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copied!<p>If you really need the controls, you can't just use <code>Popen</code>.</p> <p><code>mpg123</code> only enables terminal control if its stdin is a tty, not if it's a file or pipe. That's why you get this line in the banner:</p> <pre><code>Terminal control enabled, press 'h' for listing of keys and functions. </code></pre> <p>And the whole point of <code>Popen</code> (and <code>subprocess</code>, and the POSIX APIs it's built on) is pipes.</p> <p>So, what can you do about it?</p> <hr> <p>On linux, you can use the <a href="http://docs.python.org/3/library/pty.html" rel="nofollow"><code>pty</code></a> module. It may also work on other *nix platforms, but it may not—even if it gets built and included in your stdlib. As the docs say:</p> <blockquote> <p>Because pseudo-terminal handling is highly platform dependent, there is code to do it only for Linux. (The Linux code is supposed to work on other platforms, but hasn’t been tested yet.)</p> </blockquote> <p>It definitely runs on *BSD platforms on 2.7 and 3.3, and the example in the docs seem to work on both Mac OS X and FreeBSD… but that's as far as I've checked.</p> <hr> <p>Meanwhile, most POSIX platforms will at least have <a href="http://docs.python.org/3.3/library/os.html#os.forkpty" rel="nofollow"><code>os.forkpty</code></a>, and that's not much harder, so here's a trivial program that plays the first 5 seconds of a song passed as its first arg:</p> <pre><code>import os import pty import sys import time pid, fd = os.forkpty() if pid: time.sleep(5) os.write(fd, 'q') else: os.spawnl(os.P_WAIT, # mode '/usr/local/bin/mpg123', # path '/usr/local/bin/mpg123', '-C', sys.argv[1]) # args </code></pre> <hr> <p>Note that I used <code>os.spawnl</code> above. This is probably <em>not</em> what you want in a real program; it's for pedagogic purposes, to encourage you to read the docs (and the corresponding manpages) and understand this family of functions.</p> <p>As <a href="http://docs.python.org/3/library/os.html#os.spawnl" rel="nofollow">the docs</a> explain, this does not use the <code>PATH</code> environment variable, so you need to specify the full path to the program. You can just use <code>spawnlp</code> instead of <code>spawnl</code> to fix this.</p> <p>Also, <code>spawn</code> may (in fact, always does, although the docs aren't entirely clear) do another fork to execute the child. This really isn't necessary, but <code>spawn</code> does things that you would need to do manually if you just called <code>exec</code>. If you know what you're doing, you may well want to use <code>execl</code> (or <code>execlp</code>) instead of <code>spawnl</code>.</p> <p>You can even use most of the functionality in <code>subprocess</code> as long as you're careful (do not create any pipes, and remember that you'll end up doing <em>two</em> <code>fork</code>s, so make sure to set up the parent/child relationship properly).</p> <p>Also notice that you need to pass the path to <code>mpg123</code> <em>twice</em>—once as the path, and then once as the child program's <code>argv[0]</code>. You could also just pass <code>mpg123</code> the second time. Or, ideally, look at what <code>ps</code> says when you run it from the shell, and pass that. At any rate, you have to pass <em>something</em> as the <code>argv[0]</code>; otherwise, <code>-C</code> ends up being the <code>argv[0]</code>, which means mpg123 won't think you gave it a <code>-C</code> flag to enable control keys, but rather than you renamed it to <code>-C</code> and ran it with no flags…</p> <p>Anyway, you really do need to read the docs to understand what each of these functions does, instead of just treating it like magic code that you don't understand. So, I intentionally used the simplest possible solution to encourage that.</p> <hr> <p>On Windows, there is no such thing as a <code>pty</code>, and no way to do this at all with the facilities built in to Python. You will need to use one of the various third-party libraries for controlling a cmd.exe console (aka DOS prompt) instead.</p>

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