#!/bin/sh

# ren.sh
# Use this script to rename a group of .jpg files to new names sequentially.
#
# Parameters
#   - New file name prefix.  For example, to rename a group of files 
#     Vacation1.jpg, Vacation2.jpg, etc, pass the first parm as Vacation
#   - Files to rename (Up to 9 I think)

if [ $# -lt 2 ] ; then
  echo "Usage: ren.sh FilePrefix File1.jpg File2.jpg ..."
  exit
fi

# Set initial number to 0
num=0

# Loop through all parameters passed to script
for i in $*
do
  # First parameter is the prefix.
  if [ $num -eq 0 ] ; then
    prefix_name=$i;
  else
    # Remaining parameters are the original file names

    # Check if the new file name already exists.  Keep incrementing the
    # counter until we find a name that is not already in use.
    exists="Y"

    while [ $exists = "Y" ] 
    do
      if [ $num -lt 10 ] ; then
        new_file=$prefix_name"0"$num.jpg
      else
        new_file=$prefix_name$num.jpg 
      fi

      if [ -f $new_file ] ; then
        num=`expr $num + 1`
      else
        exists="N"
      fi
    done

    # Rename the file
    mv $i $new_file
  fi
 
  num=`expr $num + 1`
done