sysv_signal(3) Library Functions Manual sysv_signal(3)
NAME
sysv_signal - signal handling with System V semantics
LIBRARY
Standard C library (libc, -lc)
SYNOPSIS
#define _GNU_SOURCE /* See feature_test_macros(7) */
#include <signal.h>
typedef void (*sighandler_t)(int);
sighandler_t sysv_signal(int signum, sighandler_t handler);
DESCRIPTION
The sysv_signal() function takes the same arguments, and performs the
same task, as signal(2).
However sysv_signal() provides the System V unreliable signal seman-
tics, that is: a) the disposition of the signal is reset to the default
when the handler is invoked; b) delivery of further instances of the
signal is not blocked while the signal handler is executing; and c) if
the handler interrupts (certain) blocking system calls, then the system
call is not automatically restarted.
RETURN VALUE
The sysv_signal() function returns the previous value of the signal
handler, or SIG_ERR on error.
ERRORS
As for signal(2).
ATTRIBUTES
For an explanation of the terms used in this section, see attrib-
utes(7).
┌───────────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├───────────────────────────────────────────┼───────────────┼─────────┤
│ sysv_signal() │ Thread safety │ MT-Safe │
└───────────────────────────────────────────┴───────────────┴─────────┘
VERSIONS
Use of sysv_signal() should be avoided; use sigaction(2) instead.
On older Linux systems, sysv_signal() and signal(2) were equivalent.
But on newer systems, signal(2) provides reliable signal semantics; see
signal(2) for details.
The use of sighandler_t is a GNU extension; this type is defined only
if the _GNU_SOURCE feature test macro is defined.
STANDARDS
None.
SEE ALSO
sigaction(2), signal(2), bsd_signal(3), signal(7)
Linux man-pages 6.7 2023-10-31 sysv_signal(3)
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