如何在 Python 中将 stdout 和 stderr 重定向到记录器
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How to redirect stdout and stderr to logger in Python
提问by orenma
I have a logger that has a RotatingFileHandler.
I want to redirect all Stdoutand Stderrto the logger.
How to do so?
我有一个记录器，它有一个RotatingFileHandler. 我想重定向所有Stdout与Stderr该记录器。怎么做？
回答by Vinay Sajip
If it's an all-Python system (i.e. no C libraries writing to fds directly, as Ignacio Vazquez-Abrams asked about) then you might be able to use an approach as suggested here:
如果它是一个全 Python 系统（即没有直接写入 fds 的 C 库，正如 Ignacio Vazquez-Abrams 所问的那样），那么您可以使用此处建议的方法：
class LoggerWriter:
def __init__(self, logger, level):
self.logger = logger
self.level = level
def write(self, message):
if message != '\n':
self.logger.log(self.level, message)
and then set sys.stdoutand sys.stderrto LoggerWriterinstances.
然后设置sys.stdout和sys.stderr到LoggerWriter实例。
回答by Cameron Gagnon
Not enough rep to comment, but I wanted to add the version of this that worked for me in case others are in a similar situation.
没有足够的代表发表评论，但我想添加对我有用的版本，以防其他人处于类似情况。
class LoggerWriter:
def __init__(self, level):
# self.level is really like using log.debug(message)
# at least in my case
self.level = level
def write(self, message):
# if statement reduces the amount of newlines that are
# printed to the logger
if message != '\n':
self.level(message)
def flush(self):
# create a flush method so things can be flushed when
# the system wants to. Not sure if simply 'printing'
# sys.stderr is the correct way to do it, but it seemed
# to work properly for me.
self.level(sys.stderr)
and this would look something like:
这看起来像：
log = logging.getLogger('foobar')
sys.stdout = LoggerWriter(log.debug)
sys.stderr = LoggerWriter(log.warning)
回答by gerardw
With flush added to Vinay Sajip's answer:
在 Vinay Sajip 的回答中添加了flush：
class LoggerWriter:
def __init__(self, logger, level):
self.logger = logger
self.level = level
def write(self, message):
if message != '\n':
self.logger.log(self.level, message)
def flush(self):
pass
回答by shellcat_zero
All of the prior answers seem to have problems adding extra newlines where they aren't needed. The solution that works best for me is from http://www.electricmonk.nl/log/2011/08/14/redirect-stdout-and-stderr-to-a-logger-in-python/, where he demonstrates how send both stdout and stderr to the logger:
所有先前的答案似乎都有问题，在不需要的地方添加额外的换行符。最适合我的解决方案来自http://www.electricmonk.nl/log/2011/08/14/redirect-stdout-and-stderr-to-a-logger-in-python/，他演示了如何将 stdout 和 stderr 都发送到记录器：
import logging
import sys
class StreamToLogger(object):
"""
Fake file-like stream object that redirects writes to a logger instance.
"""
def __init__(self, logger, log_level=logging.INFO):
self.logger = logger
self.log_level = log_level
self.linebuf = ''
def write(self, buf):
for line in buf.rstrip().splitlines():
self.logger.log(self.log_level, line.rstrip())
logging.basicConfig(
level=logging.DEBUG,
format='%(asctime)s:%(levelname)s:%(name)s:%(message)s',
filename="out.log",
filemode='a'
)
stdout_logger = logging.getLogger('STDOUT')
sl = StreamToLogger(stdout_logger, logging.INFO)
sys.stdout = sl
stderr_logger = logging.getLogger('STDERR')
sl = StreamToLogger(stderr_logger, logging.ERROR)
sys.stderr = sl
print "Test to standard out"
raise Exception('Test to standard error')
The output looks like:
输出看起来像：
2011-08-14 14:46:20,573:INFO:STDOUT:Test to standard out
2011-08-14 14:46:20,573:ERROR:STDERR:Traceback (most recent call last):
2011-08-14 14:46:20,574:ERROR:STDERR: File "redirect.py", line 33, in
2011-08-14 14:46:20,574:ERROR:STDERR:raise Exception('Test to standard error')
2011-08-14 14:46:20,574:ERROR:STDERR:Exception
2011-08-14 14:46:20,574:ERROR:STDERR::
2011-08-14 14:46:20,574:ERROR:STDERR:Test to standard error
Note that self.linebuf = '' is where the flush is being handled, rather than implementing a flush function.
请注意 self.linebuf = '' 是处理刷新的地方，而不是实现刷新功能。
回答by QuadX
You can use redirect_stdout context manager:
您可以使用 redirect_stdout 上下文管理器：
import logging
from contextlib import redirect_stdout
logging.basicConfig(stream=sys.stdout, level=logging.DEBUG)
logging.write = lambda msg: logging.info(msg) if msg != '\n' else None
with redirect_stdout(logging):
print('Test')
or like this
或者像这样
import logging
from contextlib import redirect_stdout
logger = logging.getLogger('Meow')
logger.setLevel(logging.INFO)
formatter = logging.Formatter(
fmt='[{name}] {asctime} {levelname}: {message}',
datefmt='%m/%d/%Y %H:%M:%S',
style='{'
)
ch = logging.StreamHandler()
ch.setLevel(logging.INFO)
ch.setFormatter(formatter)
logger.addHandler(ch)
logger.write = lambda msg: logger.info(msg) if msg != '\n' else None
with redirect_stdout(logger):
print('Test')
回答by Toni Homedes i Saun
As an evolution to Cameron Gagnon's response, I've improved the LoggerWriterclass to:
作为 Cameron Gagnon 回应的演变，我已将LoggerWriter课程改进为：
class LoggerWriter(object):
def __init__(self, writer):
self._writer = writer
self._msg = ''
def write(self, message):
self._msg = self._msg + message
while '\n' in self._msg:
pos = self._msg.find('\n')
self._writer(self._msg[:pos])
self._msg = self._msg[pos+1:]
def flush(self):
if self._msg != '':
self._writer(self._msg)
self._msg = ''
now uncontrolled exceptions look nicer:
现在不受控制的异常看起来更好：
2018-07-31 13:20:37,482 - ERROR - Traceback (most recent call last):
2018-07-31 13:20:37,483 - ERROR - File "mf32.py", line 317, in <module>
2018-07-31 13:20:37,485 - ERROR - main()
2018-07-31 13:20:37,486 - ERROR - File "mf32.py", line 289, in main
2018-07-31 13:20:37,488 - ERROR - int('')
2018-07-31 13:20:37,489 - ERROR - ValueError: invalid literal for int() with base 10: ''
