SIGUNUSED

SIGUNUSED (non-POSIX)
Description Unused signal
Default action Abnormal termination of the process
SA_SIGINFO macros

None

On some Unix-like platforms, SIGUNUSED is a signal that has no purpose at present but is intended for future use. The symbolic constant for SIGUNUSED is defined in the header file signal.h. Symbolic signal names are used because signal numbers can vary across platforms.

Etymology

SIG is a common prefix for signal names. UNUSED is the word unused.

Usage

In Linux 2.6 on the x86, PowerPC and SuperH architectures, signal 31 is designated for future use as SIGSYS; since SIGSYS is currently unimplemented, the signal number is temporarily assigned to SIGUNUSED instead.