Simple linux service for brute-force bluetooth auto-connection

readme.md

bluetooth-reconnect

Inspired by bluetooth-autoconnect, but much simplier and actually works. Based on systemd service (daemon) which does the following, repeatedly:

1. Check activation condition. In my case, just check if /dev/something does not exist.
2. Try to run bluetoothctl connect <MAC>. No checks if bluetooth is on, etc. Dead simple.
3. Sleep for delay seconds (configurable).

How to install

// TODO

References

• How test command works: https://www.computerhope.com/unix/test.htm
• How to loop with equal invervals: https://unix.stackexchange.com/a/214660

bluetooth-reconnect

#!/bin/bash

# Miminum delay between iterations, in seconds
delay=10
# Odd index: bluetooth MAC, even index: test expression
targets=(
  "98:B6:E9:47:F0:4F" "test ! -f /dev/input/js0"
  "98:B6:E9:72:6C:31" "test ! -f /dev/whatever"
)

function try_target() {
  if $2
  then
    echo "Target $1 (check: $2) -> check true, trying to connect";
    bluetoothctl connect "$1";
  else
    echo "Target $1 (check: $2) -> check false, skipping"
  fi
}

last_time=$(date +%s)
while true
do
  # seq args: <start> <step> <end>
  for i in $(seq 1 2 ${#targets[@]});
    do try_target "${targets[i-1]}" "${targets[i]}"
  done

  curr_time=$(date +%s)
  elapsed=$((curr_time - last_time))
  loop_delay=$((elapsed>delay ? 0 : (delay-elapsed)))
  echo "Loop finished, sleeping for $loop_delay sec"
  sleep $loop_delay
  last_time=$(date +%s)
done

function try_target() {
  if $2
  then
    echo "Target $1 (check: $2) -> check true, trying to connect...";
    bluetoothctl connect "$1";
  else
    echo "Target $1 (check: $2) -> check false, skipping"
  fi
}

# seq args: <start> <step> <end>
for i in $(seq 1 2 ${#targets[@]});
  do try_target "${targets[i-1]}" "${targets[i]}"
done

echo "All targets processed"

bluetooth-reconnect.service

[Unit]
Description=Bluetooth reconnect service
Before=bluetooth.service

[Service]
ExecStart=/usr/bin/bluetooth-reconnect

[Install]
WantedBy=bluetooth.service