Listing 3 secs2dhms

#!/bin/ksh
# Listing 3: secs2dhms
# This script accepts a number of seconds argument and returns a string 
# in hours, minutes and seconds with corresponding labels.  For example,
# executing:
#
# secs2dhms 94550
#
# returns:
#
# 1 day 2 hours 15 minutes 50 seconds

TRUE=0
FALSE=1

integer SECONDS_IN_DAY=86400
integer SECONDS_IN_HOUR=3600
integer SECONDS_IN_MINUTE=60

readonly SECONDS_IN_DAY SECONDS_IN_HOUR SECONDS_IN_MINUTE

integer days=0
integer hours=0
integer minutes=0
integer seconds=0

need_space=$FALSE

# This function returns true if $1 is an integer. otherwise, returns false
is_integer()
{
# echo the argument to eliminate white space.
    case $(echo $1) in
        +([-+0-9])) return 0 ;;
        *) return 1 ;;
    esac
}

echo_s()
{
    if (( $1 != 1 ))
    then
        echo "s\c"
    fi
}

if [[ -z $1 ]]
then
    read operand
else
    operand=$1
fi

if is_integer $operand
then
    seconds=$operand
else
    echo "$operand is not an integer!"
    return 1
fi

if (( $seconds < 0 ))
then
    seconds=$(($seconds * -1))
    sign="-"
else
    sign=""
fi
    
if (( "$seconds" >= $SECONDS_IN_DAY ))
then
    days=$(( $seconds / $SECONDS_IN_DAY ))
    seconds=$(( $seconds % $SECONDS_IN_DAY ))
fi

if (( "$seconds" >= $SECONDS_IN_HOUR ))
then
    hours=$(( $seconds / $SECONDS_IN_HOUR ))
    seconds=$(( $seconds % $SECONDS_IN_HOUR ))
fi

if (( "$seconds" >= $SECONDS_IN_MINUTE ))
then
    minutes=$(( $seconds / $SECONDS_IN_MINUTE ))
    seconds=$(( $seconds % $SECONDS_IN_MINUTE ))
fi

[[ -n "$sign" ]] && echo "$sign\c"

if (($days > 0)) || (($hours > 0)) || (($minutes > 0)) || (($seconds > 0))
then
    if (($days > 0))
    then
        echo "$days day\c"
        echo_s $days
        need_space=$TRUE
    fi
    if (($hours > 0))
    then
        [[ $need_space -eq $TRUE ]] && echo " \c"
        echo "$hours hour\c"
        echo_s $hours
        need_space=$TRUE
    fi
    if (($minutes > 0))
    then
        [[ $need_space -eq $TRUE ]] && echo " \c"
        echo "$minutes minute\c"
        echo_s $minutes
        need_space=$TRUE
    fi
    if (($seconds > 0))
    then
        [[ $need_space -eq $TRUE ]] && echo " \c"
        echo "$seconds second\c"
        echo_s $seconds
    fi
else
    echo "0 seconds\c"
fi