IPC Signals

IPC Signals
C Standard Signals
UNIX POSIX/SUS Standard Signals

Signals are generally used in UNIX-like systems for performing IPC actions.

C Standard Signals

SIGABRT (Abort)
SIGFPE (Floating point exception)
SIGILL (Illegal instruction)
SIGINT (Interrupt)
SIGSEGV (Segmentation violation, due to invalid memory access)
SIGTERM (Terminate a program)

UNIX POSIX/SUS Standard Signals

Note

Different signals are defined for software to use them in the way they want, but if they don't make use of them, they fall back to the default action
Signal numbers are usually left to implementations, but POSIX standard defines numbers for a few signals

Signal	Signal Number	Default Action	Description
SIGABRT	6	Terminate (core dump)	Process abort signal
SIGALRM	14	Terminate	Alarm clock
SIGBUS	—	Terminate (core dump)	Access to an undefined portion of a memory object
SIGCHLD	—	Ignore	Child process terminated, stopped, or continued
SIGCONT	—	Continue	Continue executing, if stopped
SIGFPE	8	Terminate (core dump)	Erroneous arithmetic operation
SIGHUP	1	Terminate	Hangup
SIGILL	4	Terminate (core dump)	Illegal instruction
SIGINT	2	Terminate	Terminal interrupt signal
SIGKILL	9	Terminate	Kill (cannot be caught or ignored)
SIGPIPE	13	Terminate	Write on a pipe with no one to read it
SIGPOLL	—	Terminate	Pollable event
SIGPROF	—	Terminate	Profiling timer expired
SIGQUIT	3	Terminate (core dump)	Terminal quit signal
SIGSEGV	11	Terminate (core dump)	Invalid memory reference
SIGSTOP	—	Stop	Stop executing (cannot be caught or ignored)
SIGSYS	—	Terminate (core dump)	Bad system call
SIGTERM	15	Terminate	Termination signal
SIGTRAP	5	Terminate (core dump)	Trace/breakpoint trap
SIGTSTP	—	Stop	Terminal stop signal
SIGTTIN	—	Stop	Background process attempting read
SIGTTOU	—	Stop	Background process attempting write
SIGUSR1	—	Terminate	User-defined signal 1
SIGUSR2	—	Terminate	User-defined signal 2
SIGURG	—	Ignore	Out-of-band data is available at a socket
SIGVTALRM	—	Terminate	Virtual timer expired
SIGXCPU	—	Terminate (core dump)	CPU time limit exceeded
SIGXFSZ	—	Terminate (core dump)	File size limit exceeded
SIGWINCH	—	Ignore	Terminal window size changed
# Miscellaneous Signals
These signals aren't defined by POSIX, but are used in some systems.

SIGEMT
SIGINFO
SIGPWR
SIGLOST
SIGSTKFLT
SIGUNUSED
SIGCLD