python - Python - 捕获所有信号

Question

在 Linux 下的 python 2.6 中，我可以使用以下方法来处理 TERM 信号：

import signal
def handleSigTERM():
    shutdown()
signal.signal(signal.SIGTERM, handleSigTERM)    

有没有办法为进程接收到的所有信号设置一个处理程序，而不是一次设置一个？

Answer 1

您可以遍历信号模块中的信号并进行设置。

for i in [x for x in dir(signal) if x.startswith("SIG")]:
  try:
    signum = getattr(signal,i)
    signal.signal(signum,sighandler)
  except (OSError, RuntimeError) as m: #OSError for Python3, RuntimeError for 2
    print ("Skipping {}".format(i))

Answer 2

从 Python 3.5 开始，信号常量被定义为 enum，从而实现了更好的方法：

import signal

catchable_sigs = set(signal.Signals) - {signal.SIGKILL, signal.SIGSTOP}
for sig in catchable_sigs:
    signal.signal(sig, print)  # Substitute handler of choice for `print`

Answer 3

如果您想摆脱尝试，只需忽略无法捕获的信号即可。

#!/usr/bin/env python
# https://stackoverflow.com/questions/2148888/python-trap-all-signals
import os
import sys
import time
import signal

SIGNALS_TO_NAMES_DICT = dict((getattr(signal, n), n) \
    for n in dir(signal) if n.startswith('SIG') and '_' not in n )


def receive_signal(signum, stack):
    if signum in [1,2,3,15]:
        print 'Caught signal %s (%s), exiting.' % (SIGNALS_TO_NAMES_DICT[signum], str(signum))
        sys.exit()
    else:
        print 'Caught signal %s (%s), ignoring.' % (SIGNALS_TO_NAMES_DICT[signum], str(signum))

def main():
    uncatchable = ['SIG_DFL','SIGSTOP','SIGKILL']
    for i in [x for x in dir(signal) if x.startswith("SIG")]:
        if not i in uncatchable:
            signum = getattr(signal,i)
            signal.signal(signum,receive_signal)
    print('My PID: %s' % os.getpid())
    while True:
        time.sleep(1)
main()

Answer 4

适用于 Windows 10 和 Python 3.7：

import signal
import time

def sighandler(signal,frame):
    print("signal",sig,frame)
    return

catchable_sigs = set(signal.Signals)
for sig in catchable_sigs:
    try:
        signal.signal(sig, sighandler)
        print("Setting ",sig)
        print ("value {}".format(sig))
    except (ValueError, OSError, RuntimeError) as m:
        print("Skipping ",sig)
        print ("Value {}".format(sig))


# press some keys or issue kill
x = 0
while x < 5:
    time.sleep(4)
    x += 1

结果：

Skipping  Signals.CTRL_C_EVENT
Value 0
Skipping  Signals.CTRL_BREAK_EVENT
Value 1
Setting  Signals.SIGINT
value 2
Setting  Signals.SIGILL
value 4
Setting  Signals.SIGFPE
value 8
Setting  Signals.SIGSEGV
value 11
Setting  Signals.SIGTERM
value 15
Setting  Signals.SIGBREAK
value 21
Setting  Signals.SIGABRT
value 22

Answer 5

这是一种 2/3 兼容的方式，它没有其他方法那么多的陷阱：

from itertools import count
import signal

def set_all_signal_signals(handler):
    """Set all signals to a particular handler."""
    for signalnum in count(1):
        try:
            signal.signal(signalnum, handler)
            print("set {}".format(signalnum))
        except (OSError, RuntimeError):
            # Invalid argument such as signals that can't be blocked
            pass
        except ValueError:
            # Signal out of range
            break

由于signalnum只是一个数字，因此迭代 1 到超出范围，将信号设置为特定句柄。

Answer 6

对于 Python 3：

for sig in signal.Signals:
    try:
        signal.signal(sig, sighandler)
    except OSError:
        print('Skipping', sig)

Answer 7

在 Python3.8 中，我们有了一个新函数signal.valid_signals() https://docs.python.org/3/library/signal.html#signal.valid_signals

import signal
for sig in signal.valid_signals():
    print(f"{sig:2d}",sig)

Answer 8

该代码在当前版本的 python 中不起作用。有许多以 SIG 开头的变量具有相同的值。例如，SIGHUP 和 SIG_UNBLOCK 都是 1。我能想到的获得实际信号列表的唯一方法就是自己制作。

from signal import *    
signals = {
        SIGABRT: 'SIGABRT',
        SIGALRM: 'SIGALRM',
        SIGBUS: 'SIGBUS',
        SIGCHLD: 'SIGCHLD',
        SIGCONT: 'SIGCONT',
        SIGFPE: 'SIGFPE',
        SIGHUP: 'SIGHUP',
        SIGILL: 'SIGILL',
        SIGINT: 'SIGINT',
        SIGPIPE: 'SIGPIPE',
        SIGPOLL: 'SIGPOLL',
        SIGPROF: 'SIGPROF',
        SIGQUIT: 'SIGQUIT',
        SIGSEGV: 'SIGSEGV',
        SIGSYS: 'SIGSYS',
        SIGTERM: 'SIGTERM',
        SIGTRAP: 'SIGTRAP',
        SIGTSTP: 'SIGTSTP',
        SIGTTIN: 'SIGTTIN',
        SIGTTOU: 'SIGTTOU',
        SIGURG: 'SIGURG',
        SIGUSR1: 'SIGUSR1',
        SIGUSR2: 'SIGUSR2',
        SIGVTALRM: 'SIGVTALRM',
        SIGXCPU: 'SIGXCPU',
        SIGXFSZ: 'SIGXFSZ',
        }

for num in signals:
    signal(num, h)