Python：启动批处理文件并读取输出，直到显示特定行并继续

Question

所以我有启动batch服务器的appium文件。

当我开始执行我的batch文件时，我想读取输出，当server运行时我想继续。

我知道appium服务器从这个输出运行时：

Appium REST http interface listener started on 0.0.0.0:4723

目前这就是我所拥有的：

process = subprocess.Popen([r'C:\\appium.bat'])
stdout = process.communicate()[0]
print('STDOUT:{}'.format(stdout))

我想要的是等待60秒或直到这条线出现。如果60 secods通过并且这条线（Appium REST http interface listener started on 0.0.0.0:4723）没有出现我想要提高exception。

我的问题是，当我的服务器启动时，该过程继续运行，所以这永远不会退出并继续下一个代码，我无法杀死appium进程。

有什么建议怎么解决？

Answer 1

以下代码适用于您的案例。首先，它生成一个进程，并等待超时，等待时，它将继续检查进程的输出。然后当模式匹配时，它将中断，否则将引发异常。

import time
import subprocess
import re


proc = subprocess.Popen(['/tmp/test.sh'], stdout=subprocess.PIPE)

timeout = time.time() + 10 # adjust the timeout value here
target = ".*started on .*"

while True:
    if time.time() >= timeout:
        raise Exception("Server wasn't started")
    else:
        output = proc.stdout.readline()
        # read a line of input

        if output == '' and proc.poll() is not None:
            # process is not running anymore, 
            # proc.poll() will return None if process is still running
            raise Exception("Server process has stopped")
        else:
            line = output.decode().strip()
            if re.match(target, line):
                # if the pattern is matched, do something and break
                print("Server has started")
                break
            time.sleep(0.5)

这是我用来测试的bash文件。保存为/tmp/test.sh

#!/bin/bash

echo "TEST"
sleep 1
echo "server has started on 0.0.0.0"

Answer 2

您可以使用时间模块等待

import time

time.sleep(60) # wait for 60 seconds

Answer 3

你可以用signal.alarm做到这一点，

import signal
import time
import subprocess

def handler(signum, stack):
    raise Exception("It didn't happen in time...") # raise exception if it didn't come up within the time frame 

signal.signal(signal.SIGALRM, handler)
signal.alarm(60)
process = subprocess.Popen([r'C:\\appium.bat'])
stdout = process.communicate()[0] # assuming this blocks
print('STDOUT:{}'.format(stdout))
signal.alarm(0) # turn of the alarm, if it came up within 60 seconds

如果.communicate()不是blocking，那么，

import subprocess
process = subprocess.Popen([r'C:\\appium.bat'])
stdout = process.communicate()[0] # non blocking ?
print('STDOUT:{}'.format(stdout))
time.sleep(60)
if 'Appium REST http interface listener started' not in stdout:
    raise Exception("It didn't come up in time...")