How to use python remove the '^M' when copy words from Windows to Linux

今天帮同事用Python写了一个小工具，实现了在linux下批量文件名和去掉windows 文件到linux过程中产生^M的脚本，代码如下：

!/opt/exptools/bin/python
import os,os.path,sys
import shutil,string
dir ='/home/alzhong/tools/zch/filedir'


for i in os.listdir(dir):


    newfile = i.replace('.s.txt','.s')


    oldfullfile = dir+"/"+i
    newfullfile = dir+'/'+newfile
        #corrform_cmd="winrar a '%s' %s" % (target, source)
    try:
        corrform_cmd="cat %s | tr -d "
" > %s"%(oldfullfile, newfullfile)
        os.system(corrform_cmd)
        print "%s transform to %s successfully!"%(i, newfile)
    except:
        print "%s transform to %s failed!"%(i, newfile)
    try:
        rm_cmd="rm -rf %s"%(oldfullfile)
        os.system(rm_cmd)
        print "%s removed successfully!"%(i)
    except:
        print "%s removed failed!"%(i)
    #shutil.move(oldfullfile,newfullfile)