LinuxLOCALRuns in your browser

Unix Signals Reference

Searchable reference of standard Linux signals with default actions, catchability, and exit status codes.

This tool handles input and primary processing in your browser and is designed not to send the input to QuickKit’s server.

Filter the tableType a number, signal name, or keyword from the note

Signal / exit status lookup

Signal number (1-31, 34-64)

Unix signals reference table

Number	Signal name	Default action	Catchable	Exit status	Note
1	SIGHUP	Terminate	Yes	129	Terminal hangup, or controlling process died. Widely reused to mean 'reload configuration', by convention only.
2	SIGINT	Terminate	Yes	130	Interrupt from keyboard (Ctrl-C).
3	SIGQUIT	Terminate + core dump	Yes	131	Quit from keyboard (Ctrl-\).
4	SIGILL	Terminate + core dump	Yes	132	Illegal instruction.
5	SIGTRAP	Terminate + core dump	Yes	133	Trace or breakpoint trap.
6	SIGABRT	Terminate + core dump	Yes	134	Abort, as raised by abort(3). SIGIOT is the same number.
7	SIGBUS	Terminate + core dump	Yes	135	Bus error (bad memory access).
8	SIGFPE	Terminate + core dump	Yes	136	Arithmetic exception, despite the name not only floating point.
9	SIGKILL	Terminate	No	137	Kill. Cannot be caught, blocked, or ignored.
10	SIGUSR1	Terminate	Yes	138	User-defined signal 1.
11	SIGSEGV	Terminate + core dump	Yes	139	Invalid memory reference.
12	SIGUSR2	Terminate	Yes	140	User-defined signal 2.
13	SIGPIPE	Terminate	Yes	141	Write to a pipe with no reader.
14	SIGALRM	Terminate	Yes	142	Timer signal from alarm(2).
15	SIGTERM	Terminate	Yes	143	Termination request. The default signal sent by kill(1).
16	SIGSTKFLT	Terminate	Yes	144	Stack fault on a coprocessor. Linux-specific and unused.
17	SIGCHLD	Ignore	Yes	145	Child stopped or terminated.
18	SIGCONT	Continue	Yes	146	Continue if stopped.
19	SIGSTOP	Stop	No	147	Stop process. Cannot be caught, blocked, or ignored.
20	SIGTSTP	Stop	Yes	148	Stop typed at the terminal (Ctrl-Z).
21	SIGTTIN	Stop	Yes	149	Background process attempted to read from the terminal.
22	SIGTTOU	Stop	Yes	150	Background process attempted to write to the terminal.
23	SIGURG	Ignore	Yes	151	Urgent condition on a socket.
24	SIGXCPU	Terminate + core dump	Yes	152	CPU time limit exceeded.
25	SIGXFSZ	Terminate + core dump	Yes	153	File size limit exceeded.
26	SIGVTALRM	Terminate	Yes	154	Virtual alarm clock.
27	SIGPROF	Terminate	Yes	155	Profiling timer expired.
28	SIGWINCH	Ignore	Yes	156	Terminal window size changed.
29	SIGIO	Terminate	Yes	157	I/O now possible. SIGPOLL is the same number.
30	SIGPWR	Terminate	Yes	158	Power failure.
31	SIGSYS	Terminate + core dump	Yes	159	Bad system call. SIGUNUSED is the same number.

How it works

A reference of standard Linux signals (1-31, and real-time signals 34-64) with their default actions, whether they can be caught or blocked, and the exit status a process receives when killed by each signal. These signal numbers follow the Linux asm-generic definitions used on x86-64, ARM, and most architectures; Alpha, SPARC, MIPS, and PA-RISC assign several signals different numbers. Use `kill -l` on your target machine to verify. The SIGHUP meaning of "reload configuration" is a convention individual daemons chose, not a kernel definition. Exit-status lookup accepts values 129-192 and reports the corresponding signal; the formula 128 + signal number is a bash/shell convention and not a kernel value, so an ordinary program is free to exit with 137 for any reason.

Signal / exit status lookup

Unix signals reference table

Related tools

ICMP & ICMPv6 Type/Code Reference

IP Protocol Numbers

Well-Known Port Reference