Select Code to Download

use File::Slurp:
# get one file here, as $file
...
 $text =~ s/this/that/smg;
 rename($file, $bakfile);
 write_file($file, $text);

use Perl6::Slurp;        #<= only handles input at present
use File::Slurp;         # permits writing.
...
... with renaming here ? (see above).
 write_file($file, $text);