gsignal, ssignal — software signal facility


#include <signal.h>

typedef void (*sighandler_t)(int);
int gsignal( int signum);
sighandler_t ssignal( int signum,
  sighandler_t action);
[Note] Note
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
gsignal(), ssignal():
Since glibc 2.19:
_DEFAULT_SOURCE Glibc 2.19 and earlier:


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).


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


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().


kill(2), signal(2), raise(3)


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