I can not reproduce your results, in part because your results are strange.
It would help if you posted a complete example that demonstrates your problem, and enclose that in <code> tags. Here's what I used to test:
use 5.010; use strict; use warnings; use Carp; my $var = 'QeTEv2804'; printf "%s.\n", $var; open my $debug, '>>', 'debug.txt' or confess "Couldn't open file: $!"; printf $debug "%s.\n", $var; close $debug;
$> hexdump -C debug.txt 00000000 51 65 54 45 76 32 38 30 34 2e 0a |QeTEv2804 +..| 0000000b
In your output, those control characters are NULs, not line endings, and they somehow come before the `.' in your output, suggesting they are part of $var itself. If I append NULs: $var = "QeTEv2804\0\0\0"; and re-run the above script, the output still looks like this, because those \0s are unprintable:QeTEv2804.
Are you sure this is your actual code? Something seems fishy.
Edit: Took out irrelevant info from above paragraph and added example that reproduces the OP's result.
Another thing I'd suggest is to always use the 3-argument open with lexical file handle, as I did in my example. It won't affect your results in this case, but it's a best practice.