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 | C | Quit from keyboard
SIGILL | 4 | C | 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(2)
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 the signals not in POSIX.1 but described in SUSv2.

Signal | Value | Action | Comment
SIGBUS | 10,7,10 | C | Bus error (bad memory access)
SIGPOLL |  | A | Pollable event (Sys V). Synonym of SIGIO
SIGPROF | 27,27,29 | A | Profiling timer expired
SIGSYS | 12,-,12 | C | Bad argument to routine (SVID)
SIGTRAP | 5 | C | Trace/breakpoint trap
SIGURG | 16,23,21 | B | Urgent condition on socket (4.2 BSD)
SIGVTALRM | 26,26,28 | A | Virtual alarm clock (4.2 BSD)
SIGXCPU | 24,24,30 | C | CPU time limit exceeded (4.2 BSD)
SIGXFSZ | 25,25,31 | C | File size limit exceeded (4.2 BSD)
(For the cases SIGSYS, SIGXCPU, SIGXFSZ, and on some architectures also SIGBUS, the Linux default action up to now (2.3.27) is A (terminate), while SUSv2 prescribes C (terminate and dump core).) Next various other signals.

Signal | Value | Action | Comment
SIGIOT | 6 | C | IOT trap. A synonym for SIGABRT
SIGEMT | 7,-,7 |
SIGSTKFLT | -,16,- | A | Stack fault on coprocessor
SIGIO | 23,29,22 | A | I/O now possible (4.2 BSD)
SIGCLD | -,-,18 |  | A synonym for SIGCHLD
SIGPWR | 29,30,19 | A | Power failure (System V)
SIGINFO | 29,-,- |  | A synonym for SIGPWR
SIGLOST | -,-,- | A | File lock lost
SIGWINCH | 28,28,20 | B | Window resize signal (4.3 BSD, Sun)
SIGUNUSED | -,31,- | A | Unused signal (will be SIGSYS)
(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 and sh, 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 terminate the process and dump core.

D   Default action is to stop the process.

E   Signal cannot be caught.

F   Signal cannot be ignored.

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)