python 3.5-腳本終止后subprocess.run仍在運行

Question

為什么當我從該腳本運行subprocess.run('knife ec2 server create...', shell=True, check=True)命令時，我用ctrl+c終止python腳本后，控件返回到終端會話，但是幾分鍾/秒后，shell命令再次出現在終端會話中，並且subprocess.run的shell命令仍在運行？

我想我在os.system了同樣的問題，例如os.system('ping 8.8.8.8') 。

^C

Waiting for EC2 to create the instance.....^CTraceback (most recent call last):
  File "t.py", line 177, in <module>
    subprocess.run(command, shell=True, check=True)
  File "/usr/lib/python3.5/subprocess.py", line 695, in run
    stdout, stderr = process.communicate(input, timeout=timeout)
  File "/usr/lib/python3.5/subprocess.py", line 1064, in communicate
    self.wait()
  File "/usr/lib/python3.5/subprocess.py", line 1658, in wait
    (pid, sts) = self._try_wait(0)
  File "/usr/lib/python3.5/subprocess.py", line 1608, in _try_wait
    (pid, sts) = os.waitpid(self.pid, wait_flags)
KeyboardInterrupt
$ ..............................................................................done

SSH Target Address: ec2()
Doing old-style registration with the validation key at /etc/chef/validation.pem...
Delete your validation key in order to use your user credentials instead

我也嘗試了以下代碼，但出現錯誤：

command = ('knife ec2 server create -N ' + fullname + ' -f ' + instance_type + ' -i ' + pem_file)...

p = subprocess.Popen(command, shell=True, stderr=subprocess.PIPE)
while True:
    out = p.stderr.read(1)
    if out == '' and p.poll() != None:
        break
    if out != '':
        sys.stdout.write(out)
        sys.stdout.flush()

錯誤：

`sys.stdout.write(out) TypeError: write() argument must be str, not bytes'

有沒有一種簡單的方法可以像Ruby通過system()使用python運行shell命令？

謝謝

Answer 1

子流程模塊會產生一個新流程。 當您向python代碼發送CTRL + C信號時，您已經存在python應用程序，但是子進程仍在運行，並且您的代碼決定不等待該進程完成。

嘗試在代碼中捕獲Ctrl + C信號，然后在存在您的應用程序之前使用Popen終止調用來結束子進程。

import shlex, subprocess
command_line = input()

args = shlex.split(command_line)
print(args)

p = subprocess.Popen(args) # Success!

Popen和子流程文檔

這是終止調用的API文檔：

終結者

編輯這是python 2.7的示例演示代碼，打印strout的代碼部分不適用於ping，因為它仍會將ping結果輸出到終端，但我將其放置在此處以供參考。

import subprocess
import signal
import sys

command = 'ping {0}'.format('8.8.8.8')
p = subprocess.Popen(command, shell=True, stderr=subprocess.PIPE)

# callback for the Ctrl+C signal
def signal_handler(signal, frame):
    print("CTRL+C received")
    p.kill() # or terminate
    p.wait()
    sys.exit(0)    

# register signal with the callback
signal.signal(signal.SIGINT, signal_handler)

# white subprocess hasn't finished
while p.poll() is None:
    out = p.communicate()
    print(out.stdoutdata)