常用模块学习（六）

                                 常用模块学习（六）

• 常用模块学习—subprocess模块详解2

  • subprocess.call()方法

    #执行命令，返回命令执行状态 ， 0 or 非0
    >>> retcode = subprocess.call(["ls", "-l"])
    
    #执行命令，如果命令结果为0，就正常返回，否则抛异常
    >>> subprocess.check_call(["ls", "-l"])
    0
    
    #接收字符串格式命令，返回元组形式，第1个元素是执行状态，第2个是命令结果 
    >>> subprocess.getstatusoutput('ls /bin/ls')
    (0, '/bin/ls')
    
    #接收字符串格式命令，并返回结果
    >>> subprocess.getoutput('ls /bin/ls')
    '/bin/ls'
    
    #执行命令，并返回结果，注意是返回结果，不是打印，下例结果返回给res
    >>> res=subprocess.check_output(['ls','-l'])
    >>> res
    b'total 0
    drwxr-xr-x 12 alex staff 408 Nov 2 11:05 OldBoyCRM
    '

    [root@wuqianqian-learn ~]# python3
    
    >>> import os
    >>> os.system('uname -a ')
    Linux wuqianqian-learn 2.6.32-696.el6.x86_64 #1 SMP Tue Mar 21 19:26:13 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
    >>> import subprocess              
    >>> subprocess.call(['ls','-lsh'])
    total 0
    >>> subprocess.check_call(['ls','-lsh'])
    total 0
    >>> subprocess.check_call(['ls','-lsh'])
    total 80K
    srwxr-xr-x 1 root root    0 May 30 10:25 Aegis-<Guid(5A2C30A2-A87D-490A-9281-6765EDAD7CBA)>
    4.0K drwx------ 3 root root 4.0K May 26 11:18 systemd-private-d3b6074cca274d6593128b80ade5cf96-ntpd.service-FZcU6R
    >>> subprocess.getoutput(['ls','-lsh']) 
    'Aegis-<Guid(5A2C30A2-A87D-490A-9281-6765EDAD7CBA)>
    systemd-private-d3b6074cca274d6593128b80ade5cf96-ntpd.service-FZcU6R'
    >>> subprocess.getoutput(['ls /bin/ls'])
    '/bin/ls'
    >>> res = subprocess.checkoutput(['ls','-l'])       
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    AttributeError: module 'subprocess' has no attribute 'checkoutput'
    >>> res = subprocess.check_output(['ls','-l'])
    >>> res
    b'total 4
    srwxr-xr-x 1 root root    0 May 30 10:25 Aegis-<Guid(5A2C30A2-A87D-490A-9281-6765EDAD7CBA)>
    drwx------ 3 root root 4096 May 26 11:18 systemd-private-d3b6074cca274d6593128b80ade5cf96-ntpd.service-FZcU6R
    '
    >>> help(subprocess.check_output)
    Help on function check_output in module subprocess:
    
    check_output(*popenargs, timeout=None, **kwargs)
        Run command with arguments and return its output.
        
        If the exit code was non-zero it raises a CalledProcessError.  The
        CalledProcessError object will have the return code in the returncode
        attribute and output in the output attribute.
        
        The arguments are the same as for the Popen constructor.  Example:
        
        >>> check_output(["ls", "-l", "/dev/null"])
        b'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null
    '
        
        The stdout argument is not allowed as it is used internally.
        To capture standard error in the result, use stderr=STDOUT.
        
        >>> check_output(["/bin/sh", "-c",
        ...               "ls -l non_existent_file ; exit 0"],
        ...              stderr=STDOUT)
        b'ls: non_existent_file: No such file or directory
    '
        
        There is an additional optional argument, "input", allowing you to
        pass a string to the subprocess's stdin.  If you use this argument
        you may not also use the Popen constructor's "stdin" argument, as
        it too will be used internally.  Example:
        
        >>> check_output(["sed", "-e", "s/foo/bar/"],
        ...              input=b"when in the course of fooman events
    ")
        b'when in the course of barman events
    '
        
        If universal_newlines=True is passed, the "input" argument must be a
        string and the return value will be a string rather than bytes.

