import os
import sys
 
path = "/home/bnrc/formatm/train"

count = 0

for (path,dirs,files) in os.walk(path):
    for filename in files:
        count += 1
        first_name = filename.strip().split(‘.jpg‘)[0]
        new_name = first_name + ‘_boxes.mat‘
        print new_name
        os.rename(path+"/"+filename,path+"/"+new_name)
print count