Running Bash Shell Script continuously from boot at background. (Raspberry Pi)

Question

So I want to run this script continuously in background. I was able to start it at boot and then run it, but it stops running after sometime. Whats wrong?

#!/bin/sh

### BEGIN INIT INFO
# Provides:          myfirst
# Required-Start:    $network
# Required-Stop:    
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: myfirst
# Description:       Speaker switch 
### END INIT INFO


echo "18" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio18/direction

while true;do
        ps cax | grep hairtunes > /dev/null
        if [ $? -eq 0 ]; then
        echo "0" > /sys/class/gpio/gpio18/value
        else
        echo "1" > /sys/class/gpio/gpio18/value
        fi
        sleep 5
done

exit 0

Answer 1

You shouldn't run while loop inside initscript. Init will kill long-running initscripts. You can extract all logic

echo "18" > /sys/class/gpio/export
echo "out" > /sys/class/gpio/gpio18/direction

while true;do
        ps cax | grep hairtunes > /dev/null
        if [ $? -eq 0 ]; then
        echo "0" > /sys/class/gpio/gpio18/value
        else
        echo "1" > /sys/class/gpio/gpio18/value
        fi
        sleep 5
done

into separate scrip and run it with & from initscipt. Like this:

#!/bin/sh

### BEGIN INIT INFO
# Provides:          myfirst
# Required-Start:    $network
# Required-Stop:    
# Default-Start:     2 3 4 5
# Default-Stop:      0 1 6
# Short-Description: myfirst
# Description:       Speaker switch 
### END INIT INFO

case "$1" in
  start)
    /path/to/the/script/above/with/logic.sh &
    ;;
  stop)
    # you need to store pid to do this 
    ;;
  *)
    echo "Usage: $0 {start|stop}"
    exit 1
    ;;
esac

This should work. However, this isn't a best solution. The best one is to correctly demonize you process which is somewhat different topic.