python:连续读取文件，即使它已经被logrotated

问题描述

我有一个简单的python脚本，可在其中连续读取日志文件(与tail -f相同)

I have a simple python script, where I read logfile continuosly (same as tail -f)

while True:
    line = f.readline()
    if line:
        print line,
    else:
        time.sleep(0.1)

通过logrotate旋转日志文件后，如何确保仍可以读取日志文件?

How can I make sure that I can still read the logfile, after it has been rotated by logrotate?

即我需要做与tail -F一样的事情.

i.e. I need to do the same what tail -F would do.

我正在使用python 2.7

推荐答案

只要您只打算在Unix上这样做，最可靠的方法可能就是检查，以使打开的文件仍引用相同的 i节点作为名称，如果情况不再如此，请重新打开它.您可以在st_ino字段中从os.stat和os.fstat获取文件的编号.

As long as you only plan to do this on Unix, the most robust way is probably to check so that the open file still refers to the same i-node as the name, and reopen it when that is no longer the case. You can get the i-number of the file from os.stat and os.fstat, in the st_ino field.

它可能看起来像这样:

import os, sys, time

name = "logfile"
current = open(name, "r")
curino = os.fstat(current.fileno()).st_ino
while True:
    while True:
        buf = current.read(1024)
        if buf == "":
            break
        sys.stdout.write(buf)
    try:
        if os.stat(name).st_ino != curino:
            new = open(name, "r")
            current.close()
            current = new
            curino = os.fstat(current.fileno()).st_ino
            continue
    except IOError:
        pass
    time.sleep(1)

我怀疑这在Windows上是否有效，但是由于您使用的是tail的说法，所以我想这不是问题. :)

I doubt this works on Windows, but since you're speaking in terms of tail, I'm guessing that's not a problem. :)

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