Detailed explanation of Python signals

The concept of signal

Signal (signal) - The method of communication between processes is a software interrupt. Once a process receives a signal, it interrupts the original program execution flow to handle the signal.

Several common signals:

SIGINT Terminate process Interrupt process (control+c)

SIGQUIT Exit process

SIGTERM Terminate process Software termination signal (default Signal)

SIGKILL Terminate process Kill process

SIGALRM Alarm signal

For example, when pressing control+c to terminate the process, do Some processing, the code is as follows:

import signal

def fun(sig, stack_frame):
　print 'eixt %d, %s' % (sig, stack_frame)
Exit(1)

signal.signal(signal.SIGINT, fun)

signal.signal(signal.SIGINT, fun) is used to register Semaphore processingFunction,

The first parameter is the semaphore, and the second parameter can be passed to a function.

This function has two parameters by default, The first parameter sig represents the received semaphore, and the second stack_frame can be understood as the call stack that generates the interrupt semaphore sig.

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