#!/usr/bin/env bash
###########################################################################
##  Copyright (C) Wizardry and Steamworks 2024 - License: MIT            ##
###########################################################################
# This script can be used to make a daemon reload its configuration       #
# whenever a change occurs within a defined directory, presumably the     #
# same directory where the configuration is stored in the first place.    #
#                                                                         #
# The script requires the "inotify-tools" package to be installed or      #
# whatever other package provides the "inotifywait" command line tool.    #
# Next, the script must be modified to make the necessary changes in the  #
# "CONFIGURATION" section where the path to the directory to be watched   #
# is specified and to also define a command that should be used to reload #
# the daemon. Note that whatever the command contains, must also be       #
# installed for the script to work.                                       #
#                                                                         #
# The script has to be ran permanently for the entire duration that the   #
# processes that it is monitoring is running. This can be accomplished by #
# starting the script using "supervisord" or any other tool that can run  #
# daemons, including bash scripts.                                        #  
###########################################################################

###########################################################################
#                             CONFIGURATION                               #
###########################################################################

MONITOR_DIRECTORY=/data
RELOAD_COMMAND="kill -s HUP `pidof freeradius`"

###########################################################################
#                               INTERNALS                                 #
###########################################################################

# alarm(2)
function alarm {
    sleep $1
    eval $RELOAD_COMMAND
}

ALARM_PID=0
trap '{ test $ALARM_PID = 0 || kill -9 $ALARM_PID; }' KILL QUIT TERM EXIT INT HUP

inotifywait -q -m "$MONITOR_DIRECTORY" -r \
    -e "modify" -e "create" -e "delete" | \
    while IFS=$'\n' read -r LINE; do
    if [ -d /proc/"$ALARM_PID" ]; then
        kill -9 $ALARM_PID &>/dev/null || true
    fi
    alarm "5" &
    ALARM_PID=$!
done