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authorJarkko Hietaniemi <jhi@iki.fi>2003-07-11 00:21:43 +0000
committerJarkko Hietaniemi <jhi@iki.fi>2003-07-11 00:21:43 +0000
commit99c877a1ede996bce9129fe302f92f7e1ed9b77d (patch)
tree845807d99817ec0a5575772d5736a988a986206d /pod/perlrun.pod
parentb90ada5a1675d8de9e79ad2a4437d0678a700f67 (diff)
downloadperl-99c877a1ede996bce9129fe302f92f7e1ed9b77d.tar.gz
New order of seed.
p4raw-id: //depot/perl@20139
Diffstat (limited to 'pod/perlrun.pod')
-rw-r--r--pod/perlrun.pod19
1 files changed, 10 insertions, 9 deletions
diff --git a/pod/perlrun.pod b/pod/perlrun.pod
index 730c75da1e..2a57b6c4a9 100644
--- a/pod/perlrun.pod
+++ b/pod/perlrun.pod
@@ -1109,19 +1109,20 @@ PERL_ENCODING environment variable is consulted for an encoding name.
=item PERL_HASH_SEED
(Since Perl 5.8.1.) Used to randomise Perl's internal hash function.
-To emulate the pre-5.8.1 behaviour, set to an integer (zero means
-exactly the same order as 5.8.0). "Pre-5.8.1" means, among other
-things, that hash keys will be ordered the same between different runs
-of Perl.
-The default behaviour is to randomise unless the PERL_HASH_SEED is set.
-If Perl has been compiled with C<-DUSE_HASH_SEED_EXPLICIT>, the default
-behaviour is B<not> to randomise unless the PERL_HASH_SEED is set.
+The default behaviour is B<not> to randomise if the PERL_HASH_SEED is
+unset. If Perl has been compiled with C<-DUSE_HASH_SEED>, the default
+behaviour B<is> to randomise. If Perl hash been compiled with
+C<-DNO_HASH_SEED>, the hash randomisation is completely disabled.
+
+If PERL_HASH_SEED is set to a numeric (positive integer) string,
+that is used as the seed.
If PERL_HASH_SEED is unset or set to a non-numeric string, Perl uses
the pseudorandom seed supplied by the operating system and libraries.
-This means that each different run of Perl will have a different
-ordering of the results of keys(), values(), and each().
+
+The seed being set means that each different run of Perl will have
+a different ordering of the results of keys(), values(), and each().
See L<perlsec/"Algorithmic Complexity Attacks"> for more information.