Check if Windows batch variable starts with a specific string

to find batch file location use %0 (gives full patch to current batch file) or %CD% variable which gives local directory

Use the variable substring syntax:

IF "%variable:~0,3%"=="ABC" [...]

If you need the path to the batch file without the batch file name, you can use the variable:

%~dp0

Syntax for this is explained in the help for the for command, although this variable syntax extends beyond just the for command syntax.