#!/bin/sh

# Add a numeric prefix starting at $1, incrementing by $2 on $3..$n files

# (c) 2005 Jérôme SAUTRET <jerome@sautret.org>
# This script is distributed under GNU GPL. Ask Stallman for details.

# $Id: add_num_prefix,v 1.1 2005/08/22 19:58:27 jerome Exp $

set -o errexit
if [ -z "$3" ] ; then
	cat <<EoF
Usage:
`basename $0` start step files...
Add a numeric prefix starting at 'start', incrementing by 'step' on 'files'.
EoF
	exit 1
fi

set -o nounset
min=$1
len=`echo $1|wc -c|sed 's/^ *//'`
let len=len-1
min=`echo $min|sed 's/^0*//'`
inc=$2
shift 2
files="$@"

i=$min
for file in $files
do
    new=`printf "%.${len}d" $i `"_$file"
    echo "$file -> $new"
    mv "$file" "$new"
    let i=i+inc
done