python - 合并并同步 stdout 和 stderr？

Question

假设我正在使用 python 脚本运行 exe:

subprocess.call(cmdArgs,stdout=outf, stderr=errf)

当 outf 和 errf 是文本文件的文件描述符时。

有什么方法可以在其上生成一个包含 stdout 和 stderr 的合并和同步文本文件吗？它应该用时间和来源(我们的/错误的)格式化。

谢谢

Answer 1

这有点棘手，因为您需要在子进程运行时轮询其 stdout 和 stderr 文件描述符，以获得准确的时间戳。您还需要将输出分成行列表，以便可以轻松地合并和排序最终结果。您可以在读取两个流时轻松合并它们，但这不是问题的一部分。

我写得很快，但它可以变得更简洁、更紧凑:

import datetime
import os
import select
import subprocess

class Stream(object):

    def __init__(self, name, impl):
        self._name = name
        self._impl = impl
        self._buf = ''
        self._rows = []

    def fileno(self):
        "Pass-through for file descriptor."
        return self._impl.fileno()

    def read(self, drain=0):
        "Read from the file descriptor. If 'drain' set, read until EOF."
        while self._read() is not None:
            if not drain:
                break

    def _read(self):
        "Read from the file descriptor"
        fd = self.fileno()
        buf = os.read(fd, 4096)
        if not buf:
            return None
        if '\n' not in buf:
            self._buf += buf
            return []

        # prepend any data previously read, then split into lines and format
        buf = self._buf + buf
        tmp, rest = buf.rsplit('\n', 1)
        self._buf = rest
        now = datetime.datetime.now().isoformat()
        rows = tmp.split('\n')
        self._rows += [(now, '%s %s: %s' % (self._name, now, r)) for r in rows]

def run(cmd, timeout=0.1):
    """
    Run a command, read stdout and stderr, prefix with timestamp, and
    return a dict containing stdout, stderr and merged.
    """
    PIPE = subprocess.PIPE
    proc = subprocess.Popen(cmd, stdout=PIPE, stderr=PIPE)
    streams = [
        Stream('stdout', proc.stdout),
        Stream('stderr', proc.stderr)
        ]
    def _process(drain=0):
        res = select.select(streams, [], [], timeout)
        for stream in res[0]:
            stream.read(drain)

    while proc.returncode is None:
        proc.poll()
        _process()
    _process(drain=1)

    # collect results, merge and return
    result = {}
    temp = []
    for stream in streams:
        rows = stream._rows
        temp += rows
        result[stream._name] = [r[1] for r in rows]
    temp.sort()
    result['merged'] = [r[1] for r in temp]
    return result

res = run(['ls', '-l', '.', 'xyzabc'])
for key in ('stdout', 'stderr', 'merged'):
    print 
    print '\n'.join(res[key])
    print '-'*40

示例输出:

stdout 2011-03-03T19:30:44.838145: .:
stdout 2011-03-03T19:30:44.838145: total 0
stdout 2011-03-03T19:30:44.838338: -rw-r--r-- 1 pat pat 0 2011-03-03 19:30 bar
stdout 2011-03-03T19:30:44.838518: -rw-r--r-- 1 pat pat 0 2011-03-03 19:30 foo
----------------------------------------

stderr 2011-03-03T19:30:44.837189: ls: cannot access xyzabc: No such file or directory
----------------------------------------

stderr 2011-03-03T19:30:44.837189: ls: cannot access xyzabc: No such file or directory
stdout 2011-03-03T19:30:44.838145: .:
stdout 2011-03-03T19:30:44.838145: total 0
stdout 2011-03-03T19:30:44.838338: -rw-r--r-- 1 pat pat 0 2011-03-03 19:30 bar
stdout 2011-03-03T19:30:44.838518: -rw-r--r-- 1 pat pat 0 2011-03-03 19:30 foo
----------------------------------------