struct	sigaction {
	void	(*	sa_handler)(int);
	void	(*	sa_sigaction)(int, siginfo_t *, void *);
	sigset_t		sa_mask;
	int		sa_flags;
	void	(*	sa_restorer)(void);
};

SA_NOCLDSTOP

If signum is SIGCHLD, do not receive notification when child processes stop (i.e., when they receive one of SIGSTOP, SIGTSTP, SIGTTIN or SIGTTOU) or resume (i.e., they receive SIGCONT) (see wait(2)). This flag is only meaningful when establishing a handler for SIGCHLD.

SA_NOCLDWAIT (since Linux 2.6)

If signum is SIGCHLD, do not transform children into zombies when they terminate. See also waitpid(2). This flag is only meaningful when establishing a handler for SIGCHLD, or when setting that signal's disposition to SIG_DFL.

If the SA_NOCLDWAIT flag is set when establishing a handler for SIGCHLD, POSIX.1 leaves it unspecified whether a SIGCHLD signal is generated when a child process terminates. On Linux, a SIGCHLD signal is generated in this case; on some other implementations, it is not.

SA_NODEFER

Do not prevent the signal from being received from within its own signal handler. This flag is only meaningful when establishing a signal handler. SA_NOMASK is an obsolete, nonstandard synonym for this flag.

SA_ONSTACK

Call the signal handler on an alternate signal stack provided by sigaltstack(2). If an alternate stack is not available, the default stack will be used. This flag is only meaningful when establishing a signal handler.

SA_RESETHAND

Restore the signal action to the default state once the signal handler has been called. This flag is only meaningful when establishing a signal handler. SA_ONESHOT is an obsolete, nonstandard synonym for this flag.

SA_RESTART

Provide behavior compatible with BSD signal semantics by making certain system calls restartable across signals. This flag is only meaningful when establishing a signal handler. See signal(7) for a discussion of system call restarting.

SA_SIGINFO (since Linux 2.2)

The signal handler takes 3 arguments, not one. In this case, sa_sigaction should be set instead of sa_handler. This flag is only meaningful when establishing a signal handler.

siginfo_t {
    int      si_signo;    /* Signal number */
    int      si_errno;    /* An errno value */
    int      si_code;     /* Signal code */
    int      si_trapno;   /* Trap number that caused
                             hardware-generated signal
                             (unused on most architectures) */
    pid_t    si_pid;      /* Sending process ID */
    uid_t    si_uid;      /* Real user ID of sending process */
    int      si_status;   /* Exit value or signal */
    clock_t  si_utime;    /* User time consumed */
    clock_t  si_stime;    /* System time consumed */
    sigval_t si_value;    /* Signal value */
    int      si_int;      /* POSIX.1b signal */
    void    *si_ptr;      /* POSIX.1b signal */
    int      si_overrun;  /* Timer overrun count; POSIX.1b timers */
    int      si_timerid;  /* Timer ID; POSIX.1b timers */
    void    *si_addr;     /* Memory location which caused fault */
    long     si_band;     /* Band event (was int in
                             glibc 2.3.2 and earlier) */
    int      si_fd;       /* File descriptor */
    short    si_addr_lsb; /* Least significant bit of address
                             (since kernel 2.6.32) */
}

SI_USER

kill(2) or raise(3)

SI_KERNEL

Sent by the kernel.

SI_QUEUE

sigqueue(3)

SI_TIMER

POSIX timer expired

SI_MESGQ

POSIX message queue state changed (since Linux 2.6.6); see mq_notify(3)

SI_ASYNCIO

AIO completed

SI_SIGIO

queued SIGIO

SI_TKILL

tkill(2) or tgkill(2) (since Linux 2.4.19)

ILL_ILLOPC

illegal opcode

ILL_ILLOPN

illegal operand

ILL_ILLADR

illegal addressing mode

ILL_ILLTRP

illegal trap

ILL_PRVOPC

privileged opcode

ILL_PRVREG

privileged register

ILL_COPROC

coprocessor error

ILL_BADSTK

internal stack error

FPE_INTDIV

integer divide by zero

FPE_INTOVF

integer overflow

FPE_FLTDIV

floating-point divide by zero

FPE_FLTOVF

floating-point overflow

FPE_FLTUND

floating-point underflow

FPE_FLTRES

floating-point inexact result

FPE_FLTINV

floating-point invalid operation

FPE_FLTSUB

subscript out of range

SEGV_MAPERR

address not mapped to object

SEGV_ACCERR

invalid permissions for mapped object

BUS_ADRALN

invalid address alignment

BUS_ADRERR

nonexistent physical address

BUS_OBJERR

object-specific hardware error

BUS_MCEERR_AR (since Linux 2.6.32)

Hardware memory error consumed on a machine check; action required.

BUS_MCEERR_AO (since Linux 2.6.32)

Hardware memory error detected in process but not consumed; action optional.

TRAP_BRKPT

process breakpoint

TRAP_TRACE

process trace trap

TRAP_BRANCH (since Linux 2.4)

process taken branch trap

TRAP_HWBKPT (since Linux 2.4)

hardware breakpoint/watchpoint

CLD_EXITED

child has exited

CLD_KILLED

child was killed

CLD_DUMPED

child terminated abnormally

CLD_TRAPPED

traced child has trapped

CLD_STOPPED

child has stopped

CLD_CONTINUED

stopped child has continued (since Linux 2.6.9)

POLL_IN

data input available

POLL_OUT

output buffers available

POLL_MSG

input message available

POLL_ERR

I/O error

POLL_PRI

high priority input available

POLL_HUP

device disconnected