Opening and Reading Registry Values
Let’s start our exploration of the Registry by finding out how to get information out of it. As an example, let’s see what we can find out about the current build version of Windows NT on our system. If you’re using this book on a Windows 95 system, you’ll need to change the Windows NT key to Windows:
use Win32::Registry; $p = "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion"; $main::HKEY_LOCAL_MACHINE->Open($p, $CurrVer) || die "Open: $!"; $CurrVer->GetValues(\%vals); # get sub keys and value -hash ref foreach $k (keys %vals) { $key = $vals{$k}; print "$$key[0] = $$key[2]\n"; # see below for explanation }
Running this script on one of our systems produces the following output:
CurrentBuildNumber: 1381 CSDVersion = Service Pack 3 CurrentBuild = 1.511.1 () (Obsolete data - do not use) RegisteredOrganization = Axiom Technologies CurrentType = Uniprocessor Free InstallDate = Ö?L3 RegisteredOwner = Erik Olson CurrentVersion = 4.0 SystemRoot = D:\NT CurrentBuildNumber = 1381 SoftwareType = SYSTEM ProductId = 50036419013877247607 SourcePath = E:\I386 PathName = D:\NT
Let’s see what’s going on here. The first line of the
script employs the use
operator to include the
Win32::Registry
package. We then have a variable
$p
containing a Registry path relative to
HKEY_LOCAL_MACHINE
. The third line uses
$main::HKEY_LOCAL_MACHINE
(one of the Registry
keys declared in registry.pm that we mentioned)
to open the CurrentVersion
key. If the
Open
method succeeds,
Get Learning Perl on Win32 Systems now with the O’Reilly learning platform.
O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.