PowerShell: Passing PS Variables to Batch Files

I couldn't find many easy ways to transfer variables from PowerShell to cmd.exe batch files so I came up with my own solution.  We delete the old temp variable holding file, use PowerShell to create the variable and write the output to a go-between batch file, call that go-between batch file from your original batch file, and use the transferred variable.  Let me know if you don't get it, have questions, or have better suggestions:

1. Delete the variable-holding batch file from the last time it was used:
If exist d:\computername.bat del d:\computername.bat >nul

2.  From your batch file, create your PowerShell variable (I wanted to pick up the computer name):

powershell "$ComputerName = ('HQ-' + (gwmi win32_systemenclosure).SMBIOSAssetTag);write ('set PC=' + $computername)|out-file d:\computername.bat -encoding ASCII"

Note: In your new computername.bat file you have:
Set PC=HQ-R0xxxx
Which is a valid DOS batch command to create a variable named PC.

3. By writing the results into a batch file (computername.bat), you can call the new batch file from your original one.  Also, by writing a batch command to set a DOS variable, you've now transferred your PowerShell variable to a batch file.  From your original script:
call d:\computername.bat

4.  Now you can use the %PC% variable in your DOS batch file without having to load PowerShell each time you want to pull up the variable.  Obviously you can create all your variables from one PowerShell instance and have the command write out all the Set commands.

Also note, most systems have a restrictive PowerShell script execution policy so writing PS one-liners makes them easier to run since you don't have to worry about the script policy.

Example Batch File:


@Echo Off
if exist d:\computername.bat del d:\computername.bat >nul
PowerShell "$ComputerName = ('HQ-' + (gwmi win32_systemenclosure).SMBIOSAssetTag);write ('set PC=' + $computername)|out-file d:\computername.bat -encoding ASCII"
call d:\computername.bat
:InstallImage
cls
Echo.
Echo                               MAIN IMAGING MENU (%PC%)
Echo.
...