On Sep 05 2015, Nick Coghlan <ncogh...@gmail.com> wrote:
> On 5 September 2015 at 12:36, Nikolaus Rath <nikol...@rath.org> wrote:
>> Hi Nick,
>>
>> You are giving
>>
>> runcommand(sh(i"cat {filename}"))
>>
>> as an example that avoids injection attacks. While this is true, I think
>> this is still a terrible anti-pattern[1] that should not be entombed in
>> a PEP as a positive example.
>>
>> Could you consider removing it?
>>
>> (It doubly wastes resources by pointlessly calling a shell, and then by
>> parsing & quoting the argument only for the shell to do the same in
>> reverse).
>
> Any reasonable implementation of that pattern wouldn't actually call a
> system shell, it would invoke something like Julia's command system.
That's obvious to someone like you who thinks about this in terms of the
best implementation.
To someone less experienced, or just coming at from a different angle,
this example just says "writing a shell command is a good way to start
an external program, as long as I take care of quoting".
Best,
-Nikolaus
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