#!/usr/bin/bash
# Note, "[[ ]]" and "if [] && []" is bash/ksh88 ONLY

if [ -z ${1} ]; then tweetnum=1
elif [[ ${1} =~ ^[0-9]+$ ]] ; then
        if [ ${1} -gt 0 ] && [ ${1} -lt 11 ]; then tweetnum=$1
        else echo "Number outside of range 1..10"; exit 0;
        fi
else echo "That's not a number. Please use a number in the range 1..10"; exit 0;
fi

echo "Tweet # ${tweetnum}"