Checking Android's Currently Active Partition Slot

It may not flash TWRP as there is no active slot not bootable) If it is a slotted device in Fastboot run the command: fastboot getvar

So i decided to flash twrp into a boot slot via fastboot then, i set the active-slot to that but then I still don't get twrp idk why Now, I can get into

fastboot_ error_ failed to identify current slot active slot back However, I didn't know which partition slot was currently active A couple

fastboot getvar currentslot Android phones can now have an A and a B partition system for the OS and we can use this fastboot command to check and see which slot is currently active