Checking Android's Currently Active Partition Slot

Checking Android's Currently Active Partition Slot fastboot get active slot I am trying to root my Xiaom mi a2 phone But i am stuck on changing the active partition When i enter fastboot set_active b it doesnt fastboot_ error_ failed to identify current slot I was able to fix this with fastboot --set-active=a followed immediately by fastboot flash boot and all the other partitions

fastboot_ error_ failed to identify current slot Flash all partitions from $ANDROID_PRODUCT_OUT On AB devices, flashed slot is set as active Secondary images may be flashed to inactive slot

fastboot change slot But I want without fastboot command My usecase is the bootloader need to check the currect active slot and set the proper suffix How can I do On AB devices, flashed slot is set as active Secondary images may be flashed to inactive slot flash PARTITION Flash given partition, using the