C Language: signal function
(Install Signal Handler)
In the C Programming Language, the signal function installs a function as the handler for a signal.
Syntax
The syntax for the signal function in the C Language is:
void (*signal(int sig, void (*func)(int)))(int);
Parameters or Arguments
- sig
- The numeric value of the signal.
- func
- The function to install as the signal handler.
Returns
The signal function returns a pointer to the previous handler for this signal. If the handler can not be installed, the signal function returns SIG_ERR.
Required Header
In the C Language, the required header for the signal function is:
#include <signal.h>
Applies To
In the C Language, the signal function can be used in the following versions:
- ANSI/ISO 9899-1990
signal Example
/* Example using signal by TechOnTheNet.com */
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
void signal_handler(int signal)
{
/* Display a message indicating we have received a signal */
if (signal == SIGUSR2) printf("Received a SIGUSR2 signal\n");
/* Exit the application */
exit(0);
}
int main(int argc, const char * argv[])
{
/* Display a message indicating we are registering the signal handler */
printf("Registering the signal handler\n");
/* Register the signal handler */
signal(SIGUSR2, signal_handler);
/* Display a message indicating we are raising a signal */
printf("Raising a SIGUSR2 signal\n");
/* Raise the SIGUSR2 signal */
raise(SIGUSR2);
/* Display a message indicating we are leaving main */
printf("Finished main\n");
return 0;
}
When compiled and run, this application will output:
Registering the signal handler Raising a SIGUSR2 signal Received a SIGUSR2 signal
See Also
Other C functions that are noteworthy when dealing with the signal function:
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