Mine

# Perform a certain action on specified time (useful as an alarm clock).function alarm {  usage="usage: $(basename $0) HH[:MM[:SS]] [action]"  default_action="mpc play"  if [[ $# -lt 1 ]]; then    print -- $usage    return 1  fi  wtime=$1  shift  action="$default_action"  if [[ $# -gt 0 ]]; then    action="$@"  fi  wsplit=(${(s.:.)wtime})  integer H=${wsplit[1]} M=${wsplit[2]:-0} S=${wsplit[3]:-0}  if [[ $#wsplit > 3 || $H -ge 24 || $M -ge 60 || $S -ge 60 ]]; then     print -- $usage    return 1  fi  dtime=$(date +%T)  ds=(${(s.:.)dtime})  integer CH=${ds[1]} CM=${ds[2]} CS=${ds[3]}  (( sleeptime = ($H - $CH) * 3600 + ($M - $CM) * 60 + $S - $CS ))  if (( $sleeptime < 0 )); then (( sleeptime = (24*3600) + $sleeptime )); fi  sleep $sleeptime  print -- "[$(red alarm) $(green $wtime)]: $action"  if eval $action; then    return 0  fi  return 1}