/gオプション

1.すべてのマッチ抜き出し
my $text = '123.456.789.101';
my @nums = $text =~ m/\d+/g;
print $_, "\n" for @nums;

----
123
456
789
101

2.反復的なマッチ
my $text = '123.456.789.101';
$text =~ m/(\d+)/g;
print "1 -> $1\n";
$text =~ m/(\d+)/g;
print "2 -> $1\n";
$text =~ m/(\d+)/g;
print "3 -> $1\n";
$text =~ m/(\d+)/g;
print "4 -> $1\n";

----
1 -> 123
2 -> 456
3 -> 789
4 -> 101

while でも同じ
my $text = '123.456.789.101';
while ($text =~ m/(\d+)/g) {
print "found : $1\n";
}
----
found : 123
found : 456
found : 789
found : 101