sysv_signal(3) Library Functions Manual sysv_signal(3)

sysv_signal - signal handling with System V semantics

Standard C library (libc, -lc)

#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);

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 semantics, 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.

The sysv_signal() function returns the previous value of the signal handler, or SIG_ERR on error.

As for signal(2).

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

Interface Attribute Value
sysv_signal () Thread safety MT-Safe

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.


sigaction(2), signal(2), bsd_signal(3), signal(7)

2024-05-02 Linux man-pages 6.9.1