File /etc/rc.local Edit the file with the command (add at the end of the file, just BEFORE exit 0)

sudo nano /etc/rc.local

#CONFIGURATION PORT PTT & SQL
 
# Radio "VHF" GPIO 16:PTT - GPIO 19:SQUELCH
echo "16" > /sys/class/gpio/export &
sleep 2
echo out > /sys/class/gpio/gpio16/direction
 
echo "19" > /sys/class/gpio/export &
sleep 2
echo in > /sys/class/gpio/gpio19/direction
sleep 2
echo 1 >  /sys/class/gpio/gpio19/active_low  
# MODE A : Squelch is active when the signal from receiver come from 0V to +5V (or 0V => +x V) / Upper config 'active_low' line is NOT in the script (line commented with # at its begin)
# MODE B : Squelch is active when the signal from receiver come from +5V to 0V (or +xV => 0V ) / Upper config 'active_low' line is in the script (uncommented)
 
 
# Radio "LINK" GPIO 17:PTT - GPIO 18:SQUELCH
echo "17" > /sys/class/gpio/export &
sleep 2
echo out > /sys/class/gpio/gpio17/direction
 
echo "18" > /sys/class/gpio/export &
sleep 2
echo in > /sys/class/gpio/gpio18/direction
sleep 2
echo 1 >  /sys/class/gpio/gpio18/active_low
# MODE A : Squelch is active when the signal from receiver come from 0V to +5V (or 0V => +x V) / Upper config 'active_low' line is NOT in the script (line commented with # at its begin)
# MODE B : Squelch is active when the signal from receiver come from +5V to 0V (or +xV => 0V ) / Upper config 'active_low' line is in the script (uncommented)
 

It is possible to test the configuration that way [http://wiringpi.com/ wiringPi].

The result must be conform with (instruction gpio readall):