Write an executable .sh file with Java for OSX

Question

So I am trying to write an .sh file that will be executable, this is how I'm currently writing it:

Writer output = null;

try {
  output = new BufferedWriter(new FileWriter(file2));
  output.write(shellScriptContent);
  output.close();
} catch (IOException ex) {
  Logger.getLogger(PunchGUI.class.getName()).log(Level.SEVERE, null, ex);
}

So that writes the file just fine, but it is not executable. Is there a way to change the executable status when I write it?

Edit: To further clarify, I am trying to make it execute by default, so that for instance, if you double clicked the generated file, it would automatically execute.

score 27 · Answer 1 · answered Mar 23 '09 at 15:00

27

You can call File.setExecutable() to set the owner's executable bit for the file, which might be sufficient for your case. Or you can just chmod it yourself with a system call with Process.

Alas, full-powered programmatic alteration of file permissions isn't available until Java 7. It'll be part of the New IO feature set, which you can read more about here.

answered Mar 23 '09 at 15:00

John Feminella

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Thanks, but unfortunately, I'm working with 1.5. It has to have pretty broad compatibility for OSX, and most people don't have 1.6. – Glenn Mar 24 '09 at 02:24
In that case, you're stuck with my alternate solution of using chmod with a system call. Sorry! – John Feminella Mar 24 '09 at 02:28

user49913 · Accepted Answer · 2009-03-23T15:49:59.763

You'd need to chmod it, and you can probably do it by exec'ing a system command like such:

Really all you'd need is to fire off something like this:

Runtime.getRuntime().exec("chmod u+x "+FILENAME);

But if you want to keep track of it more explicitly can capture stdin / stderr then something more like:

Process p = Runtime.getRuntime().exec("chmod u+x "+FILENAME);
BufferedReader stdInput = new BufferedReader(new InputStreamReader(p.getInputStream()));    
BufferedReader stdError = new BufferedReader(new InputStreamReader(p.getErrorStream()));

Which I got from here: http://www.devdaily.com/java/edu/pj/pj010016/pj010016.shtml

Update:

Test program:

package junk;
import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.io.Writer;

public class Main{
  private String scriptContent = '#!/bin/bash \n echo "yeah toast!" > /tmp/toast.txt';
  public void doIt(){
    try{
      Writer output = new BufferedWriter(new FileWriter("/tmp/toast.sh"));
      output.write(scriptContent);
      output.close();
      Runtime.getRuntime().exec("chmod u+x /tmp/toast.sh");
    }catch (IOException ex){}
  }

  public static void main(String[] args){
    Main m = new Main();
    m.doIt();
  }

}

On linux if you open up a file browser and double click on /tmp/toast.sh and choose to run it, it should generate a text file /tmp/toast.txt with the words 'yeah toast'. I assume Mac would do the same since it's BSD under the hood.

Thanks for the suggestion! Will this also make it automatically execute when double clicked? — Glenn, Mar 23 '09 at 15:01
It should, assuming the user running the java program is the same who will run the shell script. Otherwise you could adjust the chmod to a+x which means all users have execute permission. I did a small test program on linux and it worked for me. — user49913, Mar 23 '09 at 15:44
You saved the day dude, i was getting around how to execute a script from within java and turns out all i needed to do was make it executable via the `chmod` command ! Thanks — redDragonzz, Jan 17 '13 at 02:11

mkobit · Answer 3 · 2018-08-27T15:35:22.443

In Java 7 you can call Files.setPosixFilePermissions. Here is an example:

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.nio.file.attribute.PosixFilePermission;
import java.util.Set;

class FilePermissionExample {
  public static void main(String[] args) throws IOException {
    final Path filepath = Paths.get("path", "to", "file.txt");
    final Set<PosixFilePermission> permissions = Files.getPosixFilePermissions(filepath);
    permissions.add(PosixFilePermission.OWNER_EXECUTE);
    Files.setPosixFilePermissions(filepath, permissions);
  }
}

score 2 · Answer 4 · answered Mar 23 '09 at 15:55

2

On Mac OS X, besides chmod +x, you have to give a .command extension to your shell script if you want to launch it with a double-click.

answered Mar 23 '09 at 15:55

mouviciel

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score 1 · Answer 5 · edited May 23 '17 at 11:47

1

This answer I wrote for the question how do I programmatically change file permissions shows a chmod example via a native call using jna, which should work on Mac OS X.

edited May 23 '17 at 11:47

Community

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1

answered Mar 23 '09 at 19:32

Marty Lamb

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1
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Write an executable .sh file with Java for OSX

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