gistfile1.txt

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

        then
         ls | sort | run-parts ${BASH_SOURCE[0]}
fi

if [ $1 ! 1 ]

        then

        echo "Invalid number of arguments"

        exit

fi

if [ ! -d $1 ]

        then

        echo "directory does not exist"

        exit
fi
        cd $1
        ls $1 | sort | xargs run-parts