Don't declare all your variables in a single statement ($re, $lin, ...). That almost completely negates scope checking provided by strict and tell readers of the code nothing about the correct scope of variables. Instead declare each variable where it is first used:

my (@inarr) = (
    'stuff{tag}<igo;123>stuff<ig;abc>',
    '<igt;ddd>stuff blah {foo}',
    'stuff blah foo <igxo;dsldkd.eps>',
    '<igt;aaa>stuff blah <igx;hhh>'
    );
my $re = '<(ig|igt|igo|igxo);.+?>';

for my $lin (@inarr) {
    my @g = ($lin =~ m/$re/g);
}
[download]

Also note use of indentation (Perl Tidy is your friend) so it's easy to see how blocks are nested (and avoid the need to correctly comment } as an aid to matching braces).

In particular note that @g is local to the for loop block. No simple way to tell that if you declare it globally to the loop.

Even worse, $lin looks like a normal variable declared globally, but isn't. Loop variables are magical (they are aliased to each loop value in turn) and are not the same as a lexical variable global to the for loop that may share the same name.