ipconfig output encoding ( 0D 0D 0A )

Anonymous Monk has asked for the wisdom of the Perl Monks concerning the following question:

ipconfig /?|hexdump

00000000: 0D 0D 0A 55 53 41 47 45 - 3A 0D 0D 0A 20 20 20 20 |   USAGE:
+       |
00000010: 69 70 63 6F 6E 66 69 67 - 20 5B 2F 3F 20 7C 20 2F |ipconfig 
+[/? | /|
00000020: 61 6C 6C 20 7C 20 2F 72 - 65 6E 65 77 20 5B 61 64 |all | /re
+new [ad|
00000030: 61 70 74 65 72 5D 20 7C - 20 2F 72 65 6C 65 61 73 |apter] | 
+/releas|
00000040: 65 20 5B 61 64 61 70 74 - 65 72 5D 20 7C 0D 0D 0A |e [adapte
+r] |   |
00000050: 20 20 20 20 20 20 20 20 - 20 20 20 20 20 20 2F 66 |         
+     /f|
00000060: 6C 75 73 68 64 6E 73 20 - 7C 20 2F 64 69 73 70 6C |lushdns |
+ /displ|
00000070: 61 79 64 6E 73 20 7C 20 - 2F 72 65 67 69 73 74 65 |aydns | /
+registe|
00000080: 72 64 6E 73 20 7C 0D 0D - 0A 20 20 20 20 20 20 20 |rdns |   
+       |
[download]

You can see 0D 0D 0A repeatedly. chcp says cmd.exe is using cp437
cmd.exe and notepad don't show extra newlines.
Is it an actual encoding or just errant output?

Here is a perlio solution

open IN, '-|:raw:crlf', 'ipconfig /?' ...
open OUT', '>:raw' ..
[download]

Comment on ipconfig output encoding ( 0D 0D 0A ) Select or Download Code

Replies are listed 'Best First'.
Re: ipconfig output encoding ( 0D 0D 0A ) ("newlines"?) by tye (Sage) on Feb 09, 2008 at 07:03 UTC
notepad don't show extra newlines Because there aren't any extra newlines. There is an extra carriage return. Probably just somebody wrote `print "...\r\n";` for whatever reason and the Win32 C RTL layer turned "\n" into "\r\n" giving "\r\r\n". Just another reason to ignore trailing whitespace on the ends of lines. Use `s/\s+$//;` instead of chomp. It makes for better-behaved programs. - tye	[reply] [d/l] [select]
Re: ipconfig output encoding ( 0D 0D 0A ) by GrandFather (Saint) on Feb 09, 2008 at 06:51 UTC
A bug in ipconfig is my guess. If you try the same thing with dir the line ends are fine which pretty much precludes cmd trashing the line ends. You could do the cleanup with: `ipconfig /? \| perl -np -e "$_ =~ s![\x0d\x0a]!!gm;" -e "$_ .= qq(\n);" + \| hexdump` [download] Perl is environmentally friendly - it saves trees	[reply] [d/l]
Re: ipconfig output encoding ( 0D 0D 0A ) by jrtayloriv (Pilgrim) on Feb 09, 2008 at 06:48 UTC
EDIT: oops! Not paying attention ...	[reply]