Bug or unwanted behaviour in echo ?

[David Wolfskill]

On Thu, Jan 08, 2009 at 01:37:06PM +0100, Damien Fleuriot wrote:
> ...
> I was toying around with a site that proposed to hash passwords to
> MD5, and comparing results with my host running FreeBSD 7.0-STABLE
> 
> At some point I didn't get the same hash from the website and from BSD.
> 
> On BSD:
> echo -n "test'$@" | md5
> 5c28a8c6d799d302f3ef53afefdfc81b
> 
> On website:
> f883cdacbb478c241c51da1f67fbe9bf
> 
> After swapping characters around I realized that echo just interprets
> $@ (which in our case is null).

Errr... no, I think you will find that what echo saw was actually
a string whose md5 hash was "5c28a8c6d799d302f3ef53afefdfc81b".
The "$@" was seen as a token by the shell, its value interpolated,
and passed along to echo (which may well have been a shell builtin
in any case, depending on what shell you were using).

That's what escaping the "$" worked.

> ... 

Peace,
david
-- 
David H. Wolfskill				david at catwhisker.org
Depriving a girl or boy of an opportunity for education is evil.

See http://www.catwhisker.org/~david/publickey.gpg for my public key.
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