rn.sh

# swap names of 2 files
if [ $# -eq 2 ]
then
    mv $1 $1.backup
    mv $2 $1
    mv $1.backup $2
fi

# swap %file_name% with %file_name%.backup
if [ $# -eq 1 ] && [ -f $1.backup ] || [ -d $1.backup ];
then
    mv $1 $1._backup
    mv $1.backup $1
    mv $1._backup $1.backup
fi