Understanding the Linux Kernel, Chapter 11 Signals, Daniel P. Bovet & Marco Cesati, 3rd Edition, O'Reilly
man 7 signal (Linux manual page)
Standard signals
"P1990" : POSIX.1-1990 standard
"P2001" : the signal was added in SUSv2 and POSIX.1-2001.
NOTE: Numbers for X86/ARM and most others;
For {Alpha/SPARC, MIPS, PARISC} they would be different)
────────────────────────────────────────────────────────────────────────
Signal Standard Action Comment
────────────────────────────────────────────────────────────────────────
1 SIGHUP P1990 Term Hangup detected on controlling terminal
or death of controlling process
2 SIGINT P1990 Term Interrupt from keyboard
3 SIGQUIT P1990 Core Quit from keyboard
4 SIGILL P1990 Core Illegal Instruction
5 SIGTRAP P2001 Core Trace/breakpoint trap
6 SIGABRT P1990 Core Abort signal from abort(3)
6 SIGIOT - Core IOT trap. A synonym for SIGABRT
7 SIGBUS P2001 Core Bus error (bad memory access)
8 SIGFPE P1990 Core Floating-point exception
9 SIGKILL P1990 Term Kill signal
10 SIGUSR1 P1990 Term User-defined signal 1
11 SIGSEGV P1990 Core Invalid memory reference
12 SIGUSR2 P1990 Term User-defined signal 2
13 SIGPIPE P1990 Term Broken pipe: write to pipe with no
14 SIGALRM P1990 Term Timer signal from alarm(2)
15 SIGTERM P1990 Term Termination signal
16 SIGSTKFLT - Term Stack fault on coprocessor (unused)
16 UNUSED ----- ---- (in some cases..)
17 SIGCHLD P1990 Ign Child stopped or terminated
SIGCLD - Ign A synonym for SIGCHLD
18 SIGCONT P1990 Cont Continue if stopped
19 SIGSTOP P1990 Stop Stop process
20 SIGTSTP P1990 Stop Stop typed at terminal
21 SIGTTIN P1990 Stop Terminal input for background process
22 SIGTTOU P1990 Stop Terminal output for background process
23 SIGURG P2001 Ign Urgent condition on socket (4.2BSD)
24 SIGXCPU P2001 Core CPU time limit exceeded (4.2BSD);
25 SIGXFSZ P2001 Core File size limit exceeded (4.2BSD);
see setrlimit(2)
26 SIGVTALRM P2001 Term Virtual alarm clock (4.2BSD)
27 SIGPROF P2001 Term Profiling timer expired
28 SIGWINCH - Ign Window resize signal (4.3BSD, Sun)
29 SIGIO - Term I/O now possible (4.2BSD)
29 SIGPOLL P2001 Term Pollable event (Sys V);
synonym for SIGIO
30 SIGPWR - Term Power failure (System V)
30 SIGINFO - A synonym for SIGPWR
31 SIGSYS P2001 Core Bad system call (SVr4);
see also seccomp(2)
SIGUNUSED - Core Synonymous with SIGSYS
- SIGEMT - Term Emulator trap
SIGLOST - Term File lock lost (unused)
────────────────────────────────────────────────────────────────────────
The signals SIGKILL and SIGSTOP cannot be caught, blocked, or
ignored.
Up to and including Linux 2.2, the default behavior for SIGSYS,
SIGXCPU, SIGXFSZ, and (on architectures other than SPARC and
MIPS) SIGBUS was to terminate the process (without a core dump).
(On some other UNIX systems the default action for SIGXCPU and
SIGXFSZ is to terminate the process without a core dump.) Linux
2.4 conforms to the POSIX.1-2001 requirements for these signals,
terminating the process with a core dump.
SIGEMT is not specified in POSIX.1-2001, but nevertheless appears
on most other UNIX systems, where its default action is typically
to terminate the process with a core dump.
SIGPWR (which is not specified in POSIX.1-2001) is typically
ignored by default on those other UNIX systems where it appears.
SIGIO (which is not specified in POSIX.1-2001) is ignored by
default on several other UNIX systems.