usleep(3)usleep(3)NAMEusleep - Suspend execution for an interval of time
SYNOPSIS
#include <unistd.h>
int usleep(
useconds_t useconds );
The following function declaration does not conform to current stan‐
dards and is supported only for backward compatibility:
#include <unistd.h>
void usleep(
unsigned useconds );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
usleep(): XPG4-UNIX
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies the number of microseconds to sleep.
DESCRIPTION
The usleep() function suspends the current process from execution for
the number of microseconds specified by the useconds parameter. Because
of other activity in the system, or because of the time spent in pro‐
cessing the call, the actual suspension time might be longer than spec‐
ified.
The useconds parameter must be less than 1,000,000. If the value of
useconds is 0 (zero), the usleep() function has no effect.
In a multithreaded environment, the sleep() function is redefined to
suspend the calling thread.
RETURN VALUES
On successful completion, the usleep() function returns 0 (zero). Oth‐
erwise, it returns -1 and sets errno to indicate the error.
ERRORS
The usleep() function sets errno to the specified values for the fol‐
lowing conditions: The interval specified in the useconds parameter
exceeds 1,000,000 microseconds.
SEE ALSO
Functions: getitimer(2), sigaction(2), sigvec(2), alarm(3), sleep(3)
Standards: standards(5)usleep(3)
