gistfile1.txt

#!/bin/bash
if [ "$#" -eq 0 ]

        then
        cd "$(dirname ${BASH_SOURCE[0]})"
         ls | sort | run-parts
fi

if [ $1 ! 1 ]

        then

        echo Invalid number of arguments

        exit

fi

if [ ! -d $1 ]

        then

        echo directory does not exist

        exit
fi

        ls $1 | sort | run-parts $1