Actually I've checked output for perl -V :

$ perl -V  | grep SEED
    PERL_HASH_SEED="-1"
[download]

But setting the PERL_HASH_SEED env variable has no effect at all. Using this script :

#!/usr/bin/perl
use strict;
use warnings;
use Hash::Util qw(hash_seed);

my %t=qw( a A b B c C d D e E f F );

print hash_seed() . "\n";

print join( '', %t) ."\n";
[download]

I change the PERL_HASH_SEED, the hash_seed differs from run to run, but the hash order remains the same:

$ for i in -1 0 1 42 garbage; do export PERL_HASH_SEED=$i; for j in 1 
+2 3; do perl test.pl; done; done
3657515954
eEcCaAbBdDfF
3070542819
eEcCaAbBdDfF
185686570
eEcCaAbBdDfF
0
eEcCaAbBdDfF
0
eEcCaAbBdDfF
0
eEcCaAbBdDfF
1
eEcCaAbBdDfF
1
eEcCaAbBdDfF
1
eEcCaAbBdDfF
42
eEcCaAbBdDfF
42
eEcCaAbBdDfF
42
eEcCaAbBdDfF
3381895560
eEcCaAbBdDfF
2632524130
eEcCaAbBdDfF
1729561246
eEcCaAbBdDfF
[download]

The hash seed has no effect, that sucks!

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