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Re: [Groff] [PATCH] Use bash for several contrib scripts

From: Ingo Schwarze
Subject: Re: [Groff] [PATCH] Use bash for several contrib scripts
Date: Fri, 3 Jan 2014 01:41:32 +0100
User-agent: Mutt/1.5.21 (2010-09-15)


Tethys wrote on Fri, Jan 03, 2014 at 12:06:31AM +0000:
> Colin Watson writes:

>>Perhaps just:
>>  tmp=$d/eqn2graph$${$RANDOM:+-$RANDOM}

That, or just

  tmp=$d/eqn2graph$$-`date +%Y%m%d%H%M%S`

A collision is not dangerous in terms of security,
and we are only talking about a fallback solution
for systems lacking a proper mktemp(1), so having
something that is pure POSIX and improbable to collide
is maybe better than hoping for urandom(4) and sum(1);
i admit the latter comes from V2 AT&T UNIX, but it isn't
standardized by POSIX.


> Since it's not guaranteed to be present, why not just ignore $RANDOM
> and use our own randomly generated integer instead? Something like:
>       groff_rand=$(dd if=/dev/urandom bs=8 count=1 2>/dev/null | sum | sed 
> 's/^0*//;s/ .*//')
>       tmp="$d/eqn2graph$groff_rand"
> should work and be portable. I think pretty much everywhere supports
> /dev/urandom, right? If not we could use /dev/random with the minimal
> chance of it blocking.
> Tet

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