fastboot commands

Android fastboot 查詢當前使用的ab槽 fastboot get active slot It means fastboot is waiting for a phone to be connected If the phone is physically connected but fastboot cannot find it, then either the fastboot getvar currentslot It means fastboot is waiting for a phone to be connected If the phone is physically connected but fastboot cannot find it, then either the

fastboot_ error_ failed to identify current 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