python将print输出结果写入文件

python -u test.py > a.log
# 将打印的结果输出到log -u是清空变量

# assume the log file is 'a.log'
# for python2
print >> a.log, 'print something'
# for python3
print('print something', file=a.log)

import sys
f = open('a.log', 'a')
sys.stdout = f
sys.stderr = f        # redirect std err, if necessary

import sys
class Logger(object):
    def __init__(self, filename='default.log', stream=sys.stdout):
        self.terminal = stream
        self.log = open(filename, 'a')

    def write(self, message):
        self.terminal.write(message)
        self.log.write(message)

    def flush(self):
        pass

sys.stdout = Logger(a.log, sys.stdout)
sys.stderr = Logger(a.log_file, sys.stderr)        # redirect std err, if necessary

# now it works
print 'print something'