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© Rakhesh Sasidharan

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%TEMP% environment variable has a \2 or other number after it

For my XenApp servers I had set the TEMP and TMP environment variables via GPO to be the following: %USERPROFILE%\AppData\Local\Temp. But that seems to be ignored as all my users were getting these variables set to %USERPROFILE%\AppData\Local\Temp\2 or some similar number. Weird!

Reason for that is that there are 4 different contexts where a variable is set. I knew two of these and kind of knew the third of these, but I had no idea of the fourth one. These four contexts are:

  1. System variable – a variable that applies to all users of the system. These are stored at HKLM\System\CurrentControlSet\Control\Session Manager\Environment.
  2. User variable – a variable that applies to the currently logged in user. These are stored at HKCU\Environment.
  3. Process variable – a variable that you can apply to a particular process and its children. These are not stored in the registry. I kind of knew of such variables (though I hadn’t formalized them in my head) coz I knew you could launch a process and put a variable assignment before it to set the variable just for that process and its children. (Hmm, now that I think about it was that for Linux or Windows?)
  4. Volatile variable – a variable that applies to the current context of the currently logged in user. These are not saved between log offs or reboots. They are stored at HKCU\VolatileEnvironment.

Whoa! So volatile variables. I had no idea of these, but sure enough when I checked the registry location TEMP and TMP were set there just like I was seeing.

(All the above info was from this helpful TechNet page by the way).

I had no idea a single user could have multiple sessions open on a machine. Server or desktop, I was under the impression you were restricted to a single session; but I guess I was mistaken. From a forum post:

This concept was originally was created by Citrix when they produced WinFrame as a way of handling multiple user sessions on the same machine as a way to handle keeping each user’s temp location unique to each user. Microsoft added it to their OS subsequently as they added Windows Terminal Services to the OS, and this only happened when logging into a terminal services session.

With the evolution of the OS in the Vista timeframe, Micrsooft added the ability for you to have multiple users logged into the OS console at the same time and switch between user sessions, to do that they used the same concept borrowed from the Windows Terminal Services side of the OS.

It is just a mechanism to keep the temp variable locations unique and separate between users. The number used for the directory is actually the session ID number for the user session.

Anyhow, what can I do to fix this? Turns out we can disable this multiple TEMP folders per session thing via GPO. The relevant setting is under: Windows Components/Remote Desktop Services/Remote Desktop Session Host/Temporary folders. Here I set “Do not use temporary folders per session” to true and now I don’t have multiple TEMP folders. Since I don’t want separate sessions (mainly coz I don’t know what they are used for in terms of XenApp) I also went ahead and disabled that from Windows Components/Remote Desktop Services/Remote Desktop Session Host/Connections where you can find a setting called “Restrict Remote Desktop Services users to a single Remote Desktop Services session”.