Output of python log (Logger)

method one:

import sys

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

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

    def flush(self):
        pass


# now it works
sys.stdout = Logger('a.txt', sys.stdout)

print('print something')

import time
for i in range(10):
    now = time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(time.time()))  # get time
    print("now-->", now)  # 将会输出到控制台，且同时输出到日志文件中去 
    time.sleep(1)  # 间隔1秒输出

illustrate:

• When the content of a print() line is extremely long (for example: very long JSON format text), the content of the file will not be displayed completely, there is a length limit, and it will automatically disappear at a certain point. That is to say: when using this method, there is a length limit for single-line text.
  Specific reference: Safe Development/Python–29–Console content is output to a local file

Method Two:

mylog = open('a.txt', mode='a', encoding='utf-8')  # 设置输出的文件及设置

print("now we will start!!!")  # 输出到控制台
print("now we will start!!!", file=mylog)  # 输出到日志文件中去

import time
for i in range(10):
    now = time.strftime('%Y%m%d_%H%M%S', time.localtime(time.time()))
    print("now --> {} \n".format(now), file=mylog)
    time.sleep(1)
    print(time.time())

mylog.close()  # 关闭日志流

Or write like this (all are only output to the log file)

sys.stdout = open('a.txt', mode='a', encoding='utf-8')  # 设置输出的文件及设置

print("now we will start!!!")  # 输出到日志文件中去

import time
for i in range(10):
    now = time.strftime('%Y%m%d_%H%M%S', time.localtime(time.time()))
    print("now --> {} \n".format(now))
    time.sleep(1)
    print(time.time())

Method 3:

Execute in the terminal, such as:python your_program.py > logger.txt