  • subprocess.Popen()方法

                  常用参数：

• • • args：shell命令，可以是字符串或者序列类型（如：list，元组）

    • stdin, stdout, stderr：分别表示程序的标准输入、输出、错误句柄

    • preexec_fn：只在Unix平台下有效，用于指定一个可执行对象（callable object），它将在子进程运行之前被调用

    • shell：同上

    • cwd：用于设置子进程的当前目录

    • env：用于指定子进程的环境变量。如果env = None，子进程的环境变量将从父进程中继承。

  • 下面这2条语句执行会有什么区别？

    a=subprocess.run('sleep 10',shell=True,stdout=subprocess.PIPE)
    a=subprocess.Popen('sleep 10',shell=True,stdout=subprocess.PIPE)

    区别是Popen会在发起命令后立刻返回，而不等命令执行结果。这样的好处是什么呢？

    如果你调用的命令或脚本 需要执行10分钟，你的主程序不需卡在这里等10分钟，可以继续往下走，干别的事情，每过一会，通过一个什么方法来检测一下命令是否执行完成就好了。

    Popen调用后会返回一个对象，可以通过这个对象拿到命令执行结果或状态等，该对象有以下方法

    poll()

    Check if child process has terminated. Returns returncode

    wait()

    Wait for child process to terminate. Returns returncode attribute.

    terminate()终止所启动的进程Terminate the process with SIGTERM

    kill() 杀死所启动的进程 Kill the process with SIGKILL

    communicate()与启动的进程交互，发送数据到stdin,并从stdout接收输出，然后等待任务结束

    >>> a = subprocess.Popen('python3 guess_age.py',stdout=subprocess.PIPE,stderr=subprocess.PIPE,stdin=subprocess.PIPE,shell=True)
    
    >>> a.communicate(b'22')
    
    (b'your guess:try bigger
    ', b'')       

      send_signal(signal.xxx)发送系统信号

      pid 拿到所启动进程的进程号

[root@wuqianqian-learn ~]# python3

>>> import os
>>> os.system('uname -a ')
Linux wuqianqian-learn 2.6.32-696.el6.x86_64 #1 SMP Tue Mar 21 19:26:13 UTC 2017 x86_64 x86_64 x86_6
>>> import subprocess              
>>> subprocess.call(['ls','-lsh'])
total 0
>>> subprocess.check_call(['ls','-lsh'])
total 0
>>> subprocess.check_call(['ls','-lsh'])
total 4.0K
srwxr-xr-x 1 root root    0 May 30 10:25 Aegis-<Guid(5A2C30A2-A87D-490A-9281-6765EDAD7CBA)>
4.0K drwx------ 3 root root 4.0K May 26 11:18 systemd-private-d3b6074cca274d6593128b80ade5cf96-ntpd.service-FZcU6R
>>> subprocess.getoutput(['ls','-lsh']) 
'Aegis-<Guid(5A2C30A2-A87D-490A-9281-6765EDAD7CBA)>
systemd-private-d3b6074cca274d6593128b80ade5cf96-ntpd.service-FZcU6R'
>>> subprocess.getoutput(['ls /bin/ls'])
'/bin/ls'
>>> res = subprocess.checkoutput(['ls','-l'])       
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: module 'subprocess' has no attribute 'checkoutput'
>>> res = subprocess.check_output(['ls','-l'])
>>> res
b'total 4
srwxr-xr-x 1 root root    0 May 30 10:25 Aegis-<Guid(5A2C30A2-A87D-490A-9281-6765EDAD7CBA)>
drwx------ 3 root root 4096 May 26 11:18 systemd-private-d3b6074cca274d6593128b80ade5cf96-ntpd.service-FZcU6R
'
>>> help(subprocess.check_output)
Help on function check_output in module subprocess:

check_output(*popenargs, timeout=None, **kwargs)
    Run command with arguments and return its output.
    
