Reading from the Windows registry in Perl

Question

I try to get the installation location of the program without checking a number of hard-coded paths, hoping to get them from the path stored in the Windows registry, but I get empty return values ​​or error messages when I try to read the required key values.

I read about Parsing windows registry using Perl , and I think I included all the answers in my script, but I always get an empty result when I try to read the registry value, even if you run from an elevated command prompt to make sure that the script has administrator rights.

At first I tried to use Win32 :: TieRegistry, and as mentioned, the return value is empty, so I tried just to bypass and use reg query , but this gives an error in that the key was not found. Running the same reg query command outside of Perl successfully reads the key. What am I doing wrong?

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Update. The main reason (indicated in the pair's responses received) was trying to access the 64-bit registry representation from 32-bit Perl ; by default, any 32-bit Windows application is redirected to HKLM\Software\WOW6432Node when trying to access the HKLM\Software keys, so I need to find a way to avoid this, since my interesting key does not exist in this place.

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Perl script:

 #!/usr/bin/perl -w use strict; use Data::Dumper; use Win32::TieRegistry (Delimiter => '/'); my $mykey = $Registry->{'HKEY_LOCAL_MACHINE/Software/ikv++ technologies ag/medini unite (x64)'}; my $mykeyval = $mykey->{'/Path'}; print " value=$mykeyval\n"; print Dumper $mykey; my $sysCmd =`reg query "HKLM\\Software\\ikv++ technologies ag\\medini unite (x64)" /v Path`; print " sysCmd=$sysCmd\n"; 

Output:

 C:\Users\username\AppData\Local\Temp>perl test_reg_read.pl Use of uninitialized value in concatenation (.) or string at test_reg_read.pl line 9. value= $VAR1 = {}; ERROR: The system was unable to find the specified registry key or value. sysCmd= 

reg query command outside Perl:

 C:\Users\username\AppData\Local\Temp>reg query "HKLM\Software\ikv++ technologies ag\medini unite (x64)" /v Path HKEY_LOCAL_MACHINE\Software\ikv++ technologies ag\medini unite (x64) Path REG_SZ C:\Program Files\ikv++ technologies ag\mediniUnite 

Note that all this is done from an elevated command prompt; as soon as he works there, I was going to experiment with necessity.

Answer 1

As mentioned in Srgrn's answer, the problem is that my Perl is 32-bit, running on a 64-bit system. Windows automatically redirects 32-bit processes to the Wow6432Node node registry when accessing HKLM\Software , unless specifically instructed to use 64-bit or 32-bit registry views with the access mode flag .

I could specify access with the old Win32API :: Registry , but instead I decided to specify access mode with the TieRegistry object's Functions :

 #!/usr/bin/perl -w use strict; use Win32::TieRegistry (Delimiter => '/'); print "explicitly access 64-bit location:\n"; my $mykey = new Win32::TieRegistry 'HKEY_LOCAL_MACHINE/Software/ikv++ technologies ag/medini unite (x64)', { Access=>Win32::TieRegistry::KEY_READ()|0x0100, Delimiter=>'/' }; my $mykeyval = $mykey->GetValue('Path'); print " value=$mykeyval\n"; print " Values are: "; print join(', ', $mykey->ValueNames); print "\n"; print "explicitly access 32-bit location:\n"; $mykey = new Win32::TieRegistry 'HKEY_LOCAL_MACHINE/Software/ikv++ technologies ag/medini unite', { Access=>Win32::TieRegistry::KEY_READ()|0x0200, Delimiter=>'/' }; $mykeyval = $mykey->GetValue('Path'); print " value=$mykeyval\n"; print " Values are: "; print join(', ', $mykey->ValueNames); print "\n"; 

This gives the expected results for both 32-bit and 64-bit keys, and should also work the same in both 32-bit and 64-bit Perl (theoretically, one way or another).

Note. I needed to specify the full namespace for the KEY_READ () function in my version of Perl to prevent compilation errors, and I'm not sure if there are named values ​​for the constants 0x0100 and 0x0200, so this may be coarser than necessary for some systems but it seems to work great for me!

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Note. It also allows you to read the correct key version with the same name in either the 32-bit or 64-bit version , so this answer is duplicated.

Answer 2

you use 64-bit OS and 32-bit pearls, which means that when you start from perl, you actually get the values ​​in the WOW6432Node, and not behind the keys you want

you need to use 64 bit perl.

for example from my own car

 λ c:\Strawberry\perl\bin\perl my $sysCmd = `reg query "HKLM\\SOFTWARE\\VMware, Inc.\\VMware Drivers" /v vmci.status`; print $sysCmd; ^D ERROR: The system was unable to find the specified registry key or value. λ c:\Strawberry\perl\bin\perl my $sysCmd = `reg query "HKLM\\SOFTWARE\\VMware, Inc.\\VMware USB" /v InstallPath`; print $sysCmd; ^D HKEY_LOCAL_MACHINE\SOFTWARE\VMware, Inc.\VMware USB InstallPath REG_SZ C:\Program Files (x86)\Common Files\VMware\USB\ 

where "HKEY_LOCAL_MACHINE \ SOFTWARE \ VMware, Inc. \ VMware USB" is located in WOW6432Node, but there are no drivers.

this affects both the command executed with perl and the module.

[Edit for completeness] apperantly there is a way to get 64-bit keys from 32-bit perl, as shown at the bottom of the discussion at http://www.perlmonks.org/?node_id=1007098