print "-"x80,"\n";
$a = 1;
@a = (1..10);
%a = (10..20);
open(a,"/etc/passwd") or die "can't open /etc/passwd : $!";
sub a { "TEST" };
format a =
@>>>>>>>>
.
&DumpGlob(*a);
print "-"x80,"\n";
sub DumpGlob
{
    my $symbol = shift;
    if(defined *{$symbol}{SCALAR}) {
        print "SCALAR defined >",${*{$symbol}{SCALAR}},"<\n";
    }
    if(defined *{$symbol}{ARRAY}) {
        print "ARRAY defined >",@{*{$symbol}{ARRAY}},"<\n";
    }
    if(defined *{$symbol}{HASH}) {
        print "HASH defined >",%{*{$symbol}{HASH}},"<\n";
    }
    if(defined *{$symbol}{IO}) {
        print "IO defined >",*{$symbol}{IO},"<\n";
    }
    if(defined *{$symbol}{CODE}) {
        print "CODE defined >",*{$symbol}{CODE},"<\n";
    }
    if(defined *{$symbol}{FORMAT}) {
        print "FORMAT defined >",*{$symbol}{FORMAT},"<\n";
    }
    if(defined *{$symbol}{GLOB}){
        print "GLOB defined >",${*{$symbol}{GLOB}},"<\n";
    }
}
the output is like this

SCALAR defined >1<
ARRAY defined >12345678910<
HASH defined >1819161710111213201415<
IO defined >IO::Handle=IO(0x8154a2c)<
CODE defined >CODE(0x81735b0)<
FORMAT defined >FORMAT(0x81735f8)<
GLOB defined >*main::a<