Compiling on a 64 bit Linux

I’m currently in the process of upgrading my old server to a nice new 64 bit CentOS 5 install and came across a few issues rebuilding some of the packages.
In general I try not to use customised versions of packages since it makes updating the machine so much easier when there’s nothing to rebuild, however some things I do customise slightly such as Apache and Exim.
Whilst rebuilding the Exim RPM I came across some strange errors which I assumed (correctly) were to do with the fact that it was a 64 bit OS not 32 bit.

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Merging two hashrefs in Perl

I came across an interesting and very simple way to merge the contents of two hashrefs today. A hash is made up of pairs – a key and a corresponding value. As an example, the following can be pasted into a shell session on most machines that have perl installed.
perl -MData::Dumper -le ‘
$x = { a => 1, b => 2 };
$y = { c => 3, d => 4 };
$x = { %$x, %$y };
print Dumper($x);

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