Detecting installed programs via registry

Question

Hi there,

I need to develop a process that will detect if the users computer has certain programs installed and if so, what version. I believe I will need a list with the registry location and keys to look for and feed it to the program which is not a problem. Is there a better way to accomplish this?

My first thought was to check in the registry in the uninstallation entries but it seems one of the apps I wish to detect does not have one. What is the standard location for all registry using applications to make an entry in?

Answer 1

Seems like looking for something specific to the installed program would work better, but HKCU\Software and HKLM\Software are the spots to look.

Answer 2

Look around here: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall

There are the most programms listed.

Look at key's: DisplayName DisplayVersion

last is not always set!

on 64bit systems the x86 key is: HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall x64 key is the first one.

Answer 3

You could use MSI API to enumerate everything installed by Windows Installer but that won't list all the software available on a machine. Without knowing more about what you need I think the concept of "installed" is a little vague. There are many ways to deploy software to a system ranging from big complicated installers to ZIP files and everything in between.

Answer 4

User-specific settings should be written to HKCU\Software, machine-specific settings to HKLM\Software. Under these keys, structure [software vendor name]\[application name] (e.g. HKLM\Software\Microsoft\Internet Explorer) may be the most common, but that's just a convention, not a law of nature.

Many (most?) applications also add their uninstall entries to HKLM\Software\Microsoft\Windows\CurrentVersion\Uninstall\[app name], but again, not all applications do this.

These are the most important keys; however, contents of the registry do not have to represent the installed software exactly - maybe the application was installed once, but then was manually deleted, or maybe the uninstaller didn't remove all traces of it. If you want to be sure, check the filesystem to see if the application still exists where its registry entries say it is.

Answer 5

An application does not need to have any registry entry. In fact, many applications do not need to be installed at all. U3 USB sticks are a good example; the programs on them just run from the file system.

As noted, most good applications can be found via their uninstall registry key though. This is actually a pair of keys, per-user and per-machine (HKCU/HKLM - Piskvor mentioned only the HKLM one). It does not (always) give you the install directory, though.

If it's in HKCU, then you have to realise that HKEY_CURRENT_USER really means "Current User". Other users have their own HKCU entries, and their own installed software. You can't find that. Reading every HKEY_USERS hive is a disaster on corporate networks with roaming profiles. You really don't want to fetch 1000 accounts from your remote [US|China|Europe] office.

Even if an application is installed, and you know where, it may not have the same "version" notion you have. The best source is the "version" resource in the executables. That's indeed a plural, so you have to find all of them, extract version resources from all and in case of a conflict decid on something reasonable.

So - good luck. There are dozes of ways to fail.

Answer 6

Registry? Best bet, is to use WMI (Win32_Product).

Answer 7

Win32_Product never shows everything, only software installed via an MSI installer (as far as I can tell.)

There are lots of software packages that get installed via other installers that don't show up in there. another way is needed.