A Little bash script that can notify whenever a site you own goes down.

Of course there are more sofisticated ways to achieve better results but this script is simple enough to be set up in a minute. You can pass a file containing all the sites to check with the -f flag, this is useful when used in a crontab for instance, instead if you want to rapidly do a loop on the command line you can pass a single site with the -s flag.

home='/path/to/homefolder'
targetfile="$home/Desktop/SITES_NOT_RESPONDING"
 
function checksite(){
    HEAD "$1" > "$home/output"
    grep "^4[0-9][0-9]" < "$home/output" >> "$home/errors"
    grep "^5[0-9][0-9]" < "$home/output" >> "$home/errors"
 
    if [ -s errors ]; then
        /usr/bin/beep -f 1800 -l 200 -r 4 -d 500
        echo "$1" >> "$targetfile"
        cat "$home/errors" >> "$targetfile"
        echo '' >> "$targetfile"
    	notify-send -t 5000 "$1 is down!" 
        rm "$home/output" "$home/errors"
    fi
}
 
function loopfile(){
    while read line
        do
            checksite "$line"
        done < "$1"
}
 
while getopts s:f: options
    do
        case $options in
            f) loopfile $OPTARG;;
            s) checksite $OPTARG;;
        esac
    done

Get the source code here.