#! /bin/sh

#
# Marc Groenewegen  2004,2011
#


if [ $# -lt 1 ]; then
  echo "pictrename: create new names for a range of files"
  echo
  echo "usage: pictrename <newbasename> [start] [increment]"
  echo "arguments:"
  echo "* New base name"
  echo "* Start of numbering (defaults to 1)"
  echo "* Increment for file name numbering (defaults to 1)"
  echo
  exit
fi


newbasename=$1

# defaults
firstfile=1
filenumber=1
step=1;


if [ $# -gt 1 ]; then
  firstfile=$2
  if [ $firstfile -gt 0 ]; then
    filenumber=$firstfile
    echo "Start numbering at $firstfile"
  fi
fi


if [ $# -gt 2 ]; then
  increment=$3
  if [ $increment -gt 0 ]; then
    step=$increment
    echo "Step size: $step"
  fi
fi


for f in *.jpg; do
  numberstring=`printf %04d $filenumber`
  echo "renaming $f to ${newbasename}_${numberstring}.jpg"
  mv $f ${newbasename}_${numberstring}.jpg
  #(( filenumber = filenumber + 1 ))  UNSAFE !!
  filenumber=`expr $filenumber + $step`
done

