19091802使用subprocess

最新推荐文章于 2024-07-03 22:20:54 发布

原创最新推荐文章于 2024-07-03 22:20:54 发布 · 135 阅读

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本文深入探讨了Python中使用subprocess模块管理子进程的方法，包括call、check_call、check_output及Popen函数的详细应用。通过实例展示了如何处理子进程的输出、错误以及超时情况，特别关注了Popen在复杂场景下的阻塞问题解决方案。

subprocess.call()

subprocess.check_out()

subprocess.check_output()

subprocess.Popen()

subprocess.call()

res = subprocess.call('ls -l', shell = True)
print  'res:', res

subprocess.check_out()

import subprocess
try:
    res = subprocess.check_call(['ls', '('])
    print  'res:', res
except subprocess.CalledProcessError, exc:
    print 'returncode:', exc.returncode
    print 'cmd:', exc.cmd
    print 'output:', exc.output

subprocess.check_output()

import subprocess
try:
    res = subprocess.check_output('ls xxx',
                    stderr = subprocess.STDOUT,
                    shell = True)
    print  'res:', res
except subprocess.CalledProcessError, exc:
    print 'returncode:', exc.returncode
    print 'cmd:', exc.cmd
    print 'output:', exc.output

subprocess.Popen()

阻塞问题：

#!/usr/bin/python
# -*- coding: utf-8 -*-
import subprocess
from threading import Timer
import os

class test(object):
    def __init__(self):
        self.stdout = []
        self.stderr = []
        self.timeout = 10
        self.is_timeout = False
        pass
    
    def timeout_callback(self, p):
        self.is_timeout = True
        print 'exe time out call back'
        print p.pid
        try:
            os.killpg(p.pid, signal.SIGKILL)
        except Exception as error:
            print error

    def run(self):
        cmd = ['bash', '/home/zhangxin/work/baofabu/test.sh']
        #p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
        p = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE, preexec_fn=os.setsid)
        my_timer = Timer(self.timeout, self.timeout_callback, [p])
        my_timer.start()
        try:
            print "start to count timeout; timeout set to be %d \n" % (self.timeout,)
            for line in iter(p.stdout.readline, b''):
                print line
                if self.is_timeout:
                    break
            for line in iter(p.stderr.readline, b''):
                print line
                if self.is_timeout:
                    break
        finally:
            my_timer.cancel()
            p.stdout.close()
            p.stderr.close()
            p.kill()
            p.wait()

其中test.sh:

#!/bin/bash
ping   www.baidu.com
echo $$

像threading那样执行python函数：

import os
import signal
import subprocess
import tempfile
import time
import sys


def show_setting_prgrp():
    print('Calling os.setpgrp() from {}'.format(os.getpid()))
    os.setpgrp()
    print('Process group is now {}'.format(
        os.getpid(), os.getpgrp()))
    sys.stdout.flush()

# 这次的重点关注是这里
script = '''#!/bin/sh
echo "Shell script in process $$"
set -x
python signal_child.py
'''
script_file = tempfile.NamedTemporaryFile('wt')
script_file.write(script)
script_file.flush()

proc = subprocess.Popen(
    ['sh', script_file.name],
    preexec_fn=show_setting_prgrp,
)
print('PARENT      : Pausing before signaling {}...'.format(
    proc.pid))
sys.stdout.flush()
time.sleep(1)
print('PARENT      : Signaling process group {}'.format(
    proc.pid))
sys.stdout.flush()
os.killpg(proc.pid, signal.SIGUSR1)
time.sleep(3)