Question

I am trying to do a replace of a specific set of characters in a file in Perl but it does not seem to work, here is my code.

my $file = shift;
open(FILE, "$file") or die "File not found";
while (<FILE>){
   $data .=$_
}
$data =~ s/[^A-CEGHJ-PR-TW-Z]{1}[A-CEGHJ-NPR-TW-Z]{1}\s?[0-9]{2}\s?[0-9]{2}\s[0-9]{2}\s?[A-DEM]{0,1}$/XX012345X/g;

I know that my pattern matching works for finding the set of characters, I am not entirely sure the replace works. However, my main concern is the Perl code. The file remains untouched after I run it.

Sample File.

AB123456C Ab12345678 DG657465 GH123456FG

Answer 1

The code does not alter the file because you don’t tell it to. You open the file for reading, not writing, plus you do not print anything.

If you want a quick way to handle this, just put your regex substitution in a file and use it as a source file. Like this:

Content of regex.pl:

s/[^A-CEGHJ-PR-TW-Z]{1}[A-CEGHJ-NPR-TW-Z]{1}\s?[0-9]{2}\s?[0-9]{2}\s[0-9]{2}\s?[A-DEM]{0,1}$/XX012345X/g;

One-liner:

perl -p regex.pl inputfile.txt > output.txt

This way you can quickly check the output. You can also pipe to a pager command or not at all.