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GSIGNAL

Section: Linux Programmer's Manual (3)
Updated: 2017-09-15
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NAME

gsignal, ssignal - software signal facility

SYNOPSIS

#include <signal.h>

typedef void (*sighandler_t)(int);

int gsignal(int signum);

sighandler_t ssignal(int signum, sighandler_t action);

Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

gsignal(), ssignal():
    Since glibc 2.19:
        _DEFAULT_SOURCE
    Glibc 2.19 and earlier:
        _SVID_SOURCE

DESCRIPTION

Don't use these functions under Linux. Due to a historical mistake, under Linux these functions are aliases for raise(3) and signal(2), respectively.

Elsewhere, on System V-like systems, these functions implement software signaling, entirely independent of the classical signal(2) and kill(2) functions. The function ssignal() defines the action to take when the software signal with number signum is raised using the function gsignal(), and returns the previous such action or SIG_DFL. The function gsignal() does the following: if no action (or the action SIG_DFL) was specified for signum, then it does nothing and returns 0. If the action SIG_IGN was specified for signum, then it does nothing and returns 1. Otherwise, it resets the action to SIG_DFL and calls the action function with argument signum, and returns the value returned by that function. The range of possible values signum varies (often 1-15 or 1-17).

ATTRIBUTES

For an explanation of the terms used in this section, see attributes(7).

Interface	Attribute	Value
gsignal()	Thread safety	MT-Safe
ssignal()	Thread safety	MT-Safe sigintr

CONFORMING TO

These functions are available under AIX, DG/UX, HP-UX, SCO, Solaris, Tru64. They are called obsolete under most of these systems, and are broken under Linux libc and glibc. Some systems also have gsignal_r() and ssignal_r().

COLOPHON

This page is part of release 4.13 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.