Signal handling in Linux using signal() call

signal() function in linux is used to sets of handler for the given signal number, the handler is any of SIG_DFL(default action) or SIG_IGN(ignore signal) or address of user defined function which we called signal handler

syntax:

         sighandler_t signal(int signum, sighandler_t handler);

the second parameter is the address of the signal handler function (function pointer), which has the following syntax

         typedef void (*sighandler_t)(int );

Here the parameter int represents the Signal number.

Here is the simple C program which describes the SIGINT Signal handling in linux

signal.c

#include<stdio.h>

#include<signal.h>

void sig_handler(int signum)

{

    printf("I'm in INT_SIGNAL handler:%d\n",signum);

}

int main()

{

    signal(SIGINT,sig_handler);

    while(1)

    {

        printf("hello i'm in main\n");

        sleep(1);

    }

    return 0;

}

Output:

$gcc -o signal signal.c

$./signal

hello i'm in main

hello i'm in main

^CI'm in INT_SIGNAL handler:2

hello i'm in main

hello i'm in main

hello i'm in main

^CI'm in INT_SIGNAL handler:2

hello i'm in main

hello i'm in main

^Z

[2]+ Stopped ./signal

Note: to send the SIGINT signal to the process, use shortcut key CTRL+c in the keyboard while program being executed, then our handler will invoked. To stop the program press CTRL+z keys.

Note: to see list of signals in linux system open terminal, then enter the command

               $kill -l