Question

By default, perl prints \r\n in a win32 environment. How can I override this? I’m using perl to make some changes to some source code in a repository, and I don’t want to change all the newline characters.

I tried changing the output record separator but with no luck.

Thanks!

Edit: Wanted to include a code sample – I’m doing a search and replace over some files that follow a relatively straightforward pattern like this:

#!/usr/bin/perl
# test.pl

use strict;
use warnings;

$/ = undef;
$\ = "\n"; 
$^I=".old~";

while (<>) {
  while (s/hello/world/) {

  }
  print;
}

This should replace any instances of “hello” with “world” for any files passed on the cmd line.

Edit 2: I tried the binmode as suggested without any luck initially. I delved a bit more and found that $^I (the inplace edit special variable) was overriding binmode. Any work around to still be able to use the inplace edit?

Edit 3: As Sinan points out below, I needed to use binmode ARGVOUT with $^I instead of binmode STDOUT in my example. Thanks.

Answer 1

Printing "\n" to a filehandle on Windows emits, by default, a CARRIAGE RETURN ("\015") followed by a LINE FEED ("\012") character because that the standard newline sequence on Windows.

This happens transparently, so you need to override it for the special filehandle ARGVOUT (see perldoc perlvar):

#!/usr/bin/perl -i.bak

use strict; use warnings;

local ($\, $/);

while (<>) {
    binmode ARGVOUT;
    print;
}

Output:

C:\Temp> xxd test.txt
0000000: 7465 7374 0d0a 0d0a                      test....

C:\Temp> h test.txt

C:\Temp> xxd test.txt
0000000: 7465 7374 0a0a                           test..

See also perldoc open, perldoc binmode and perldoc perliol (thanks daotoad).