C Standard Library – <signal.h>

May 11, 2021 C

1. C Standard Library - slt;signal.h.gt;

C Standard Library - slt;signal.h.gt;

Brief introduction

The signal.h header file defines a variable type sig_atomic_t, two function calls, and some macros to handle the different signals reported during program execution.

Library variables

Here are the types of variables defined in the header file signal.h:

Serial number	Variable & description
1	sig_atomic_t This is int Type, use as variables in the signal handler.It is an integer type of an object that can be accessed as an atomic entity, even if there is an asynchronous signal, the object can be accessed as an atomic entity.

Library macros

The following are the macros defined in the header file signal.h, which will be used in the following two functions. SIG_ the function of the signal by using the macro with the signal function.

Serial number	Macro & Description
1	SIG_DFL The default signal handler.
2	SIG_ERR Represents a signal error.
3	SIG_IGN Ignore the signal.

SIG macros are signal codes that represent a variety of conditions:

Serial number	Macro & Description
1	SIGABRT The program is extremely terminated.
2	SIGFPE The arithmetic operation is wrong, such as 0 or overflow.
3	SIGILL Illegal functions, such as illegal instructions.
4	SIGINT Interrupt signal, such as CTRL-C.
5	SIGSEGV Illegal access memory, such as accessing the memory cell that does not exist.
6	SIGTERM The termination request signal is sent to this program.

The library function

Here are the functions defined in the header file signal.h:

Serial number	Function & Description
1	void (signal(int sig, void (func)(int)))(int) This function sets a function to process the signal, that is, the signal processing program.
2	int raise(int sig) This function will cause the generated signal sig .SIG parameters are compatible with SIG macro.