Instead of capturing and replacing all with the captured string, I'd just remove whitespace at the beginning and end of the string:

s/^\s+|\s+$//g;
[download]

one way to trim keys and values of a hash:

%hash = map { $v = $hash{$_}; s/^\s+|\s+$//g for $v,$_; $_,$v } keys %
+hash;

# another way which doesn't copy the entire has, just the keys

for my $key (keys %hash) {
    my $value = delete $hash{$key};
    for ($key, $value) {
        s/^\s+|\s+$//g;
    }
    $hash{$key} = $value;
}
[download]

_($_=" "x(1<<5)."?\n".q·/)Oo.  G°\        /
                              /\_¯/(q    /
----------------------------  \__(m.====·.(_("always off the crowd"))."·
");sub _{s./.($e="'Itrs `mnsgdq Gdbj O`qkdq")=~y/"-y/#-z/;$e.e && print}