ISO-compliant implementation of signals supported by the signal() function in the C library and additional type arguments

Table 11 shows the signals supported by the signal() function. It also shows which signals use an additional argument to give more information about the circumstance in which the signal was raised. The additional argument is given in the type parameter of __raise(). For example, division by floating-point zero results in a SIGFPE signal with a corresponding additional argument of FE_EX_DIVBYZERO.

Although SIGSTAK exists in signal.h, this signal is not generated by the C library and is considered obsolete.

A signal number greater than SIGUSR2 can be passed through __raise() and caught by the default signal handler, but it cannot be caught by a handler registered using signal().

signal() returns an error code if you try to register a handler for a signal number greater than SIGUSR2.

The default handling of all recognized signals is to print a diagnostic message and call exit(). This default behavior applies at program startup and until you change it.

For all the signals in Table 11, when a signal occurs, if the handler points to a function, the equivalent of signal(sig, SIG_DFL) is executed before the call to the handler.

If the SIGILL signal is received by a handler specified to by the signal() function, the default handling is reset.