On Windows, how do I set an environment variable for a user other than the currently logged in one? I need to set the TMP variable to change the temporary directory used by an ASP.NET app.

  • As an unrelated comment: Why in the world would an ASP.NET application look to the computers Env. variables for a file path setting? AppSettings are built-in for that reason alone. Commented Jun 12, 2012 at 16:48
  • Also, this question is off topic for ServerFault, it should be posted on SuperUser Commented Jun 12, 2012 at 16:51
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    @BrentPabst - The standard temp directory api in .Net reads from it - msdn.microsoft.com/en-us/library/… Commented Jun 12, 2012 at 18:26
  • Right, so what user is your application running under? Does it change that context each time a user logs in? Typically in IIS this is not the logged in user. Commented Jun 12, 2012 at 22:10
  • @BrentPabst - I don't get what you're getting at. It runs under the same context every time (Network Service). But rather than setting the TMP variable for the entire server, I want to set it just for that user. I think what uSlackr recommends is going to work. Are you proposing another approach? Commented Jun 13, 2012 at 12:46

1 Answer 1


You can access through the registry. Modify the \Environment\Tmp key in HKEY_Users\<their SID>

Here are two solutions for getting the account SID

$User = New-Object System.Security.Principal.NTAccount("domainname", "username") 
$SID = $User.Translate([System.Security.Principal.SecurityIdentifier]) 


Get-WmiObject win32_useraccount -Filter "name = 'username' AND domain = 'domainname'"
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    Inspired by this answer, I was able to figure out how to do this via Chef. Commented Feb 9, 2015 at 0:12
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    Is there an elegant way to get the SID of a user?. Particularly a virtual account?.
    – Beau Trepp
    Commented Sep 15, 2015 at 3:01
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    You could ask that as another question, but if you do a google search for get sid of application pool identity, the first result, winterdom.com/2014/05/iis-apppool-identity-sids, has a pretty elegant solution.
    – austinian
    Commented Sep 25, 2015 at 10:08
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    @austinian That link is now unavailable. That's why it's important to include such information in an answer itself, instead of linking to it.
    – Stijn
    Commented Dec 21, 2017 at 17:25
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    This powershell code will grab the SID $User = New-Object System.Security.Principal.NTAccount("domain", "username") $SID = $User.Translate([System.Security.Principal.SecurityIdentifier]) $SID.Value or Get-WmiObject win32_useraccount -Filter "name = 'user' AND domain = 'domain'"
    – uSlackr
    Commented Dec 22, 2017 at 18:10

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