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.i nput,
file.basename() )
os.system(syscm d)

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?

[Klaus Alexander Seistrup]

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.i nput, file.basename() )
os.system(syscm d)

because no escaping was done.

Using "cd '%s' ; unzip '%s'" as your formatting string should work.

Cheers,

--
Klaus Alexander Seistrup
http://klaus.seistrup.dk/

[Fredrik Lundh]

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.i nput,
file.basename() )
os.system(syscm d)

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.list 2cmdline to create the command string (or better,
subprocess.call ). see this FAQ entry for sample code:

http://effbot.org/pyfaq/why-can-t-ra...-backslash.htm

</F>

[Nick Craig-Wood]

Fredrik Lundh <fr*****@python ware.comwrote:

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.i nput, file.basename() )
os.system(syscm d)

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.list 2cmdline to create the command string

That is windows only isn't it?

>>subprocess.li st2cmdline(['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 <ni**@craig-wood.com-- http://www.craig-wood.com/nick