What is a convenient way to execute a shell command in Python and retrieve its output?

Be very careful using the commands module, or anything that takes a string and not a list of arguments. Functions that take a string generally end up running that string through your shell. If the command you're running involves any user input, all you need is a quote, a dollar sign, a semicolon, or any of the other standard forms of injection. Even with no user input, code gets copied around and reused and evolves over time, so a variable that didn't contain spaces before might start to. I recommend always using the subprocess module, because you know that with a list of arguments, they don't get processed at all before going to the actual command you're trying to run. If you're using Python 2.7 or newer, somebody finally added a subprocess.check_output function, which does exactly what you're looking for.

I think you've already figured it out: the commands module is probably the way to go. >>> commands.getoutput('hostname') 'kashi.local' I don't believe subprocess is entirely unintuitive though. The module just allows for more fine-grained control of the process than a simple getoutput(). For example, separating out STDIN from STDERR: >>> subprocess.Popen('hostname', stdin=PIPE, stdout=PIPE).communicate() ('kashi.local\n', None)

The easiest way I'm aware of is to use commands.getoutput. >>> commands.getoutput('ls /bin/ls') '/bin/ls' http://docs.python.org/library/commands.html#commands.getoutput

The more general utility is subprocess.Popen.  Use stdout=subprocess.PIPE, stderr=subprocess.PIPE as kwargs, and then you can read from .stdout/.stderr.  (Or use communicate().)

One of the ways is to use os.popen(). The code below executes "ls" command on the terminal and prints the results: import os f = os.popen(“ls -l”) for line in f.readlines(): print line

Subprocess is definitely the way to go for flexibility and control, but here's quick and dirty: >>> print os.popen('pwd').readlines() ['/root\n']

When I'm using Python 2, I make a little function like this: def run(command): """Run command and return (output, exitCode). output is stdout/stderr combined via os.popen3 """ fin, fout = os.popen3(command) fin.close() output = fout.read() exitCode = fout.close() return output, exitCode For Python 3, clearly, subprocess is the way to go.  Forget about whether it's intuitive.  Use it a while.  The beauty of the design is only now dawning on me.

subprocess is far worse than the simple commands that it replaced. However: http://pypi.python.org/pypi/iterpipes/ is a wrapper around that raw wound that is subprocess.  Try it.

https://github.com/kennethreitz/envoy is a wrapper library around the subprocess module.