Name	Number	Default action	Description
SIGHUP	1	Exit	Hangup (ref termio(7I)).
SIGINT	2	Exit	Interrupt (ref termio(7I)).
SIGQUIT	3	Core	Quit (ref termio(7I))
SIGILL	4	Core	Illegal Instruction
SIGTRAP	5	Core	Trace or breakpoint trap
SIGABRT	6	Core	Abort
SIGEMT	7	Core	Emulation trap
SIGFPE	8	Core	Arithmetic exception
SIGKILL	9	Exit	Kill
SIGBUS	10	Core	Bus error -- actually a misaligned address error
SIGSEGV	11	Core	Segmentation fault -- an address reference boundary error
SIGSYS	12	Core	Bad system call
SIGPIPE	13	Exit	Broken pipe
SIGALRM	14	Exit	Alarm clock
SIGTERM	15	Exit	Terminated
SIGUSR1	16	Exit	User defined signal 1
SIGUSR2	17	Exit	User defined signal 2
SIGCHLD	18	Ignore	Child process status changed
SIGPWR	19	Ignore	Power fail or restart
SIGWINCH	20	Ignore	Window size change
SIGURG	21	Ignore	Urgent socket condition
SIGPOLL	22	Exit	Pollable event (ref streamio(7I))
SIGSTOP	23	Stop	Stop (cannot be caught or ignored)
SIGTSTP	24	Stop	Stop (job control, e.g., ^z))
SIGCONT	25	Ignore	Continued
SIGTTIN	26	Stop	Stopped -- tty input (ref termio(7I))
SIGTTOU	27	Stop	Stopped -- tty output (ref termio(7I))
SIGVTALRM	28	Exit	Virtual timer expired
SIGPROF	29	Exit	Profiling timer expired
SIGXCPU	30	Core	CPU time limit exceeded (ref getrlimit(2))
SIGXFSZ	31	Core	File size limit exceeded (ref getrlimit(2))
SIGWAITING	32	Ignore	Concurrency signal used by threads library
SIGLWP	33	Ignore	Inter-LWP signal used by threads library
SIGFREEZE	34	Ignore	Checkpoint suspend
SIGTHAW	35	Ignore	Checkpoint resume
SIGCANCEL	36	Ignore	Cancellation signal used by threads library
SIGLOST	37	Ignore	Resource lost
SIGRTMIN	38	Exit	Highest priority realtime signal
SIGRTMAX	45	Exit	Lowest priority realtime signal

Figure 1. k_sigset_t data structure
(Click image to enlarge.)

Signals in Solaris

The multithreaded architecture of Solaris made for some interesting challenges in developing a means of supporting signals that comply with the UNIX signal semantics, as defined by industry standards such as POSIX. Signals traditionally go through two well-defined stages: generation and delivery. Signal generation is the point of origin of the signal, or the sending phase. A signal is said to be delivered when whatever disposition that has been established for the signal is invoked, even if it is to be ignored. If a signal is being blocked, thus postponing delivery, it is considered pending.

User threads in Solaris, created via explicit calls to either thr_create(3T) or pthread_create(3T), all have their own signal masks. Threads can choose to block signals independent of other threads executing in the same process, which allows different threads to take delivery of different signals at various times during process execution. The thread's libraries (POSIX and Solaris threads) provide thr_sigsetmask(3T) and pthread_sigmask(3T) interfaces for establishing per-user thread signal masks. The disposition and handlers for all signals are shared by all the threads in a process. So, for example, a SIGINT with the default disposition in place will cause the entire process to exit.