Using ruby gem/command from python

I've 开发者_如何学运维installed the Ruby gem 'haml' on my mac, which I can use to compile haml files into html files using the following command at the terminal:

haml 'path/to/haml/file.haml' 'desired/html/path/file.html'

This command simply creates an html file at the second path, and gives no output in the terminal. So for example, this command:

haml "/Volumes/Macintosh HD/Users/me/Sites/ICSP/sugar.haml" "/Volumes/Macintosh HD/Users/me/Sites/ICSP/sugar.html"

Creates a sugar.html file at the given path. Now I'm trying to use this functionality from a python script. When I type this into IDLE's interactive python shell:

>>>import subprocess
>>>subprocess.Popen('haml "/Volumes/Macintosh HD/Users/me/Sites/ICSP/sugar.haml"        "/Volumes/Macintosh HD/Users/me/Sites/ICSP/sugar.html"', shell=True, executable='/bin/bash')
<subprocess.Popen object at 0x159d6f0>

I get output suggesting that the process has been run, however, there is no file outputted. Why is this happening? I even put in the Shell argument, but no interactive shell shows up. Also, I read somewhere that the default shell used is not bash, which is what the Mac terminal uses, so I put that in too for good measure.

Following icktoofay's advice, I ran check_call. Here is the traceback I received:

Traceback (most recent call last):

File "/Users/neil/Desktop/subprocesstest.py", line 7, in p = subprocess.check_call(x, shell=True) File "/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/subprocess.py", line 504, in check_call raise CalledProcessError(retcode, cmd) CalledProcessError: Command 'haml "/Volumes/Macintosh HD/Users/neil/Sites/ICSP/sugar.haml" "/Volumes/Macintosh HD/Users/neil/Sites/ICSP/sugar.html"' returned non-zero exit status 127

According to the bash reference manual, while searching for a command to be executed,

If the name is neither a shell function nor a builtin, and contains no slashes, Bash searches each element of $PATH for a directory containing an executable file by that name. ... If that function is not defined, the shell prints an error message and returns an exit status of 127.

However, I thought it was indeed finding the haml command after adding the shell and executable arguments, because before that, it was giving a 'file or directory not found error', which indicates that the function is not executable directly but rather in a shell only.

Now how do I make python find this haml command? Or would I have to use some ugly workaround like an applescript which then invokes the haml command.

---

I see that you are using, shell=True, so I would have expected things to just work. Checked it locally here with Python 2.7.1 and haml 3.1.1 and I had no problems executing it. There are also some python implementations you might be interested in, PyHAML, HamlPy, djaml or django-haml.

import subprocess
subprocess.Popen(['haml', 'hello.haml', 'hello.html'], shell=True)

% cat hello.html
<strong class='code' id='message'>Hello, World!</strong>

---

shlex.split() is your friend, when you want to build args list suitable for Popen and its ilk.

>>> import subprocess
>>> import shlex
>>> p = subprocess.Popen(shlex.split('haml "/Volumes/Macintosh HD/Users/me/Sites/ICSP/sugar.haml" "/Volumes/Macintosh HD/Users/me/Sites/ICSP/sugar.html"'))
>>> p.wait()
0