shell command needs whitespace characters escaped

[metaperl]

I downloaded a file which has a space in the filename. I want to run a
shell unzip on it, but it fails in my current code:

        syscmd = "cd %s ; unzip %s" % (self.storage.input,
file.basename())
        os.system(syscmd)

because no escaping was done.

Is there a more principled way to construct a shell command and execute
it so that all necessary characters are escaped?