bsd_signal(3) Linux Man Page

Name

bsd_signal - signal handling with BSD semantics

Library

Standard C library ( libc ", " -lc )

Synopsis

#include <signal.h> 
typedef void (*sighandler_t)(int); 
sighandler_t bsd_signal(int " signum ", sighandler_t  handler );

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

bsd_signal()

    Since glibc 2.26:
        _XOPEN_SOURCE >= 500
            && ! (_POSIX_C_SOURCE >= 200809L)
    glibc 2.25 and earlier:
        _XOPEN_SOURCE

Description

The bsd_signal() function takes the same arguments, and performs the same task, as signal(2).

The difference between the two is that bsd_signal() is guaranteed to provide reliable signal semantics, that is: a) the disposition of the signal is not reset to the default when the handler is invoked; b) delivery of further instances of the signal is blocked while the signal handler is executing; and c) if the handler interrupts a blocking system call, then the system call is automatically restarted. A portable application cannot rely on signal(2) to provide these guarantees.

Return Value

The bsd_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). allbox; lbx lb lb T{ bsd_signal()

Interface	Attribute	Value
T}	Thread safety	MT-Safe

Versions

Use of bsd_signal() should be avoided; use sigaction(2) instead.

On modern Linux systems, bsd_signal() and signal(2) are equivalent. But on older systems, signal(2) provided unreliable 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.

History

4.2BSD, POSIX.1-2001. Removed in POSIX.1-2008, recommending the use of sigaction(2) instead.

System Grab Bag