python怎么将打印输出日志文件

import sys

# make a copy of original stdout route

stdout_backup = sys.stdout

# define the log file that receives your log info

log_file = open("message.log", "w")

# redirect print output to log file

sys.stdout = log_file

print "Now all print info will be written to message.log"

# any command line that you will execute

...

log_file.close()

# restore the output to initial pattern

sys.stdout = stdout_backup

print "Now this will be presented on screen"