Re^2: searching string from one file in another

[Eily]

++ on the bad variable names. The fact that the variables have numbers is a first sign that the names are probably not well chosen, but having two variables with the same names (a hash and a scalar named file2) should absolutely be avoided.

Your proposition works fine if the lines in $data are unique, (the fact that they are counted using $file2{$line}++ makes me think they may not be) but will print duplicates otherwise.