Re: unix tool as precise counter/timer for periodic print/exec

[Johannes Schauer <j.schauer@email.de>]

Hi Karl,

> Perhaps the sleepenh package will help you?
> 
> Not a solution per se, but possibly a useful building block..

It works perfectly and was exactly what I was looking for! Thanks a lot!

In case anybody ever finds this thread later on, this is what I now
wrote based on sleepenh which does exactly what I was looking for in my
initial email:

--%<---------------------------------------------------------------------------
#!/bin/sh

usage() {
  echo "Usage: $0 [ARGS] [COMMAND]"
  echo
  echo "It counts upward (default) or downward (-d) starting at START (-s)"
  echo "with a configurable floating point interval of SECS seconds (-n,"
  echo "default 1.0) until infinity (default) or up to a maximum number of"
  echo "COUNT intervals (-c). It optionally prints this counter (-p) and/or"
  echo "the current date (-t) at each interval. It optionally executes a"
  echo "COMMAND per interval which it can also fork (-f) in case the command"
  echo "is expected to take longer than SECS seconds."
  echo
  echo "  -f       fork COMMAND"
  echo "  -p       print counter"
  echo "  -d       count downward (default: upward)"
  echo "  -n SECS  interval of SECS (can be floating point)"
  echo "  -c COUNT only run for COUNT interval(s)"
  echo "  -s START start counting at START"
  echo "  -t       print the output of date(1) every interval"
  echo "  -h       print this help message"
}

INTERVAL=1.0
MAX_COUNT=-1
DOWN=0
PRINT=0
FORK=0
PRINT_DATE=0
START=0

while getopts fpdn:c:s:th option; do
  case $option in
    f)
      FORK=1
      ;;
    p)
      PRINT=1
      ;;
    d)
      DOWN=1
      ;;
    n)
      INTERVAL="$OPTARG"
      ;;
    c)
      MAX_COUNT="$OPTARG"
      ;;
    s)
      START="$OPTARG"
      ;;
    t)
      PRINT_DATE=1
      ;;
    h)
      usage
      exit 0
      ;;
    [?])
      usage 1>&2
      exit 1
      ;;
  esac
done
shift $(($OPTIND - 1))

TIMESTAMP=`sleepenh 0`

I=$START
while true; do
  if [ $# -ne 0 ]; then
    if [ $FORK -eq 1 ]; then
      $@ &
    else
      $@
    fi
  fi
  if [ $PRINT -eq 1 ]; then
    echo $I
    if [ $DOWN -eq 0 ]; then
      I=$((I+1))
    else
      I=$((I-1))
    fi
  fi
  if [ $PRINT_DATE -eq 1 ]; then
    date
  fi
  if [ $DOWN -eq 0 ]; then
    [ $((I-START)) -gt $MAX_COUNT ] && break
  else
    [ $((START-I)) -gt $MAX_COUNT ] && break
  fi
  TIMESTAMP=`sleepenh $TIMESTAMP $INTERVAL`; done

--%<---------------------------------------------------------------------------

Feel free to use the above in any way you want.

cheers, josch