On POSIX

POSIX

POSIX , an acronym for "Portable Operating System Interface", is a family of standards specified by the IEEE for maintaining compatibility between operating systems...

-compliant platforms, SIGABRT is the signal

Signal (computing)

A signal is a limited form of inter-process communication used in Unix, Unix-like, and other POSIX-compliant operating systems. Essentially it is an asynchronous notification sent to a process in order to notify it of an event that occurred. When a signal is sent to a process, the operating system...

 sent to a process to tell it
to abort, i.e., to terminate. In source code

Source code

In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...

, SIGABRT is a symbolic constant

C preprocessor

The C preprocessor is the preprocessor for the C and C++ computer programming languages. The preprocessor handles directives for source file inclusion , macro definitions , and conditional inclusion ....

 defined in the header file

Header file

Some programming languages use header files. These files allow programmers to separate certain elements of a program's source code into reusable files. Header files commonly contain forward declarations of classes, subroutines, variables, and other identifiers...

 signal.h

Signal.h

signal.h is a header file defined in the C Standard Library to specify how a program handles signals while it executes. A signal can report some exceptional behavior within the program , or a signal can report some asynchronous event outside the program .A signal can be generated...

. Symbolic signal names are used because signal numbers can vary across platforms.

On some platforms such as Linux

Linux

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

, HP-UX

HP-UX

HP-UX is Hewlett-Packard's proprietary implementation of the Unix operating system, based on UNIX System V and first released in 1984...

 and AIX, SIGIOT is a synonym for SIGABRT.

On Linux

Linux

Linux is a Unix-like computer operating system assembled under the model of free and open source software development and distribution. The defining component of any Linux system is the Linux kernel, an operating system kernel first released October 5, 1991 by Linus Torvalds...

, HP-UX

HP-UX

HP-UX is Hewlett-Packard's proprietary implementation of the Unix operating system, based on UNIX System V and first released in 1984...

 and Solaris SIGABRT is signal number 6.

Etymology

SIG is a common prefix for signal names. ABRT is an abbreviation for abort.

Usage

SIGABRT is sent by the process to itself when it calls the abort libc function, defined in stdlib.h. The SIGABRT signal can be caught, but it cannot be blocked; if the signal handler returns then all open streams are closed and flushed and the program terminates (dumping core

Core dump

In computing, a core dump consists of the recorded state of the working memory of a computer program at a specific time, generally when the program has terminated abnormally...

 if appropriate). This means that the abort call never returns. Because of this characteristic, it is often used to signal fatal conditions in support libraries, situations where the current operation cannot be completed but the main program can perform cleanup before exiting. It is used when an assertion

Assertion (computing)

In computer programming, an assertion is a predicate placed in a program to indicate that the developer thinks that the predicate is always true at that place.For example, the following code contains two assertions:...

fails.