The "signal.h" header file in C programming provides a way to handle signals, which are asynchronous notifications sent to a process by the operating system or another process.

The "signal.h" header file defines several functions and constants for handling signals, including:

1. "signal": Sets the action to be taken when a signal is received.

2. "raise": Sends a signal to the current process.

3. Constants for different types of signals, such as "SIGINT" for the interrupt signal and "SIGSEGV" for the segmentation fault signal.

4. A signal handler function type "typedef void (*sighandler_t)(int)" which is used to define the signature of the signal handling functions.

Here is an example of using the "signal.h" header file in a C program:

#include <stdio.h>
#include <signal.h>

void signal_handler(int sig) {
    printf("Received signal %d\n", sig);
}

int main() {
    signal(SIGINT, signal_handler);

    printf("Running...\n");

    raise(SIGINT);

    printf("Done.\n");

    return 0;
}

In this example, the "signal.h" header file functions are used to set up a signal handler function for the interrupt signal (SIGINT) and raise a signal using the "raise" function. When the interrupt signal is raised, the "signal_handler" function is called, which prints a message indicating that the signal was received. The output of the program will be:

Running...
Received signal 2
Done.

Note that the behavior of signals is implementation-dependent and can have security implications, so they should be used with caution.