如何从python程序发送信号？

Question

我有这样的代码，它会监听USR1信号

import signal 
import os 
import time 

def receive_signal(signum, stack): 
    print 'Received:', signum 

signal.signal(signal.SIGUSR1, receive_signal) 
signal.signal(signal.SIGUSR2, receive_signal) 

print 'My PID is:', os.getpid() 

while True: 
    print 'Waiting...' 
    time.sleep(3) 

这工作时，我发出信号，kill -USR1 pid

但我怎么可以从发送上面的Python脚本中相同的信号，使10秒后它自动发送USR1也收到它，我不必打开两个终端来检查它？

Answer 1

如果你愿意搭上SIGALRM，而不是SIGUSR1，请尝试：

signal.alarm(10) 

否则，你需要启动另一个线程：

import time, os, signal, threading 
pid = os.getpid() 
thread = threading.Thread(
    target=lambda: (
    time.sleep(10), 
    os.kill(pid, signal.SIGUSR1))) 
thread.start() 

因此，该程序：

import signal 
import os 
import time 

def receive_signal(signum, stack): 
    print 'Received:', signum 

signal.signal(signal.SIGUSR1, receive_signal) 
signal.signal(signal.SIGUSR2, receive_signal) 
signal.signal(signal.SIGALRM, receive_signal) # <-- THIS LINE ADDED 

print 'My PID is:', os.getpid() 

signal.alarm(10)        # <-- THIS LINE ADDED 

while True: 
    print 'Waiting...' 
    time.sleep(3) 

产生此输出：

$ python /tmp/x.py 
My PID is: 3029 
Waiting... 
Waiting... 
Waiting... 
Waiting... 
Received: 14 
Waiting... 
Waiting... 

Answer 2

您可以使用os.kill()：

os.kill(os.getpid(), signal.SIGUSR1) 

把你的代码，这在任何地方，你想从发送信号。