运行子流程并将输出打印到日志记录 [英] Run subprocess and print output to logging

问题描述

我正在寻找从python调用shell脚本，并使用日志记录将其stdout和stderr写入文件的方法.这是我的代码:

I am looking for the way to call shell scripts from python and write their stdout and stderr to file using logging. Here is my code:

import logging
import tempfile
import shlex
import os

def run_shell_command(command_line):
    command_line_args = shlex.split(command_line)

    logging.info('Subprocess: \"' + command_line + '\"')

    process_succeeded = True
    try:
        process_output_filename = tempfile.mktemp(suffix = 'subprocess_tmp_file_')
        process_output = open(process_output_filename, 'w')

        command_line_process = subprocess.Popen(command_line_args,\
                                                stdout = process_output,\
                                                stderr = process_output)
        command_line_process.wait()
        process_output.close()

        process_output = open(process_output_filename, 'r')
        log_subprocess_output(process_output)
        process_output.close()

        os.remove(process_output_filename)
    except:
        exception = sys.exc_info()[1]
        logging.info('Exception occured: ' + str(exception))
        process_succeeded = False

    if process_succeeded:
        logging.info('Subprocess finished')
    else:
        logging.info('Subprocess failed')

    return process_succeeded

我敢肯定，有一种方法可以做到，而无需创建用于存储进程输出的临时文件.有什么想法吗?

And I am sure that there is the way to do it without creating temporary file to store process output. Any ideas?

推荐答案

我敢肯定，有一种方法可以在不创建临时文件的情况下进行 文件来存储过程输出

I am sure that there is the way to do it without creating temporary file to store process output

您只需要检查 Popen 的文档，特别是关于stdout和stderr:

stdin，stdout和stderr指定执行的程序的标准 输入，标准输出和标准错误文件句柄. 有效值为PIPE，即现有文件描述符(正数 整数)，一个现有文件对象和None. PIPE表示 应该创建到孩子的新管道.使用默认设置 None，将不会发生重定向；孩子的文件句柄将是 从父级继承.另外，stderr可以是STDOUT， 表示子进程的stderr数据应 被捕获到与stdout相同的文件句柄中.

stdin, stdout and stderr specify the executed program’s standard input, standard output and standard error file handles, respectively. Valid values are PIPE, an existing file descriptor (a positive integer), an existing file object, and None. PIPE indicates that a new pipe to the child should be created. With the default settings of None, no redirection will occur; the child’s file handles will be inherited from the parent. Additionally, stderr can be STDOUT, which indicates that the stderr data from the child process should be captured into the same file handle as for stdout.

因此您可以看到可以使用文件对象，也可以使用PIPE值.这使您可以使用 communicate() 方法来检索输出:

So you can see that you can either use a file object, or the PIPE value. This allows you to use the communicate() method to retrieve the output:

from StringIO import StringIO
process = subprocess.Popen(arguments, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
output, error = process.communicate()
log_subprocess_output(StringIO(output))

---

我会将您的代码重写为:

---

I'd rewrite your code as:

import shlex
import logging
import subprocess
from StringIO import StringIO

def run_shell_command(command_line):
    command_line_args = shlex.split(command_line)

    logging.info('Subprocess: "' + command_line + '"')

    try:
        command_line_process = subprocess.Popen(
            command_line_args,
            stdout=subprocess.PIPE,
            stderr=subprocess.STDOUT,
        )

        process_output, _ =  command_line_process.communicate()

        # process_output is now a string, not a file,
        # you may want to do:
        # process_output = StringIO(process_output)
        log_subprocess_output(process_output)
    except (OSError, CalledProcessError) as exception:
        logging.info('Exception occured: ' + str(exception))
        logging.info('Subprocess failed')
        return False
    else:
        # no exception was raised
        logging.info('Subprocess finished')

    return True

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