SIGNAL(7)

NAME
signal - list of available signals

DESCRIPTION
Linux supports the signals listed below. Several signal numbers are architecture dependent. First the signals described in POSIX.1.

Signal | Value | Action | Comment
SIGHUP | 1 | A | Hangup detected on controlling terminal
 |  |  | or death of controlling process
SIGINT | 2 | A | Interrupt from keyboard
SIGQUIT | 3 | A | Quit from keyboard
SIGILL | 4 | A | Illegal Instruction
SIGABRT | 6 | C | Abort signal from abort(3)
SIGFPE | 8 | C | Floating point exception
SIGKILL | 9 | AEF | Kill signal
SIGSEGV | 11 | C | Invalid memory reference
SIGPIPE | 13 | A | Broken pipe: write to pipe with no readers
SIGALRM | 14 | A | Timer signal from alarm(1)
SIGTERM | 15 | A | Termination signal
SIGUSR1 | 30,10,16 | A | User-defined signal 1
SIGUSR2 | 31,12,17 | A | User-defined signal 2
SIGCHLD | 20,17,18 | B | Child stopped or terminated
SIGCONT | 19,18,25 |  | Continue if stopped
SIGSTOP | 17,19,23 | DEF | Stop process
SIGTSTP | 18,20,24 | D | Stop typed at tty
SIGTTIN | 21,21,26 | D | tty input for background process
SIGTTOU | 22,22,27 | D | tty output for background process
Next various other signals.

Signal | Value | Action | Comment
SIGTRAP | 5 | CG | Trace/breakpoint trap
SIGIOT | 6 | CG | IOT trap. A synonym for SIGABRT
SIGEMT | 7,-,7 | G
SIGBUS | 10,7,10 | AG | Bus error
SIGSYS | 12,-,12 | G | Bad argument to routine (SVID)
SIGSTKFLT | -,16,- | AG | Stack fault on coprocessor
SIGURG | 16,23,21 | BG | Urgent condition on socket (4.2 BSD)
SIGIO | 23,29,22 | AG | I/O now possible (4.2 BSD)
SIGPOLL |  | AG | A synonym for SIGIO (System V)
SIGCLD | -,-,18 | G | A synonym for SIGCHLD
SIGXCPU | 24,24,30 | AG | CPU time limit exceeded (4.2 BSD)
SIGXFSZ | 25,25,31 | AG | File size limit exceeded (4.2 BSD)
SIGVTALRM | 26,26,28 | AG | Virtual alarm clock (4.2 BSD)
SIGPROF | 27,27,29 | AG | Profile alarm clock
SIGPWR | 29,30,19 | AG | Power failure (System V)
SIGINFO | 29,-,- | G | A synonym for SIGPWR
SIGLOST | -,-,- | AG | File lock lost
SIGWINCH | 28,28,20 | BG | Window resize signal (4.3 BSD, Sun)
SIGUNUSED | -,31,- | AG | Unused signal
(Here - denotes that a signal is absent; there where three values are given, the first one is usually valid for alpha and sparc, the middle one for i386 and ppc, the last one for mips. Signal 29 is SIGINFO / SIGPWR on an alpha but SIGLOST on a sparc.)

The letters in the "Action" column have the following meanings:

A   Default action is to terminate the process.

B   Default action is to ignore the signal.

C   Default action is to dump core.

D   Default action is to stop the process.

E   Signal cannot be caught.

F   Signal cannot be ignored.

G   Not a POSIX.1 conformant signal.

CONFORMING TO
POSIX.1

BUGS
SIGIO and SIGLOST have the same value. The latter is commented out in the kernel source, but the build process of some software still thinks that signal 29 is SIGLOST.

SEE ALSO
kill(1), kill(2), setitimer(2).