In Bash scripting when you want to print useful information when debugging a script from terminal but not when executed in background (like from crontab)

print_debug_information.sh

#!/bin/bash

if [ -t 1 ]
then
    : # running from terminal
    debug="1"
else
    : # not running from terminal, cron maybe
    debug="0"
fi

if [ "$debug" -eq "1" ]; then
  echo "Printing my debug information"
fi
# blablabla useful code