$ ls -l /dev/serial*

lrwxrwxrwx​ ​1​ ​root​ ​root​ ​5​ ​Nov​ ​21​ ​07:54​ ​/dev/​​serial0​ ​->​ ​ttyS0 lrwxrwxrwx​ ​1​ ​root​ ​root​ ​7​ ​Nov​ ​21​ ​07:54​ ​/dev/serial1​ ​->​ ​ttyAMA0 $ ls - l /dev/ttyS0

crw-rw​----​​1​​root​​dialout​​4,​​64​​Nov​​21​​07:54​​/dev/ttyS0​

$groups

pi​adm​​dialout​​​​cdrom​​​sudo​​audio​​video​​plugdev​​games​​users​​input​​netdev​​gpio​​​​i2c​​​spi​

$sudo grep uart /boot/cmdline.txt

enable_uart=1

$ sudo cat /boot/cmdline.txt

dwc_otg.lpm_enable=0​console=tty1​​​​​​root=PARTUUID (no​more​​exists​​console=ttyS0,115200)​