NAME

nanosleep — high resolution sleep

SYNOPSIS

#include <time.h>

int
nanosleep(const struct timespec *timeout, struct timespec *remainder);

DESCRIPTION

The nanosleep() function suspends execution of the calling thread for at least the given timeout. Delivery of an unmasked signal terminates this sleep early, even if SA_RESTART is set with sigaction(2) for the interrupting signal.

RETURN VALUES

If nanosleep() sleeps the full timeout without interruption, it returns 0. Unless remainder is NULL, it is set to zero.

If nanosleep() is interrupted by a signal, it returns -1 and the global variable errno is set to EINTR. Unless remainder is NULL, it is set to the unslept portion of the timeout.

Otherwise, nanosleep() returns -1 and the global variable errno is set to indicate the error.

ERRORS

nanosleep() will fail if:

[EINTR]

The call is interrupted by the delivery of a signal.

[EINVAL]

timeout specifies a nanosecond value less than zero or greater than or equal to one billion, or a second value less than zero.

[EFAULT]

timeout points to memory that is not a valid part of the process address space.

[EFAULT]

remainder is not NULL and points to memory that is not a valid part of the process address space.

SEE ALSO

sleep(1), sigaction(2), sleep(3)

STANDARDS

The nanosleep() function conforms to IEEE Std 1003.1-2008 (“POSIX.1”).

HISTORY

The predecessor of this system call, sleep(), first appeared in Version 2 AT&T UNIX. It was removed in Version 7 AT&T UNIX and replaced with a C library implementation based on alarm(3) and signal(3).

The nanosleep() function first appeared in IEEE Std 1003.1b-1993 (“POSIX.1b”).

This implementation of nanosleep() first appeared in NetBSD 1.3 and was ported to OpenBSD 2.1.