所以我需要使用'/dev/ttyACM0'。我尝试显示所有可用的 USB 选项：
~$ sudo dmesg | grep tty，我得到
[ 0.098062] printk: console [tty0] enabled
[ 291.890275] cdc_acm 2-1.3:1.0: ttyACM0: USB ACM device
[ 825.280387] cdc_acm 2-1.2:1.0: ttyACM0: USB ACM device
[ 1071.046356] cdc_acm 2-1.2:1.0: ttyACM0: USB ACM device
[ 1143.484587] cdc_acm 2-1.2:1.0: ttyACM0: USB ACM device
[ 1467.838416] cdc_acm 2-1.2:1.0: ttyACM0: USB ACM device
[ 2074.551625] cdc_acm 2-1.2:1.0: ttyACM0: USB ACM device
[ 2137.536720] cdc_acm 2-1.2:1.0: ttyACM0: USB ACM device
[ 2196.153047] cdc_acm 2-1.2:1.0: ttyACM0: USB ACM device
[ 2307.305412] cdc_acm 2-1.2:1.0: ttyACM0: USB ACM device
但当我尝试时sudo chmod -R 777 /dev/ttyACM0，我明白了chmod: cannot access '/dev/ttyACM0': No such file or directory。
为什么明明我有 ttyACM0 却说没有这样的文件或目录？