NAME

nanosleep — high resolution sleep

SYNOPSIS

#include <time.h>

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

DESCRIPTION

nanosleep() suspends execution of the calling process for the duration specified by timeout. An unmasked signal will cause it to terminate the sleep early, regardless of the SA_RESTART value on the interrupting signal.

RETURN VALUES

If the nanosleep() function returns because the requested duration has elapsed, the value returned will be zero.

If the nanosleep() function returns due to the delivery of a signal, the value returned will be -1, and the global variable errno will be set to indicate the interruption. If remainder is non-null, the timespec structure it references is updated to contain the unslept amount (the requested duration minus the duration actually slept).

ERRORS

If any of the following conditions occur, the nanosleep() function shall return -1 and set errno to the corresponding value.

[EINTR]

nanosleep() was interrupted by the delivery of a signal.

[EINVAL]

timeout specified a nanosecond value less than zero or greater than 1000 million, or a second value less than zero or greater than 100 million.

[EFAULT]

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

SEE ALSO

sleep(1), sleep(3)

STANDARDS

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

HISTORY

The predecessor of this system call, sleep(), appeared in Version 3 AT&T UNIX, but was removed when alarm(3) was introduced into Version 7 AT&T UNIX. The nanosleep() system call has been available since NetBSD 1.3 and was ported to OpenBSD 2.1 and FreeBSD 3.0.