# get-GetTempFileName.ps1
# Creates a uniquely named, zero-byte file in the temp dir
# Thomas Lee - tfl@psp.co.uk 

# Get file name (and create the file!):
$fn1 = [system.io.path]::GetTempFileName()

# Display Results
"File name returned: $fn1"
ls $fn1

# delete the file
Del $fn1

PSH [C:\foo]: .\get-tempfilename.ps1
File name returned: C:\Documents and Settings\tfl\Local Settings\Temp\tmp6A.tmp


    Directory: Microsoft.PowerShell.Core\FileSystem::C:\Documents and Settings\tfl\Local Settings\Temp


Mode                LastWriteTime     Length Name
----                -------------     ------ ----
-a---         7/13/2008   7:41 PM          0 tmp6A.tmp


PSH [C:\foo]:

In low rights environments e.g. in some ASP.NET configurations, this function will fail with a security exception. That's because it needs to find the temp directory and that's reading the "Environment".

The exception stack shows that this method calls Path.GetTempPath which requires:

• EnvironmentPermission
for unrestricted access to environment variables. Associated enumeration: PermissionState.Unrestricted