BBxM revB - GPIO

I’m using UART2 through Expansion Connector Signals:
UART2_CTS PIN4
UART2_RTS PIN10
UART2_RX PIN8
UART2_TX PIN6

I can see many other GPIO available (P17,…)… How can I use it from bash to send/receive data?

Thx!

root@BBxM:/sys/class/gpio# ls -l