If I understand you correctly, you'd like to have a regex that extracts digits out of a filename pattern. This pattern contains normal characters matching \w as well as one occurrence of '@' - separated from the rest by '.'

Then the following should do what you want:

my $pattern = shift @ARGV;
my $name = shift @ARGV;

# quotemeta is important to quote all the special
# regex chars in the filename pattern
$pattern = quotemeta $pattern;

# the @ got escaped to '\@' so we have to look for
# this sequence instead
$pattern =~ s/\\@/(\\d+)/;

die 'more than one "@" in pattern' if $pattern =~ tr/@//;

my ($number) = $name =~ /^$pattern$/;

print $number, $/;
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This just replaces the '@' in the string with the capturing '(\d+)' and then does the match. You don't even need the '.' as delimiters - as long as you can ensure that there are only non-digits left and right of the '@'.

-- Hofmator