    If the exit code was non-zero it raises a CalledProcessError.  The
    CalledProcessError object will have the return code in the returncode
    attribute and output in the output attribute.
    
    The arguments are the same as for the Popen constructor.  Example:
    
    >>> check_output(["ls", "-l", "/dev/null"])
    b'crw-rw-rw- 1 root root 1, 3 Oct 18  2007 /dev/null
'
    
    The stdout argument is not allowed as it is used internally.
    To capture standard error in the result, use stderr=STDOUT.
    
    >>> check_output(["/bin/sh", "-c",
    ...               "ls -l non_existent_file ; exit 0"],
    ...              stderr=STDOUT)
    b'ls: non_existent_file: No such file or directory
'
    
    There is an additional optional argument, "input", allowing you to
    pass a string to the subprocess's stdin.  If you use this argument
    you may not also use the Popen constructor's "stdin" argument, as
    it too will be used internally.  Example:
    
    >>> check_output(["sed", "-e", "s/foo/bar/"],
    ...              input=b"when in the course of fooman events
")
    b'when in the course of barman events
'
    
    If universal_newlines=True is passed, the "input" argument must be a
    string and the return value will be a string rather than bytes.

>>> 
>>> a = subprocess.run('sleep 10',shell=True,stdout=subprocess.PIPE)
>>> subprocess.Popen()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: __init__() missing 1 required positional argument: 'args'
>>> a = subprocess.Popen('sleep 10',shell=True,stdout=subprocess.PIPE)   
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a = subprocess.Popen('sleep 10',shell=True,stdout=subprocess.PIPE)
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> a.poll()
>>> def sayhi():
... print('run...hahahah')
  File "<stdin>", line 2
    print('run...hahahah')
        ^
IndentationError: expected an indented block
>>> def sayhi():          
...     print('run...hahahah')
... a = subprocess.Popen('sleep 10',shell=True,stdout=subprocess.PIPE,preexec_fn=sayhi)
  File "<stdin>", line 3
    a = subprocess.Popen('sleep 10',shell=True,stdout=subprocess.PIPE,preexec_fn=sayhi)
    ^
SyntaxError: invalid syntax
>>> a = subprocess.Popen('sleep 10',shell=True,stdout=subprocess.PIPE,preexec_fn=sayhi)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
NameError: name 'sayhi' is not defined
>>> def sayhi():              
...     print('run...hahahah')
... a = subprocess.Popen('sleep 10',shell=True,stdout=subprocess.PIPE,preexec_fn=sayhi)
  File "<stdin>", line 3
    a = subprocess.Popen('sleep 10',shell=True,stdout=subprocess.PIPE,preexec_fn=sayhi)
    ^
SyntaxError: invalid syntax
>>> import subprocess
>>> def sayhi():              
...     print('run...hahahah')
... 
>>> 
>>> a = subprocess.Popen('sleep 10',shell=True,stdout=subprocess.PIPE,preexec_fn=sayhi)
>>> a.stdout
<_io.BufferedReader name=3>
>>> a.stdout.read()
b'run...hahahah
'
>>> a = subprocess.Popen('echo $PWD;sleep 4',shell=True,cwd="/tmp",stdout=subprocess.PIPE,preexec_fn=sayhi)  
>>> a.stdout.read()
b'run...hahahah
/tmp
'
>>> a = subprocess.Popen('echo $PWD;sleep 4',shell=True,stdout=subprocess.PIPE,preexec_fn=sayhi)           
>>> a.stdout.read()
b'run...hahahah
/root
'
>>> a = subprocess.Popen('echo $PWD;sleep 4',shell=True,stdout=subprocess.PIPE,preexec_fn=sayhi)
>>> a.wait()
>>> a = subprocess.Popen('echo $PWD;sleep 10',shell=True,stdout=subprocess.PIPE,preexec_fn=sayhi)
>>> a.wait()
>>> a = subprocess.Popen('sleep 100',shell=True,stdout=subprocess.PIPE)                          
>>> a.pid
>>> a.terminate()
>>> a.pid
>>> a.pid
>>> a.pid
>>> a.terminate()
>>> a = subprocess.Popen('sleep 100',shell=True,stdout=subprocess.PIPE)
>>> a.pid
>>> a.kill()
>>> a.pid   
>>> a = subprocess.Popen('for i in $(seq 1 100);do sleep 1;echo $i >>sleep.log;done',shell=True,stdout=subprocess.PIPE)
>>> a = subprocess.Popen('for i in $(seq 1 100);do sleep 1;echo $i >>sleep.log;done',shell=True,stdout=subprocess.PIPE)
KeyboardInterrupt
>>> a.pid
>>> a.kill()
KeyboardInterrupt
>>> help(os.kill)
Help on built-in function kill in module posix:

