Shell script to toggle LEDs on a MCP23017 I2C I/O expander connected to a pine64 board

pine64-i2c-MCP23017-toggleLeds.sh

#!/bin/bash

#elevate to root to ensure no permission errors
#[ `whoami` = root ] || exec su -c $0 root
if [[ $EUID -ne 0 ]]; then
  echo "i2cset usually needs sudo powers to run, please login if prompted to avoid permission errors"
  exec sudo $0
fi

echo "Set all Port A pins (GPA0-7) as outputs..."
i2cset -y 1 0x20 0x00 0x00

echo "Ensuring all outputs are off..."
i2cset -y 1 0x20 0x14 0x00

echo "Toggling LED 1 (GPA0)"
i2cset -y 1 0x20 0x14 0x01
sleep 1
i2cset -y 1 0x20 0x14 0x00
sleep 1

echo "Toggling LED 2 (GPA1)"
i2cset -y 1 0x20 0x14 0x02
sleep 1
i2cset -y 1 0x20 0x14 0x00
sleep 1

echo "Toggling LED 3 (GPA2)"
i2cset -y 1 0x20 0x14 0x04
sleep 1
i2cset -y 1 0x20 0x14 0x00
sleep 1

echo "Toggling LED 4 (GPA3)"
i2cset -y 1 0x20 0x14 0x08
sleep 1
i2cset -y 1 0x20 0x14 0x00
sleep 1

echo "Toggling LED 5 (GPA4)"
i2cset -y 1 0x20 0x14 0x10
sleep 1
i2cset -y 1 0x20 0x14 0x00
sleep 1

# Below lines commented as only used five leds in demo due to breadboard space
#echo "Toggling LED 6 (GPA5)"
#i2cset -y 1 0x20 0x14 0x20
#sleep 1
#i2cset -y 1 0x20 0x14 0x00
#sleep 1

#echo "Toggling LED 7 (GPA6)"
#i2cset -y 1 0x20 0x14 0x40
#sleep 1
#i2cset -y 1 0x20 0x14 0x00
#sleep 1

#echo "Toggling LED 8 (GPA7)"
#i2cset -y 1 0x20 0x14 0x80
#sleep 1
#i2cset -y 1 0x20 0x14 0x00
#sleep 1

echo "All done!"