Get uptime and second conversion

up.sh

#!/bin/bash -

PROGRAM="${0##*/}"

IFS="."
for i in $(cat /proc/uptime)
do
  UPTIME=$i
  break
done

SECONDS_IN_DAY=86400
SECONDS_IN_HOUR=3600
MINUTES_IN_HOUR=60
SECONDS_IN_MINUTE=60

VERBOSE=0

HELP="\
$PROGRAM - report uptime and second conversion
Usage: $PROGRAM [-h] [-v] [-s sec]
  -h      show this help and exit
  -v      show verbose output
  -s sec  convert seconds to formatted time\
"

while [ $# -gt 0 ]
do
  case $1 in
    -h|--h*)
         echo "$HELP"
         exit
         ;;
    -v|--v*)
         shift
         VERBOSE=1
         ;;
    -s|--s*)
         shift
         if [ "$1" ]; then
           case $1 in
           *[!0-9]*)
             echo "invalid argument - $1"
             echo "$HELP"
             exit 1
             ;;
           *)
             UPTIME=$1
             shift
             ;;
           esac
         else
           echo "-s flag requires an argument."
           echo "$HELP"
           exit 1
         fi
         ;;
    *)
         echo "invalid flag - $1"
         echo "$HELP"
         exit 1
         ;;
  esac
done

case $VERBOSE in
  0)
    days=$(( UPTIME / SECONDS_IN_DAY ))
    SECONDS=$(( UPTIME % SECONDS_IN_DAY ))
    printf "%02d:%02d:%02d:%02d\n" "$days" "$((SECONDS / SECONDS_IN_HOUR))" \
    "$(((SECONDS / MINUTES_IN_HOUR) % MINUTES_IN_HOUR))" "$((SECONDS % SECONDS_IN_MINUTE))"
    ;;
  1)
    days=$(( UPTIME / SECONDS_IN_DAY ))
    SECONDS=$(( UPTIME % SECONDS_IN_DAY ))
    printf "$days days, $((SECONDS / SECONDS_IN_HOUR)) hours, "
    printf "$(((SECONDS / MINUTES_IN_HOUR) % MINUTES_IN_HOUR)) minutes, "
    printf "$((SECONDS % SECONDS_IN_MINUTE)) seconds\n"
    ;;
esac