How to use a PowerShell function return as a variable in a batch file - powershell

Question

I was trying to use the return from myPowershellScript.ps1 to use as a variable in my batch file.
myPowershellScript.ps1
function GetLatestText
{
return "Hello World"
}
I was trying to use the For /F function. There may be a better way.
myBatch.bat
for /f "delims=" %%a in (' powershell -command "\\Rossi2\Shared\myPowershellScript.ps1" ') do set "var=%%a"
echo %var%
Desired output, would be to have 'Hello World' output in the cmd window.
I was trying to use the batch file as some old processes use them. For newer processes I do everything in PowerShell and it works fine.
The current output is blank.

Answer 1

Your syntax for trying to capture output from a PowerShell script from a batch file is correct (assuming single-line output from the script),[1] except that it it is more robust to use the -File parameter of powershell.exe, the Windows PowerShell CLI than the -Command parameter.
See this answer for when to use -File vs. -Command.
Your problem is with the PowerShell script itself:
You're defining function Get-LatestText, but you're not calling it, so your script produces no output.
There are three possible solutions:
Place an explicit call to Get-LatestText after the function definition; if you want to pass any arguments received by the script through, use Get-LatestText #args
Don't define a function at all, and make the function body the script body.
If your script contains multiple functions, and you want to call one of them, selectively: in your PowerShell CLI call, dot-source the script file (. <script>), and invoke the function afterwards (this does require -Command):
for /f "delims=" %%a in (' powershell -Command ". \"\\Rossi2\Shared\myPowershellScript.ps1\"; Get-LatestText" ') do set "var=%%a"
echo %var%
[1] for /f loops over a command's output line by line (ignoring empty lines), so with multiline output only the last line would be stored in %var% - more effort is needed to handle multiline output.

Answer 2

You can combine the batch and the powershell in single file (save this as .bat ):
<# : batch portion
#echo off & setlocal
for /f "tokens=*" %%a in ('powershell -noprofile "iex (${%~f0} | out-string)"') do set "result=%%a"
echo PS RESULT: %result%
endlocal
goto :EOF
: end batch / begin powershell #>
function GetLatestText
{
return "Hello World"
}
write-host GetLatestText