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Annotated edit history of signal(7) version 4, including all changes. View license author blame.
Rev Author # Line
1 perry 1 !!NAME
2
3
4 signal - list of available signals
5 !!DESCRIPTION
6
7
8 Linux supports the signals listed below. Several signal
9 numbers are architecture dependent. First the signals
10 described in POSIX.1.
4 CraigBox 11 <pre>
2 JohnMcPherson 12 Signal Value Action Comment
13 -------------------------------------------------------------------------
3 WyattEpp 14 SIGHUP 1 A Hangup detected on controlling terminal or
15 death of controlling process
2 JohnMcPherson 16 SIGINT 2 A Interrupt from keyboard
17 SIGQUIT 3 C Quit from keyboard
18 SIGILL 4 C Illegal Instruction
19 SIGABRT 6 C Abort signal from abort(3)
20 SIGFPE 8 C Floating point exception
21 SIGKILL 9 AEF Kill signal
22 SIGSEGV 11 C Invalid memory reference
23 SIGPIPE 13 A Broken pipe: write to pipe with no readers
24 SIGALRM 14 A Timer signal from alarm(2)
25 SIGTERM 15 A Termination signal
26 SIGUSR1 30,10,16 A User-defined signal 1
27 SIGUSR2 31,12,17 A User-defined signal 2
28 SIGCHLD 20,17,18 B Child stopped or terminated
29 SIGCONT 19,18,25 Continue if stopped
30 SIGSTOP 17,19,23 DEF Stop process
31 SIGTSTP 18,20,24 D Stop typed at tty
32 SIGTTIN 21,21,26 D tty input for background process
33 SIGTTOU 22,22,27 D tty output for background process
4 CraigBox 34 </pre>
1 perry 35 Next the signals not in POSIX.1 but described in SUSv2.
4 CraigBox 36 <pre>
2 JohnMcPherson 37 Signal Value Action Comment
38 -------------------------------------------------------------------------
39 SIGBUS 10,7,10 C Bus error (bad memory access)
40 SIGPOLL A Pollable event (Sys V). Synonym of SIGIO
41 SIGPROF 27,27,29 A Profiling timer expired
42 SIGSYS 12,-,12 C Bad argument to routine (SVID)
43 SIGTRAP 5 C Trace/breakpoint trap
44 SIGURG 16,23,21 B Urgent condition on socket (4.2 BSD)
45 SIGVTALRM 26,26,28 A Virtual alarm clock (4.2 BSD)
46 SIGXCPU 24,24,30 C CPU time limit exceeded (4.2 BSD)
47 SIGXFSZ 25,25,31 C File size limit exceeded (4.2 BSD)
4 CraigBox 48 </pre>
1 perry 49
3 WyattEpp 50 (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).)
1 perry 51
52
53 Next various other signals.
4 CraigBox 54
55 <pre>
2 JohnMcPherson 56 Signal Value Action Comment
57 --------------------------------------------------------------------
58 SIGIOT 6 C IOT trap. A synonym for SIGABRT
59 SIGEMT 7,-,7
60 SIGSTKFLT -,16,- A Stack fault on coprocessor
61 SIGIO 23,29,22 A I/O now possible (4.2 BSD)
1 perry 62
2 JohnMcPherson 63 SIGCLD -,-,18 A synonym for SIGCHLD
64 SIGPWR 29,30,19 A Power failure (System V)
65 SIGINFO 29,-,- A synonym for SIGPWR
66 SIGLOST -,-,- A File lock lost
67 SIGWINCH 28,28,20 B Window resize signal (4.3 BSD, Sun)
68 SIGUNUSED -,31,- A Unused signal (will be SIGSYS)
4 CraigBox 69 </pre>
70
1 perry 71
3 WyattEpp 72 (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.)
1 perry 73
74
2 JohnMcPherson 75 The letters in the "Action" column have the following meanings:
1 perry 76
4 CraigBox 77 ;A :Default action is to terminate the process.
1 perry 78
4 CraigBox 79 ;B :Default action is to ignore the signal.
1 perry 80
4 CraigBox 81 ;C :Default action is to terminate the process and dump core.
1 perry 82
4 CraigBox 83 ;D :Default action is to stop the process.
1 perry 84
4 CraigBox 85 ;E :Signal cannot be caught.
1 perry 86
4 CraigBox 87 ;F :Signal cannot be ignored.
1 perry 88
89 !!CONFORMING TO
2 JohnMcPherson 90 POSIX.1
1 perry 91
92 !!BUGS
4 CraigBox 93 __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__.
1 perry 94
4 CraigBox 95 !!SEE ALSO
1 perry 96
4 CraigBox 97 kill(1), kill(2), setitimer(2)
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