Signal communication programming, Wang Ming Learning Learn

Signal Communication Programming

In the Linux system, the signal (signal) is also the oldest inter-process communication mechanism.

First, the signal type

All the signals supported by the Linux system are defined in/usr/include/asm/signal.h (display), where the common signals are:

SIGKILL: Kill Process

SIGSTOP: Pausing a process

SIGCHLD: Used to notify the parent process when a child process stops or ends

Second, function learning

2.1 Sending a signal

Name of 2.1.1 function

Kill

2.1.2 Function prototype

int Kill (pid_t pid,int SIG);

2.1.3 Function function

Send a signal to a process

2.1.4 Owning header file

<sys/types.h> <singl.h>

2.1.5 return value

Success: return 0

Failure: Return-1

2.1.6 parameter Description

Pid:if (pid>0), the PID parameter points to the process of receiving the signal

SIG: Used to indicate the signal we're sending.

2.2 Processing Signal

Name of 2.2.1 function

Signal

2.2.2 Function prototype

typedef void (*sighandler_t) (int);

sighandler_t signal (int signum,sighandler_t handler);

2.2.3 function function

Set the signal processing mode

2.2.4 Owning header file

<signal.h>

2.2.5 return value

Success: Returns a pointer to the handler function

Failed: Return Sig_err

2.2.6 parameter Description

Signum: The signal to be processed

Handler: The corresponding signal processing method, can be value (3 kinds)

Sig_ign: Ignoring this signal does not handle

SIG_DFL: Handing over to kernel processing

User-defined functions: User-defined function handling

Signal communication programming, Wang Ming Learning Learn