kill(pid, signal, /)
    Kill a process with a signal.

• 常用模块学习—logging模块基础

         很多程序都有记录日志的需求，并且日志中包含的信息即有正常的程序访问日志，还可能有错误、警告等信息输出，python的logging模块提供了标准的日志接口，你可以通过它存储各种格式的日志，logging的日志可以分为 debug(), info(), warning(), error() and critical()5个级别。

日志级别：

Level	When it’s used
DEBUG	Detailed information, typically of interest only when diagnosing problems. （详细信息，通常只有在诊断问题时才会感兴趣。）
INFO	Confirmation that things are working as expected. （确认一切都按预期工作。）
WARNING	An indication that something unexpected happened, or indicative of some problem in the near future (e.g. ‘disk space low’). The software is still working as expected. （这表明发生了一些意想不到的事情，或者预示着在不久的将来会出现一些问题（例如，“磁盘空间低”）。该软件仍按预期运行。）
ERROR	Due to a more serious problem, the software has not been able to perform some function. （由于一个更严重的问题，该软件无法执行某些功能。）
CRITICAL	A serious error, indicating that the program itself may be unable to continue running. （一个严重的错误，表明程序本身可能无法继续运行。）

#最简单的用法：

import logging

logging.warning("user [alex] attempted wrong password more than 3 times")
logging.critical("server is down")

 

#把日志写到文件里

import logging

logging.basicConfig(filename='log_test.log',level=logging.INFO)

#输入三条错误
logging.debug('This message should go to the log file')
logging.info('So should this')
logging.warning('And this,too')

其中下面这句中的level=loggin.INFO意思是，把日志纪录级别设置为INFO，也就是说，只有比日志是INFO或比INFO级别更高的日志才会被纪录到文件里，在这个例子， 第一条日志是不会被纪录的，如果希望纪录debug的日志，那把日志级别改成DEBUG就行了。

logging.basicConfig(filename='log_test.log',level=logging.DEBUG)

自定义日志格式

import logging

logging.basicConfig(filename='log_test.log',
                    level=logging.DEBUG,
                    format='%(asctime)s %(message)s',
                    datefmt='%m/%d/%Y %I:%M:%S %p')

logging.debug('This message should go to the log file')
logging.info('So should this')
logging.warning('And this,too')

支持的格式：

%(name)s	Logger的名字
%(levelno)s	数字形式的日志级别
%(levelname)s	文本形式的日志级别
%(pathname)s	调用日志输出函数的模块的完整路径名，可能没有
%(filename)s	调用日志输出函数的模块的文件名
%(module)s	调用日志输出函数的模块名
%(funcName)s	调用日志输出函数的函数名
%(lineno)d	调用日志输出函数的语句所在的代码行
%(created)f	当前时间，用UNIX标准的表示时间的浮 点数表示
%(relativeCreated)d	输出日志信息时的，自Logger创建以 来的毫秒数
%(asctime)s	字符串形式的当前时间。默认格式是 “2003-07-08 16:49:45,896”。逗号后面的是毫秒
%(thread)d	线程ID。可能没有
%(threadName)s	线程名。可能没有
%(process)d	进程ID。可能没有
%(message)s	用户输出的消息

