perl -pi.bak -e 's/OLDSTRING/NEWSTRING/g' FILELIST #### for my $file (@files){ open IN,"$directory/$file" or die "Can't read $directory/$file Error: $!\n"; open OUT,">$directory/$file.out" or die "Can't write $directory/$file.out Error: $!\n"; while(){ chomp; # remove newline so new data on same (?correct?) line print OUT $_; print OUT "\t\t $file" if /