Usage of File::Spec->devnull() on Windows

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

I was attempting to use the following code from Archive:Zip examples on Windows:

# Example of how to compute compressed sizes
# $Revision: 1.2 $
use strict;
use Archive::Zip qw(:ERROR_CODES);
require File::Spec::Win32;
my $zip = Archive::Zip->new();
my $blackHoleDevice = File::Spec::Win32->devnull();

$zip->addFile($_) foreach (<*.pl>);

# Write and throw the data away.
# after members are written, the writeOffset will be set
# to the compressed size.
$zip->writeToFileNamed($blackHoleDevice);

my $totalSize = 0;
my $totalCompressedSize = 0;
foreach my $member ($zip->members())
{
    $totalSize += $member->uncompressedSize;
    $totalCompressedSize += $member->_writeOffset;
    print "Member ", $member->externalFileName,
    " size=", $member->uncompressedSize,
    ", writeOffset=", $member->_writeOffset,
    ", compressed=", $member->compressedSize,
    "\n";
}

print "Total Size=", $totalSize, ", total compressed=", $totalCompress
+edSize, "\n";

$zip->writeToFileNamed('test.zip');
[download]

However, while it worked on Linux, OSX, it was a failure on Windows. BTW: while stepping through the debugger i saw that the scalar $blackHoleDevice was set to 'nul' not the usual Windows /dev/null device 'NUL'. However even it it was then set to 'NUL' it still did not work. When $blackHoleDevice was replaced by an actual file name it worked fine, but one assumes that the use of /dev/null was used to avoid the actual creation of a file. Question: is this just windows or me?

Comment on Usage of File::Spec->devnull() on Windows Download Code

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Re: Usage of File::Spec->devnull() on Windows by tobyink (Canon) on Jul 30, 2012 at 16:27 UTC
Hmmm... interesting. Sorry I don't have the answer, but I can offer a workaround. Archive::Zip supports `writeToFileHandle` as an alternative to `writeToFileNamed`. You can probably pass it something other than a real filehandle, like maybe an IO::Null object. `perl -E'sub Monkey::do{say$_,for@_,do{($monkey=[caller(0)]->[3])=~s{::}{ }and$monkey}}"Monkey say"->Monkey::do'`	[reply] [d/l] [select]
Re^2: Usage of File::Spec->devnull() on Windows by chazubell (Beadle) on Aug 02, 2012 at 16:28 UTC
Thanks. To all. I will try writing to a file handle.	[reply]
Re: Usage of File::Spec->devnull() on Windows by chazubell (Beadle) on Jul 30, 2012 at 16:25 UTC
I just found my own answer. The /dev/null device on windows is now `NIL` OOPS.	[reply] [d/l]
Re^2: Usage of File::Spec->devnull() on Windows by BrowserUk (Patriarch) on Jul 30, 2012 at 20:17 UTC
The /dev/null device on windows is now NIL That is not true. The nul device on wihdows is any file with a name that (without any extension) equals 'nul' in any case. Ie nul, NUL nUl, Nul; NUL.TXT, nul.TXT, NUl.tXt, nul.exe, .\nul, .\..\cwd\fred\..\nul.asmanycharactersafterthedotasyoucaretoadd C:\test>md newdir C:\test>cd newdir C:\test\newdir>echo . > NIL C:\test\newdir>dir 30/07/2012 21:06 <DIR> . 30/07/2012 21:06 <DIR> .. 30/07/2012 21:06 4 NIL 1 File(s) 4 bytes 2 Dir(s) 101,782,999,040 bytes free C:\test\newdir>echo . > NUL C:\test\newdir>echo . > nul C:\test\newdir>echo . > NuL C:\test\newdir>echo . > ./../newdir/nul C:\test\newdir>echo . > nulpoint C:\test\newdir>echo . > nul.txt C:\test\newdir>echo . > nul.exe C:\test\newdir>echo . > c:\test\newdir\nul.1231243345345 C:\test\newdir>dir Volume in drive C has no label. Volume Serial Number is 8C78-4B42 Directory of C:\test\newdir 30/07/2012 21:07 <DIR> . 30/07/2012 21:07 <DIR> .. 30/07/2012 21:06 4 NIL 30/07/2012 21:07 4 nulpoint 2 File(s) 8 bytes 2 Dir(s) 101,783,220,224 bytes free [download] With the rise and rise of 'Social' network sites: 'Computers are making people easier to use everyday' Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error. "Science is about questioning the status quo. Questioning authority". In the absence of evidence, opinion is indistinguishable from prejudice. The start of some sanity?	[reply] [d/l]
Re^2: Usage of File::Spec->devnull() on Windows by moritz (Cardinal) on Jul 30, 2012 at 16:54 UTC
Several resources suggest that `NUL` is a reserved file name, not `NIL`. I don't have a windows at hand to test it, but I'd guess it's actually NUL that is equivalent to UNIX' /dev/null. Perl 6 - the future is here, just unevenly distributed	[reply] [d/l] [select]
Re^2: Usage of File::Spec->devnull() on Windows by MidLifeXis (Monsignor) on Jul 30, 2012 at 16:54 UTC
Do you have a reference for that? I am not able to verify that this is the case. If it is, ouch (unnecessary backward compatible breakage). In fact, my testing from a Windows 7 cmd prompt and perl script seem to disprove your assertion. --MidLifeXis	[reply]