BSD_SIGNAL(3) Linux Programmer s Manual BSD_SIGNAL(3)

NAME bsd_signal - signal handling with BSD semantics

SYNOPSIS #define _XOPEN_SOURCE #include <signal.h>

typedef void (*sighandler_t)(int);

sighandler_t bsd_signal(int signum, sighandler_t handler);

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 sys- tem 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 han- dler, or SIG_ERR on error.

ERRORS As for signal(2).

CONFORMING TO 4.2BSD, POSIX.1-2001. POSIX.1-2008 removes the specification of bsd_signal(), recommending the use of sigaction(2) instead.

NOTES 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 only defined if the _GNU_SOURCE feature test macro is defined.

SEE ALSO sigaction(2), signal(2), sysv_signal(3), feature_test_macros(7), sig- nal(7)

COLOPHON This page is part of release 3.22 of the Linux man-pages project. A description of the project, and information about reporting bugs, can be found at

2009-03-15 BSD_SIGNAL(3)