Question

I’m trying to write a perl script that determines which users are currently logged into Windows by using query.exe (c:\Windows\system32\query.exe). Perl is unable to access this file, unable to execute it, even unable to see that it exists, as I’ve found with the following code:

print `dir c:\\windows\\system32\\query*`;

This produces the following output:

07/13/2009  05:16 PM         1,363,456 Query.dll
1 File(s)      1,363,456 bytes
0 Dir(s)  183,987,658,752 bytes free

I’ve checked the user executing the script using perl’s getlogin function, and it returns the name of a member of the local Administrators group (specifically, me). I’ve also tried adding read/execute permissions for “Everyone”, but windows keeps giving me access denied errors when I try to modify this file’s permissions. Finally, I’ve tried running perl.exe as an administrator but that doesn’t fix the problem either.

Is this something I can solve by changing some settings in Windows? Do I need to add something to my perl script? Or is there just no way to grant perl access to some of these processes?

Answer 1

On my 64 bit machine I can find query.exe in Windows\System32 (the 64 bit system directory) but not in Windows\SysWOW64 (the 32 bit system directory).

I suspect that you are running 64 bit Windows and 32 bit Perl and so, under WOW64 emulation, the 32 bit Perl process redirects system32 to SysWOW64.

Since system32 should be in your path you ought to be able to execute it by executing query.exe without any path. If you absolutely have to refer to the 64 bit system folder then you can do so from a 32 bit process with C:\Windows\sysnative.

If my suspicions are correct I recommend you do some reading up on WOW64 because it can be pretty confusing until you get on top of it. On the other hand, if you already know all about it I apologise for being patronising.