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Signal | Value | Action | Comment |
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 |
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 |
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: