This script lets you define rules to rename your files in a specific directory.

replace_filename.py

#!/usr/bin/env python
# -*- coding: iso-8859-1 -*-
__version__ = "$Revision: 0.2$"
__author__ = "Pierrick Terrettaz"
__date__ = "2006-12-09"

import os, sys, re
from optparse import OptionParser

def rename_file(path, search, replace, options, sub):
    f = os.path.basename(path)
    d = os.path.dirname(path)
    new_name = sub(f, search, replace)
    if new_name != None:
        new_path = os.path.join(d, new_name)
        if options.verbose or options.simulation:
            print '%(path)s -> %(new_path)s' % locals()
        if not options.simulation:
            os.rename(path, new_path)
        return 1
    return 0

def rename_in_dir(d, search, replace, options, sub):
    count = 0
    total = 0
    for f in os.listdir(d):
        path = os.path.join(d, f)
        if options.recursive and os.path.isdir(path):
            c, t = rename_in_dir(path, search, replace, options, sub)
            count += c
            total += t
        
        if options.directories_only and os.path.isfile(path):
            continue
        
        if options.files_only and os.path.isdir(path):
            continue
        
        count += rename_file(path, search, replace, options, sub)
        total += 1
    return count, total

def std_sub(string, search, replace):
    if string.find(search) != -1:
        return string.replace(search, replace)
    return None

def re_sub(string, search, replace):
    new_name = re.sub(search, replace, string)
    if new_name != string:
        return new_name
    return None

if __name__ == "__main__":
    parser = OptionParser()
    parser.set_usage("%s directory search_string replace_string" % os.path.basename(sys.argv[0]))
    parser.add_option("-r", "--recursive", action="store_true", dest="recursive", default=False, help="recursive mode")
    parser.add_option("-v", "--verbose", action="store_true", dest="verbose", default=False, help="verbose output")
    parser.add_option("-f", "--file-only", action="store_true", dest="files_only", default=False, help="process only on files")
    parser.add_option("-d", "--directory-only", action="store_true", dest="directories_only", default=False, help="process only on directories")
    parser.add_option("-s", "--simulate", action="store_true", dest="simulation", default=False, help="make a simulation of the renaming")
    parser.add_option("-e", "--use-regex", action="store_true", dest="regex", default=False, help="use input as regex. if regex contains groups, use \\1")
    (options, args) = parser.parse_args()

    if len(args) != 3:
        parser.print_usage()
        sys.exit(1)

    (path, search, replace) = args

    if path == "/":
        print "WARNING: Do you really want to rename all files of root directory ? [y/n]"
        if sys.stdin.readline() != "y\n":
            sys.exit(0)
    
    if options.regex:
        sub =  re_sub
    else:
        sub = std_sub
    
    count, total = rename_in_dir(path, search, replace, options, sub)
    print "%(total)d entries scanned, %(count)d entries renamed" % locals()