@aescling Yep! They have the example that a text editor, if interrupted while doing a long printout (who of us hasn't accidentally cat-ed a huge file and then regretted it...), shouldn't exit, but should jump back to the main loop (without losing the work). Page 227, this is the code:

#include <signal.h>
#include <setjmp.h>
jmp_buf sjbuf;

main()
{
    int onintr();

    if (signal(SIGINT, SIG_IGN) != SIG_IGN)
        signal(SIGINT, onintr);
    setjmp(sjbuf); /* save current stack position */

    for (;;) {
        /* main processing loop */
    }
    ...
}

onintr()    /* reset if interrupted */
{
    signal(SIGINT, onintr); /* reset for next interrupt */
    printf("\nInterrupt\n");
    longjmp(sjbuf, 0);        /* return to saved state */
}

It makes sense to me! How would you solve this without setjmp() / longjmp()?

@aescling I really liked that book, it made me better at shell programming and at UNIX in general