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POImplementing the "system" command in Java
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copied!<p>I have need for a "system" function call, the same as those in Python, Perl, PHP, Ruby, &c. It will be a component of a JavaScript standard library called Narwhal, when it's run on the Rhino JavaScript engine, which is in turn run on Java.</p> <p>The trouble is that Java's standard library appears to have abstracted away the ability to spawn a subprocess that shares the parent process's stdio. This means that you can't defer interactivity to the subprocess.</p> <p>My first crack at this was to implement Python's subprocess.popen. This uses three "pumper" threads to actively copy the parent process's stdio independently (to prevent deadlock). Unfortunately this is giving us two problems. First, the input does not close automatically when the sub-process voluntarily exits. Second, the streams to the child process do not buffer and flush properly.</p> <p>I'm looking for solutions that would make our require("os").system() command work as one would expect.</p> <p>The project is at <a href="http://narwhaljs.org" rel="nofollow noreferrer">http://narwhaljs.org</a></p> <p>Relevant code:</p> <ul> <li><a href="http://github.com/tlrobinson/narwhal/blob/d147c160f11fdfb7f3c0763acf352b2b0e2713f7/lib/os.js#L10" rel="nofollow noreferrer">http://github.com/tlrobinson/narwhal/blob/d147c160f11fdfb7f3c0763acf352b2b0e2713f7/lib/os.js#L10</a></li> <li><a href="http://github.com/tlrobinson/narwhal/blob/d147c160f11fdfb7f3c0763acf352b2b0e2713f7/engines/rhino/lib/os-engine.js#L37" rel="nofollow noreferrer">http://github.com/tlrobinson/narwhal/blob/d147c160f11fdfb7f3c0763acf352b2b0e2713f7/engines/rhino/lib/os-engine.js#L37</a></li> </ul>

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