srand
Seeds the pseudo-random number generator used by rand.
Sets the seed for the random number generator used by rand. If EXPR
is provided and defined, its integer value is used. Otherwise, a
system-derived seed (nanosecond timestamp XOR PID) is used. Creates a
new StdRng instance via seed_from_u64. Returns the seed that was
actually used as an integer.
Synopsis
srand(42); # deterministic sequence
srand; # seed from system entropy
my $seed = srand; # returns the seed used