#!/usr/bin/perl -l

my $s = "Aggregate:    f3050-184-160:EmptyAggr";

my ($first, $rest) = split /:/, $s, 2;
#                                   ^

print "\$first: '$first'";
print "\$rest:  '$rest'";

__END__
$first: 'Aggregate'
$rest:  '    f3050-184-160:EmptyAggr'