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

[Ingo Schwarze]

Hi,

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

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

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.

Yours,
  Ingo

> 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