What do you mean by "xx"? A "constant" string? For example, if $foo = 'GOAT', you mean to match strings like: 
G..O..A..T
GaaOaaAaaT
GabcOabcAabcT
G<<<<<O<<<<<A<<<<<T
If this assumption is correct, this is a possible way (yet quite inefficient) to handle it: 
my @foo = split //, $foo;
$foo = shift(@foo) . q{(.*?)} . join q{\2}, @foo;

while ( my $line = <FH> ) {
    s/($foo)/$stuff1$1$stuff2/g;
}

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--
AltBlue.

In reply to Re: More Regexp Confusion by AltBlue
in thread More Regexp Confusion by mdunnbass

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