Prints the triforce

triforce.sh

#!/usr/bin/env bash
#
#   Triforce
#   By: Aaron
#   Date: July 30, 2012
#
#   This script will only accept one argument that should be a number greater than or equal to 11.
#   It will print a triforce symbol with the base being as wide as the nearest odd number to the one provided.
#
#   Screenshot: http://newroman.net/permalink/triforce.png
#

if [ $# != 1 ] || [ $1 -lt 11 ]
then
    printf "This script can only accept one argument. That should be a number that is greater than or equal to 11\n"
    exit 1
fi

if [ `expr $1 % 2` -eq 0 ]
then
    base=`expr $1 - 1`
else
    base=$1
fi

check=`expr $base - 1`
check=`expr $base / 2`
if [ `expr $check % 2` -eq 0 ]
then
    base=`expr $base + 2`
fi

ospaces=`expr $(($base - 1)) / 2`
tbase=$ospaces
stars=-1

counter=0
tlimit=`expr $(($tbase + 1)) / 2`
while [ $counter -lt $tlimit ]
do
    spacecounter=0
    while [ $spacecounter -lt $ospaces ]
    do
        printf " "
        spacecounter=`expr $spacecounter + 1`
    done

    starcounter=0
    stars=`expr $stars + 2`
    while [ $starcounter -lt $stars ]
    do
        printf "*"
        starcounter=`expr $starcounter + 1`
    done

    printf "\n"
    counter=`expr $counter + 1`
    ospaces=`expr $ospaces - 1`
    ispaces=$stars
done

stars=-1
while [ $ospaces -ge 0 ] && [ $ispaces -ge 1 ]
do
    spacecounter=0
    while [ $spacecounter -lt $ospaces ]
    do
        printf " "
        spacecounter=`expr $spacecounter + 1`
    done
    ospaces=`expr $ospaces - 1`

    stars=`expr $stars + 2`
    starcounter=0
    while [ $starcounter -lt $stars ]
    do
        printf "*"
        starcounter=`expr $starcounter + 1`
    done

    spacecounter=0
    while [ $spacecounter -lt $ispaces ]
    do
        printf " "
        spacecounter=`expr $spacecounter + 1`
    done
    ispaces=`expr $ispaces - 2`

    starcounter=0
    while [ $starcounter -lt $stars ]
    do
        printf "*"
        starcounter=`expr $starcounter + 1`
    done

    printf "\n"
done