iter_over_txt_file_lines.sh

#!/bin/bash

# Looping through the content of a file in Bash
# source: https://stackoverflow.com/questions/1521462/looping-through-the-content-of-a-file-in-bash

# iterating over lines of text file
#
while read line; do
  echo "$line"
done <blt_devs.txt

# iterating over stdout returning directly from an app
#
bluetoothctl devices | while read line; do echo $line; done
# or
bluetoothctl devices | while read line || [[ -n $line ]]; do echo $line; done
# or
while read line; do echo $line; done < <(bluetoothctl devices)
# what '< <' means:
# see: What's the difference between <<, <<< and < < in bash?
# https://askubuntu.com/questions/678915/whats-the-difference-between-and-in-bash