I am running the following command within a batch script:

```
netsh advfirewall firewall show rule name ="MyCustomRule"

```

And it gives out either a string "No rules match the specified criteria." or multiple rows.

I would like to be able to assign its output to a variable something like:

```
set a = output(netsh advfirewall firewall show rule name ="MyCustomRule")

```

Such that I can further do `if "%a%" == ""` . Is it possible?