Execute a bash function every 5 seconds but let the rest of the script run

Question

I have a script where i need to run a spicific function at certian intervals while the rest of the script executes normally.

For example... I want to get disk data every hour while the rest of the scripts gathers process data every second...

Here I have a basic script to test this but its not working as expected...

#!/bin/bash

function test () {
echo "This line should print all the time..."
}

function test2 () {
echo "This line should only print every 3 seconds..."
sleep 3
}

while :
do 
   test &
   test2
done

Any help would be.... helpful :-D

Thanks!

Answer 1

Create a function with an infinite loop and a sleep, and start it in the background. It will periodically do stuff, while the rest of the script can continue.

periodic() {
    while :; do
        echo periodic
        date
        sleep 3
    done
}

main() {
    echo in the main...
    sleep 5
    echo still in the main...
    sleep 1
    echo in the main in the main in the main
}

periodic &
periodic_pid=$!

echo periodic_pid=$periodic_pid
main

echo time to stop
kill $periodic_pid

Answer 2

Run the periodic function in a background loop and use sleep to wait 3 seconds between iterations. If you need something done in the context of the main process, send it a signal from the background loop. Don't forget to kill your background processes at exit.

#!/bin/sh
terms=0
trap ' [ $terms = 1 ] || { terms=1; kill -TERM -$$; };  exit' EXIT INT HUP TERM QUIT 

#In case the periodic stuff needs to run in the ctx of the main process
trap 'echo "In main ctx"' ALRM 


test() {
echo "This line should print all the time..."
}

test2__loop()
{
    while :; do
        echo "This line should only print every 3 seconds..."
        kill -ALRM $$
        sleep 3
    done
}


test2__loop &
while :
do 
   test 
   sleep 1
done