Question

I am attempting to create a Python script that in turn runs the shell script “js2coffee” to convert some javascript into coffeescript.

From the command line I can run this, and get coffeescript back again…

echo "var myNumber = 100;" | js2coffee

What I need to do is use this same pattern from Python.

In Python, I’ve come to something like this:

command = "echo '" + myJavscript + "' | js2coffee"
result = os.popen(command).read()

This works sometimes, but there are issues related to special characters (mostly quotes, I think) not being properly escaped in the myJavascript. There has got to be a standard way of doing this. Any ideas? Thanks!

Answer 1

Use the input stream of a process to feed it the data, that way you can avoid the shell and you don’t need to escape your javascript. Additionally, you’re not vulnerable to shell injection attacks;

pr = subprocess.Popen(['js2coffee'], 
                      stdin=subprocess.PIPE,  
                      stdout=subprocess.PIPE)
result, stderrdata = pr.communicate('var myNumber = 100;')