#!/bin/sh
# vim: set sw=4 ts=4 et: 
# written by guido socher
ver="0.1"
help()
{
    cat <<HELP
rotatefile -- rotate the file name 

USAGE: rotatefile [-h]  filename

OPTIONS: -h this help

EXAMPLE: rotatefile sdat.txt
This will e.g rename  ... sdat.txt.1 to sdat.txt.2, sdat.txt.0 to sdat.txt.1 and sdat.txt to sdat.txt.0
and create an empty sdat.txt file

The max number is 20

version $ver
HELP
    exit 0
}

error()
{
    echo "$1"
    exit "$2"
}
while [ -n "$1" ]; do
case $1 in
    -h) help;shift 1;;
    --) break;;
    -*) echo "error: no such option $1. -h for help";exit 1;;
    *)  break;;
esac
done

# input check:
[ -z "$1" ] && error "ERROR: you must specify a file, use -h for help" 1
filen="$1"
for n in 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0; do
    if [ -f "$filen.$n" ]; then
        p=`expr $n + 1`
	    echo "OK rotatefile: mv $filen.$n $filen.$p"
	    mv $filen.$n $filen.$p
    fi
done
if [ -f "$filen" ]; then
    echo "OK rotatefile: cp $filen $filen.0"
    cp -p $filen $filen.0
fi
echo "OK rotatefile: cp /dev/null $filen"
cp /dev/null $filen