cmd-dat

test

set "aaa=bbb"
echo %aaa%
bbb

set "conf=D:\arduino-1.8.19-windows\arduino-1.8.19\hardware\tools\avr\etc\avrdude.conf"

set "ad=D:\arduino-1.8.19-windows\arduino-1.8.19\hardware\tools\avr\bin\avrdude.exe"
%ad%

%ad% -C %conf%