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author | Jarkko Hietaniemi <jhi@iki.fi> | 2003-07-11 00:21:43 +0000 |
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committer | Jarkko Hietaniemi <jhi@iki.fi> | 2003-07-11 00:21:43 +0000 |
commit | 99c877a1ede996bce9129fe302f92f7e1ed9b77d (patch) | |
tree | 845807d99817ec0a5575772d5736a988a986206d /pod/perlrun.pod | |
parent | b90ada5a1675d8de9e79ad2a4437d0678a700f67 (diff) | |
download | perl-99c877a1ede996bce9129fe302f92f7e1ed9b77d.tar.gz |
New order of seed.
p4raw-id: //depot/perl@20139
Diffstat (limited to 'pod/perlrun.pod')
-rw-r--r-- | pod/perlrun.pod | 19 |
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. |