Please use code tags!

Your problem lies in the line

my $content =~ m/(\/$string\/a-z*)/g;
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This tries to match your pattern against the string in $content which is not defined at this point in time. You could try something like:

my @content = $_ =~ m/(\/$string\/a-z*)/g;
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which captures all matches into the array @content.

What is also funny about your code is the loop foreach(@daten){. You do not seem to be using the elements of @daten anywhere. Should this not be something like foreach my $daten (@daten){?