日志记录、StreamHandler 和标准流 [英] Logging, StreamHandler and standard streams

问题描述

我不知道如何将信息级消息记录到标准输出，但其他所有信息都记录到标准错误.我已经读过这个 http://docs.python.org/library/logging.html.有什么建议吗?

解决方案

以下脚本，log1.py:

导入日志，sys类 SingleLevelFilter(logging.Filter):def __init__(self, passlevel, reject):self.passlevel = passlevelself.reject = 拒绝def过滤器(自我，记录):如果自我拒绝:返回 (record.levelno != self.passlevel)别的:返回(记录.levelno == self.passlevel)h1 = logging.StreamHandler(sys.stdout)f1 = SingleLevelFilter(logging.INFO, False)h1.addFilter(f1)rootLogger = logging.getLogger()rootLogger.addHandler(h1)h2 = logging.StreamHandler(sys.stderr)f2 = SingleLevelFilter(logging.INFO, True)h2.addFilter(f2)rootLogger.addHandler(h2)logger = logging.getLogger("my.logger")logger.setLevel(logging.DEBUG)logger.debug("一条调试消息")logger.info("一条信息消息")logger.warning("警告信息")logger.error("错误信息")logger.critical("一条关键信息")

运行时，产生以下结果.

<前>C: emp>log1.py一条调试消息一条 INFO 消息警告信息错误信息一条重要信息

如您所料，因为在终端上 sys.stdout 和 sys.stderr 是相同的.现在，让我们将标准输出重定向到一个文件，tmp:

<前>C: emp>log1.py >tmp一条调试消息警告信息错误信息一条重要信息

所以 INFO 消息还没有打印到终端 - 但是指向 sys.stderr 已 的消息已打印.让我们看看 tmp 中的内容:

<前>C: emp> 输入 tmp一条 INFO 消息

所以这种方法似乎可以满足您的需求.

I can't figure out how to log info-level messages to stdout, but everything else to stderr. I already read this http://docs.python.org/library/logging.html. Any suggestion?

解决方案

The following script, log1.py:

import logging, sys

class SingleLevelFilter(logging.Filter):
    def __init__(self, passlevel, reject):
        self.passlevel = passlevel
        self.reject = reject

    def filter(self, record):
        if self.reject:
            return (record.levelno != self.passlevel)
        else:
            return (record.levelno == self.passlevel)

h1 = logging.StreamHandler(sys.stdout)
f1 = SingleLevelFilter(logging.INFO, False)
h1.addFilter(f1)
rootLogger = logging.getLogger()
rootLogger.addHandler(h1)
h2 = logging.StreamHandler(sys.stderr)
f2 = SingleLevelFilter(logging.INFO, True)
h2.addFilter(f2)
rootLogger.addHandler(h2)
logger = logging.getLogger("my.logger")
logger.setLevel(logging.DEBUG)
logger.debug("A DEBUG message")
logger.info("An INFO message")
logger.warning("A WARNING message")
logger.error("An ERROR message")
logger.critical("A CRITICAL message")

when run, produces the following results.

C:	emp>log1.py
A DEBUG message
An INFO message
A WARNING message
An ERROR message
A CRITICAL message

As you'd expect, since on a terminal sys.stdout and sys.stderr are the same. Now, let's redirect stdout to a file, tmp:

C:	emp>log1.py >tmp
A DEBUG message
A WARNING message
An ERROR message
A CRITICAL message

So the INFO message has not been printed to the terminal - but the messages directed to sys.stderr have been printed. Let's look at what's in tmp:

C:	emp>type tmp
An INFO message

So that approach appears to do what you want.

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