 

import logging

logging.basicConfig(filename='log_test.log',
                    level=logging.DEBUG,
                    #format='%(asctime)s %(message)s',
                    #format='%(asctime)s-%(levelno)s- %(message)s',
                    #format='%(asctime)s-%(levelname)s- %(message)s',
                    #format='%(asctime)s-%(levelname)s-%(pathname)s-%(message)s',
                    #format='%(asctime)s-%(levelname)s-%(filename)s-%(message)s',
                    #format='%(asctime)s-%(levelname)s-%(funcName)s-%(message)s',
                    format='%(asctime)s-%(levelname)s-%(funcName)s-%(lineno)s-%(message)s',
                    datefmt='%m/%d/%Y %I:%M:%S %p')

def sayhi():
    logging.error('from sayhi...')
sayhi()

logging.debug('This message should go to the log file')
logging.info('So should this')
logging.warning('And this,too')

 

#log_test.log

09/29/2018 10:07:06 AM from sayhi...
09/29/2018 10:07:06 AM This message should go to the log file
09/29/2018 10:07:06 AM So should this
09/29/2018 10:07:06 AM And this,too

09/29/2018 10:07:24 AM-40- from sayhi...
09/29/2018 10:07:24 AM-10- This message should go to the log file
09/29/2018 10:07:24 AM-20- So should this
09/29/2018 10:07:24 AM-30- And this,too

09/29/2018 10:07:40 AM-ERROR- from sayhi...
09/29/2018 10:07:40 AM-DEBUG- This message should go to the log file
09/29/2018 10:07:40 AM-INFO- So should this
09/29/2018 10:07:40 AM-WARNING- And this,too

09/29/2018 10:07:49 AM-ERROR-E:/Python/work/myFirstPro/第4章/21—logging模块基础.py-from sayhi...
09/29/2018 10:07:49 AM-DEBUG-E:/Python/work/myFirstPro/第4章/21—logging模块基础.py-This message should go to the log file
09/29/2018 10:07:49 AM-INFO-E:/Python/work/myFirstPro/第4章/21—logging模块基础.py-So should this
09/29/2018 10:07:49 AM-WARNING-E:/Python/work/myFirstPro/第4章/21—logging模块基础.py-And this,too

09/29/2018 10:08:04 AM-ERROR-21—logging模块基础.py-from sayhi...
09/29/2018 10:08:04 AM-DEBUG-21—logging模块基础.py-This message should go to the log file
09/29/2018 10:08:04 AM-INFO-21—logging模块基础.py-So should this
09/29/2018 10:08:04 AM-WARNING-21—logging模块基础.py-And this,too

09/29/2018 10:08:16 AM-ERROR-sayhi-from sayhi...
09/29/2018 10:08:16 AM-DEBUG-<module>-This message should go to the log file
09/29/2018 10:08:16 AM-INFO-<module>-So should this
09/29/2018 10:08:16 AM-WARNING-<module>-And this,too

09/29/2018 10:08:26 AM-ERROR-sayhi-15-from sayhi...
09/29/2018 10:08:26 AM-DEBUG-<module>-18-This message should go to the log file
09/29/2018 10:08:26 AM-INFO-<module>-19-So should this
09/29/2018 10:08:26 AM-WARNING-<module>-20-And this,too

• 常用模块学习—logging模块进阶

  • 日志同时输出到屏幕和文件。

                  Python 使用logging模块记录日志涉及四个主要类，使用官方文档中的概括最为合适：

• • • logger       提供了应用程序可以直接使用的接口；
    • handler     将(logger创建的)日志记录发送到合适的目的输出；
    • filter          提供了细度设备来决定输出哪条日志记录；
    • formatter   决定日志记录的最终输出格式；

