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 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 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. 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 attributes(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 6.9.1 2024-05-02 sysv_signal(3)