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Date: Thu, 4 Aug 2011 01:42:34 -0700
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Subject: Re: Snippet: The leanest Popen wrapper
From: Chris Rebert <clp2@rebertia.com>
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Xref: x330-a1.tempe.blueboxinc.net comp.lang.python:10850

On Thu, Aug 4, 2011 at 1:10 AM, Thomas Rachel
<nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de>
wrote:
> Am 03.08.2011 19:27 schrieb Chris Rebert:
>
>>> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 s=
hell=3D True,
>>
>> I would strongly encourage you to avoid shell=3DTrue.
>
> ACK, but not because it is hard, but because it is unnecessary and uneleg=
ant
> at this point.
>
>> You really don't want to have to worry about doing proper shell escaping
>> yourself.
>
> That's nothing to really worry about - just doing
>
> def shellquote(*strs):
> =C2=A0 =C2=A0 =C2=A0 =C2=A0return " ".join([
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0"'"+st.replace("'"=
,"'\\''")+"'"
> =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0 =C2=A0for st in strs
> =C2=A0 =C2=A0 =C2=A0 =C2=A0])
>
> would do perfectly: shellquote('echo', "'", '"', " ", "\n")

I was considering the more general case where one of the strings may
have come from user input. You then need to also escape
$looks_like_a_var, `some_command`, and way more other such stuff that
your simple function doesn't cover. Even if the user is trusted, not
escaping such things can still lead to bizarre unintended
output/results.

If the commands are completely static, then yes, I agree that lack of
necessity then becomes the main argument against shell=3DTrue.

Cheers,
Chris
--
http://rebertia.com