On Thu, May 27, 2010 at 05:54:21PM +0200, Carsten Aulbert wrote:
> On Thursday 27 May 2010 17:43:37 Alexander Wirt wrote:
>
> > Ok, let me see:
> > libc6-dev-i386: libc6-dev-i386 | 2.7-18lenny1 | stable | amd64
> > 2.7 is smaller than 2.3.0 so this won't work with lenny.
>
> I am confused...
>
> $ dpkg --compare-versions "2.7" ">>" "2.3.0"; echo $?
> 0
>
> Why is 2.7 smaller than 2.3.0?
Erm, it's not smaller - it's just as it should be :) From
dpkg's manual page:
dpkg returns success (zero result) if the specified condition is
satisfied, and failure (nonzero result) otherwise.
In this case, the condition *is* satisfied, so dpkg returns zero.
The idea here is that in Unix programs, a zero exit code signifies
success, not error, and thus, in Bourne shell scripting, the "if"
and "while" conditionals are satisfied by a zero exit code and
fail on anything else. So:
if dpkg --compare-versions 2.7 '>>' 2.3.0; then
echo 'Everything is just fine!'
fi
...would succeed precisely because dpkg returns zero :)
HTH, HAND.
G'luck,
Peter
--
Peter Pentchev roam@ringlet.net roam@space.bg roam@FreeBSD.org
PGP key: http://people.FreeBSD.org/~roam/roam.key.asc
Key fingerprint FDBA FD79 C26F 3C51 C95E DF9E ED18 B68D 1619 4553
Attachment:
signature.asc
Description: Digital signature