my $extlist = join('|', @extensions);

##</code><code>##

my $extlist = join('|', map {quotemeta} @extensions);

##</code><code>##

my $re = qr/some_text=".*\.(?:$extlist)"/;

##</code><code>##

my $re = qr/some_text=".*\.(?:$extlist)"$/;