1: $filename is presumably a string, not a pattern, which you want to match; so you have to escape metacharacters first if you're going to use it in a regular expression: /\Q$filename\E/, for example, if you don't want to modify that variable with the quotemeta function or don't need the quoted version for anything else ($foo = quotemeta $foo; or my $foo_quoted = quotemeta $foo;</code>).

2:

In reply to Re: How to grep for a filename for each of the keys of a hash by Anonymous Monk
in thread How to grep for a filename for each of the keys of a hash by perl_mystery

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