = Runtime.getRuntime().exec("perl -e \"print 5\"");
System.out.println(IOUtils.toString(p.getInputStream()));
p.destroy();

This is more or less what Runtime.exec(String) is doing:

public static void main(String [] args) throws Exception {
    Process p = new ProcessBuilder(getCommand("perl -e \"print 5\"")).start();
    System.out.println(IOUtils.toString(p.getInputStream()));
    p.destroy();

}

private static String[] getCommand(String input) {
    StringTokenizer tokenizer = new StringTokenizer(input);
    String[] result = new String[tokenizer.countTokens()];
    for (int i = 0; tokenizer.hasMoreTokens(); i++) {
        result[i] = tokenizer.nextToken();
    }
    return result;
}

edited Dec 30 '09 at 15:52

answered Dec 30 '09 at 15:23

Kevin

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Is Perl on the path for the environment that the process is executing in? – Kevin Dec 30 '09 at 15:35
Oops, I just realized that I was using ProcessBuilder, not Runtime.exec(). – tster Dec 30 '09 at 15:37
Is there anyway to use Runtime.exec() without loosing the ability to redirect stderr to stdout? – tster Dec 30 '09 at 15:43
1

It doesn't appear so. However, if you look under the covers for Runtime.exec(String), you'll see it is simply using a StringTokenizer to parse the arguments into an array and then passing that to ProcessBuilder. Perhaps you could do something similar – Kevin Dec 30 '09 at 15:50

score 5 · Answer 2 · answered Dec 30 '09 at 16:01

I think the quotes are being interpreted by the shell. Instead, put the command in a shell script:

$ cat temp.sh 
#!/bin/sh
perl -e "print 5"

and execute it:

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

public class PBTest {

    public static void main(String[] args) {
        ProcessBuilder pb = new ProcessBuilder("./temp.sh");
        pb.redirectErrorStream(true);
        try {
            Process p = pb.start();
            String s;
            BufferedReader stdout = new BufferedReader (
                new InputStreamReader(p.getInputStream()));
            while ((s = stdout.readLine()) != null) {
                System.out.println(s);
            }
            System.out.println("Exit value: " + p.waitFor());
            p.getInputStream().close();
            p.getOutputStream().close();
            p.getErrorStream().close();
         } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
}

Console:

5
Exit value: 0

Executing untokenized command line from Java

2 Answers2

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