The signal() function is a part of the signal.h library in C programming language. It is used to handle signals, which are software interrupts that can be sent to a running process by the operating system or by another process.

The function signature of signal() is as follows:

void (*signal(int sig, void (*func)(int)))(int);

The signal() function takes two arguments:

• sig: An integer that specifies the signal to be handled.
• func: A pointer to a function that specifies the action to be taken when the signal is received.

The return type of signal() is a pointer to a function that takes an integer argument and returns void. This pointer represents the previous signal handler associated with the specified signal.

Here's a brief explanation of the arguments and return value of signal():

• sig: The sig argument is an integer that specifies the signal to be handled. The signal number is an integer that corresponds to a particular signal. For example, SIGINT is the signal that is sent to a process when the user presses Ctrl-C. The signal number for SIGINT is usually 2.

• func: The func argument is a pointer to a function that specifies the action to be taken when the signal is received. This function is called a signal handler. The signal handler takes one integer argument, which is the signal number that triggered the signal. The function can perform any necessary actions in response to the signal, such as cleaning up resources or terminating the program.

• The return value of signal() is a pointer to the previous signal handler associated with the specified signal. This allows a program to chain multiple signal handlers together, so that each one is executed in turn when the signal is received.

It's important to note that the behavior of signal() is implementation-dependent, and its use is generally considered to be non-portable. The newer sigaction() function is often preferred for signal handling in modern C programming.