shell command needs whitespace characters escaped

[Nick Craig-Wood]

Fredrik Lundh <fredrik at pythonware.com> wrote:
>  metaperl wrote:
> 
> > 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?
> 
>  use subprocess.list2cmdline to create the command string

That is windows only isn't it?

  >>> subprocess.list2cmdline(['a', "'b", 'c'])
  "a 'b c"

Doesn't make a unix shell friendly command line.

For unix you can use this

def quotemeta(args):
    """Quote all the metacharacters in the args for the unix shell"""
    return " ".join([re.sub(r"([^A-Za-z0-9_])", r"\\\1", string) for string in args])

>>> print quotemeta(['a', "'b", 'c'])
a \'b c

> (or better, subprocess.call).

A good idea!

-- 
Nick Craig-Wood <nick at craig-wood.com> -- http://www.craig-wood.com/nick