use File::Find;
use strict;
use warnings;

my $dir = "path";

find(\&process, $dir);

sub process {
        my $file = $_;
        my @newFile;

        open (FILE, "<$file");
        while (my $line = <FILE>){
                if ( $line =~ s/(print)\s*("\w+")/\$lang->$1($2, \$actUser->{'lang'})/g ){
                        print "\nFound: $1, $2\n";
                }
                push @newFile, $line;
        }
        close FILE;
        open (FILE, ">$file");
        foreach my $line (@newFile){
                #print FILE $line;
                print $line;
        }
        close FILE;
}

readline() on closed filehandle FILE at  line 25.

sub process {
        opendir(DIR, $dir) or die $!;
        (my $file) = grep { $_ !~ m/^\.{1,2}$/ } readdir(DIR);
        closedir(DIR) or die $!;

        my @newFile;

        open (FILE, "<$file") or die $!;
        while (my $line = <FILE>){
                if ( $line =~ s/(print)\s*("\w+")/\$lang->$1($2, \$actUser->{'lang'})/g ){
                        print "\nFound: $1, $2\n";
                }
                push @newFile, $line;
        }
        close FILE;
        open (FILE, ">$file");
        foreach my $line (@newFile){
                print FILE $line;
                #print $line;
        }
        close FILE;
}

sub process {
   opendir(DIR, $dir) or die $!;
   my @file = grep { $_ !~ m/^\.{1,2}$/ } readdir(DIR);
   closedir(DIR);

   my @newFile;

   for (my $i = 0; $i <= $#file; $i++) {
      open (FILE, "<$file[$i]") or die $!;
      while (my $line = <FILE>){
         if ( $line =~ s/(print)\s*("\w+")/\$lang->$1($2, \$actUser->{'lang'})/g ){
            print "\nFound: $1, $2\n";
         }
         push @newFile, $line;
      }
      close FILE;
      open (FILE, ">$file[$i]");
      foreach my $line (@newFile){
         print FILE $line;
         #print $line;
      }
      close FILE;
   }
}