  • 他们之间的关系是这样的：

                     

• • 每个组件的主要功能：

• • • logger

  每个程序在输出信息之前都要获得一个Logger。Logger通常对应了程序的模块名，比如聊天工具的图形界面模块可以这样获得它的Logger：

LOG=logging.getLogger(”chat.gui”)

而核心模块可以这样：

LOG=logging.getLogger(”chat.kernel”)

还可以绑定handler和filters

Logger.setLevel(lel):指定最低的日志级别，低于lel的级别将被忽略。debug是最低的内置级别，critical为最高
Logger.addFilter(filt)、Logger.removeFilter(filt):添加或删除指定的filter
Logger.addHandler(hdlr)、Logger.removeHandler(hdlr)：增加或删除指定的handler

Logger.debug()、Logger.info()、Logger.warning()、Logger.error()、Logger.critical()：可以设置的日志级别

• • • handler

 handler对象负责发送相关的信息到指定目的地。Python的日志系统有多种Handler可以使用。有些Handler可以把信息输出到控制台，有些Handler可以把信息输出到文件，还有些 Handler可以把信息发送到网络上。如果觉得不够用，还可以编写自己的Handler。可以通过addHandler()方法添加多个多handler

Handler.setLevel(lel):指定被处理的信息级别，低于lel级别的信息将被忽略
Handler.setFormatter()：给这个handler选择一个格式
Handler.addFilter(filt)、Handler.removeFilter(filt)：新增或删除一个filter对象

每个Logger可以附加多个Handler。接下来我们就来介绍一些常用的Handler：

1、logging.StreamHandler         使用这个Handler可以向类似与sys.stdout或者sys.stderr的任何文件对象(file object)输出信息。


2、logging.FileHandler           和StreamHandler 类似，用于向一个文件输出日志信息。不过FileHandler会帮你打开这个文件。


3、logging.handlers.RotatingFileHandler

这个Handler类似于上面的FileHandler，但是它可以管理文件大小。当文件达到一定大小之后，它会自动将当前日志文件改名，然后创建 一个新的同名日志文件继续输出。比如日志文件是chat.log。当chat.log达到指定的大小之后，RotatingFileHandler自动把 文件改名为chat.log.1。不过，如果chat.log.1已经存在，会先把chat.log.1重命名为chat.log.2。。。最后重新创建 chat.log，继续输出日志信息。它的函数是：

RotatingFileHandler( filename[, mode[, maxBytes[, backupCount]]])


其中 filename 和 mode 两个参数和 FileHandler 一样。

    1、maxBytes     用于指定日志文件的最大文件大小。如果maxBytes为0，意味着日志文件可以无限大，这时上面描述的重命名过程就不会发生。
    2、backupCount  用于指定保留的备份文件的个数。比如，如果指定为2，当上面描述的重命名过程发生时，原有的chat.log.2并不会被更名，而是被删除。


4、logging.handlers.TimedRotatingFileHandler

这个Handler和RotatingFileHandler类似，不过，它没有通过判断文件大小来决定何时重新创建日志文件，而是间隔一定时间就 自动创建新的日志文件。重命名的过程与RotatingFileHandler类似，不过新的文件不是附加数字，而是当前时间。它的函数是：

TimedRotatingFileHandler( filename [,when [,interval [,backupCount]]])

其中filename参数和backupCount参数和RotatingFileHandler具有相同的意义。

interval是时间间隔。

when参数是一个字符串。表示时间间隔的单位，不区分大小写。它有以下取值：
S 秒
M 分
H 小时
D 天
W 每星期（interval==0时代表星期一）
midnight 每天凌晨

• • • formatter 组件

日志的formatter是个独立的组件，可以跟handler组合。

fh = logging.FileHandler("access.log")
formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')

fh.setFormatter(formatter) #把formmater绑定到fh上

'''
logger          提供了应用程序可以直接使用的接口；
handler         将(logger创建的)日志记录发送到合适的目的输出；
filter          提供了细度设备来决定输出哪条日志记录；
formatter       决定日志记录的最终输出格式；
'''

