NAME

usleep — suspend execution for interval in microseconds

SYNOPSIS

#include <unistd.h>

int
usleep(useconds_t useconds);

DESCRIPTION

The usleep() function suspends the caller from execution for the number of microseconds specified by the useconds argument. The actual suspension time might be less than requested because any caught signal will terminate usleep() following execution of that signal's catching routine. The suspension time might be longer than requested by an arbitrary amount because of the scheduling of other activity in the system.

If the value of useconds is 0, then the call has no effect.

The use of the usleep function has no effect on the action or blockage of any signal. In a multithreaded process, only the invoking thread is suspended from execution.

RETURN VALUES

On completion, usleep() returns 0. There are no error returns.

ERRORS

No errors are returned.

USAGE

The usleep() function is included for its historical usage and is Obsolete. The nanosleep(3C) function is preferred over this function.

INTERFACE STABILITY

Obsolete Standard.

MT-LEVEL

Safe.

SEE ALSO

nanosleep(3C), sleep(3C), unistd.h(3HEAD), standards(7)

STANDARDS

The usleep() function is available in the following compilation environments. See standards(7).

• X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”)
• Version 2 of the Single UNIX Specification (“SUSv2”)
• Version 3 of the Single UNIX Specification (“SUSv3”)

It is marked obsolete in Version 3 of the Single UNIX Specification (“SUSv3”), and was removed from IEEE Std 1003.1-2008 (“POSIX.1”).