sigpause (3) - Linux Manuals

sigpause: atomically release blocked signals and wait for interrupt

Command to display sigpause manual in Linux: $ man 3 sigpause

NAME

sigpause - atomically release blocked signals and wait for interrupt

SYNOPSIS

#include <signal.h>

int sigpause(int sigmask);  /* BSD (but see NOTES) */

int sigpause(int sig);      /* System V / UNIX 95 */

DESCRIPTION

Don't use this function. Use sigsuspend(2) instead.

The function sigpause() is designed to wait for some signal. It changes the process's signal mask (set of blocked signals), and then waits for a signal to arrive. Upon arrival of a signal, the original signal mask is restored.

RETURN VALUE

If sigpause() returns, it was interrupted by a signal and the return value is -1 with errno set to EINTR.

ATTRIBUTES

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

Interface	Attribute	Value
sigpause()	Thread safety	MT-Safe

CONFORMING TO

The System V version of sigpause() is standardized in POSIX.1-2001. It is also specified in POSIX.1-2008, where it is marked obsolete.

NOTES

History

The classical BSD version of this function appeared in 4.2BSD. It sets the process's signal mask to sigmask. UNIX 95 standardized the incompatible System V version of this function, which removes only the specified signal sig from the process's signal mask. The unfortunate situation with two incompatible functions with the same name was solved by the sigsuspend(2) function, that takes a sigset_t * argument (instead of an int).

Linux notes

On Linux, this routine is a system call only on the Sparc (sparc64) architecture.

Glibc uses the BSD version if the _BSD_SOURCE feature test macro is defined and none of _POSIX_SOURCE, _POSIX_C_SOURCE, _XOPEN_SOURCE, _GNU_SOURCE, or _SVID_SOURCE is defined. Otherwise, the System V version is used, and feature test macros must be defined as follows to obtain the declaration:

*: Since glibc 2.26: _XOPEN_SOURCE >= 500
*: Glibc 2.25 and earlier: _XOPEN_SOURCE

Since glibc 2.19, only the System V version is exposed by <signal.h>; applications that formerly used the BSD sigpause() should be amended to use sigsuspend(2).

COLOPHON

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