提示如图:

➜ fastboot flash recovery twrp-3.3.1-0-santoni.img
< waiting for any device >

命令加上sudo即可

➜ sudo fastboot flash recovery twrp-3.3.1-0-santoni.img
[sudo] password for cnbattle:         
target reported max download size of 535822336 bytes
sending 'recovery' (24844 KB)...
OKAY [  0.968s]
writing 'recovery'...
OKAY [  0.323s]
finished. total time: 1.292s