Question

I am working on an assignment where I am implementing the unix history command in a shell. In my program I have written a signal handler for SIGINT. When a user enters (ctrl)(c) their history is displayed.

When my program terminates I need to store the history in a file. Is there an easy way to detect when my program has exited? Or do I need to have a signal handler for every type of signal ((ctrl)(d), pausebreak, etc).

Answer 1

atexit() is probably what you’re looking for, see the manual page: man 3 atexit

Usage is something like:

#include <stdlib.h>

static void save_the_file(void)
{
    /* ... */
}

int main()
{
    atexit(save_the_file);
    return 0;
}

Another option is to use the destructor attribute (GCC/Clang):

static __attribute__((destructor)) void save_the_file(void)
{
     /* your code */
}