watcher.sh runs a comand at an internal and speaks when the status changes.

watcher.sh

#!/bin/bash

# TODO:
# This was a 5 minute hack.
# Currently assumes presence of `say` command (macOS). Make more OS tolerant. Possibly changing *_MSG to *_CMD

usage(){
    cat<<USAGE
$0 runs a comand at an internal and speaks when the status changes.
Accepts optional ENV vars: SUCCESS_MSG and FAILURE_MSG

Usage:
$0 <interval_seconds> <command>

Example:
SUCCESS_MSG="Internet online" FAILURE_MSG="Internet offline" watcher.sh 4 dig google.com +time=1

USAGE
}

if [[ $# -lt 2 ]]; then
    usage
    exit 255
fi

success_message="${SUCCESS_MSG:-Command was successful}"
failure_message="${FAILURE_MSG:-Command failed}"
default_message=""

delay=$1
shift
cmd="$@"

tmp1=$(mktemp /tmp/$(basename $0).curr.XXXXX)
tmp2=${tmp1/curr/prev}; touch $tmp2

run_cmd(){
    $cmd
    status=$?
    cp $tmp1 $tmp2
    if $(exit $status); then
        echo $success_message > $tmp1
    else
        echo $failure_message > $tmp1
    fi
    if ! diff $tmp1 $tmp2 > /dev/null; then 
        say "$(cat $tmp1)"
    fi
}

run_conditional(){
    true
}

main(){
    echo $default_message | tee $tmp1 > $tmp2
    while run_conditional; do
        run_cmd
        sleep $delay
    done
}

main "$@"