USLEEP(3) |
FreeBSD Library Functions Manual |
USLEEP(3) |
NAME
usleep —
suspend process execution for an interval measured in microseconds
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include < unistd.h>
int
usleep( useconds_t microseconds);
DESCRIPTION
The
usleep() function suspends execution of the calling process until either
microseconds microseconds have elapsed or a signal is delivered to the process and its action is to invoke a signal-catching function or to terminate the process. System activity may lengthen the sleep by an indeterminate amount.
This function is implemented using nanosleep(2) by pausing for microseconds microseconds or until a signal occurs. Consequently, in this implementation, sleeping has no effect on the state of process timers, and there is no special handling for SIGALRM.
RETURN VALUES
The
usleep() function returns the value 0 if successful; otherwise the value -1 is returned and the global variable
errno is set to indicate the error.
ERRORS
The
usleep() function will fail if:
-
[
EINTR]
-
A signal was delivered to the process and its action was to invoke a signal-catching function.
HISTORY
The
usleep() function appeared in
4.3BSD.