#同时输出到屏幕、文件、不带filter：
import logging

#1、生成 logger 对象
logger = logging.getLogger('web')
#logger.setLevel(logging.INFO)      #全局变量

#2、生成 handler 对象
ch = logging.StreamHandler()
ch.setLevel(logging.DEBUG)         #屏幕    
fh = logging.FileHandler('web.log')
fh.setLevel(logging.WARNING)       #设置日志级别

#2.1、把 handler 对象 绑定到 logger
logger.addHandler(ch)
logger.addHandler(fh)

#3、生成 formatter 对象
#3.1、把 formatter 对象 绑定到 handler
file_formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
console_formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s -%(lineno)d - %(message)s')

ch.setFormatter(console_formatter)
fh.setFormatter(file_formatter)

#进行打印日志
logger.debug('test_log')
#logger.error('test_log 2')
#logger.warning('test_log 2')
logger.info('test_log 2')

#全局console   DEBUG
#屏幕globale    INFO      默认级别是warning
#文件file      Warning

#全局设置为DEBUG后，console handler 设置为INFO，如果输出的日志级别是debug，那就不会在屏幕上打印输出

• 常用模块学习—logging 日志过滤和日志文件自动截取

• • filter 组件

    如果你想对日志内容进行过滤，就可自定义一个filter

    class IgnoreBackupLogFilter(logging.Filter):
        """忽略带db backup 的日志"""
        def filter(self, record): #固定写法
            return   "db backup" not in record.getMessage()
    
    注意：filter函数会返加True or False，logger根据此值决定是否输出此日志

    然后把这个filter添加到logger中

    logger.addFilter(IgnoreBackupLogFilter())

    下面的日志就会把符合filter条件的过滤掉

    logger.debug("test ....")
    logger.info("test info ....")
    logger.warning("start to run db backup job ....")
    logger.error("test error ....")

    #一个同时输出到屏幕、文件、带filter的完成例子：
    
    import logging
    
    class IgnoreBackupLogFilter(logging.Filter):
        """忽略带db backup 的日志"""
        def filter(self, record): #固定写法
            return   "db backup" not in record.getMessage()
    
    #console handler
    ch = logging.StreamHandler()
    ch.setLevel(logging.INFO)
    #file handler
    fh = logging.FileHandler('mysql.log')
    #fh.setLevel(logging.WARNING)
    
    
    #formatter
    formatter = logging.Formatter('%(asctime)s - %(name)s - %(levelname)s - %(message)s')
    #bind formatter to ch
    ch.setFormatter(formatter)
    fh.setFormatter(formatter)
    
    logger = logging.getLogger("Mysql")
    logger.setLevel(logging.DEBUG) #logger 优先级高于其它输出途径的
    
    
    #add handler   to logger instance
    logger.addHandler(ch)
    logger.addHandler(fh)
    
    
    
    #add filter
    logger.addFilter(IgnoreBackupLogFilter())
    
    logger.debug("test ....")
    logger.info("test info ....")
    logger.warning("start to run db backup job ....")
    logger.error("test error ....")

    文件自动截断例子
    
    import logging
    
    from logging import handlers
    
    logger = logging.getLogger(__name__)
    
    log_file = "timelog.log"
    #fh = handlers.RotatingFileHandler(filename=log_file,maxBytes=10,backupCount=3)
    fh = handlers.TimedRotatingFileHandler(filename=log_file,when="S",interval=5,backupCount=3)
    
    
    formatter = logging.Formatter('%(asctime)s %(module)s:%(lineno)d %(message)s')
    
    fh.setFormatter(formatter)
    
    logger.addHandler(fh)
    
    
    logger.warning("test1")
    logger.warning("test12")
    logger.warning("test13")
    logger.warning("test14")