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USLEEP(3) FreeBSD Library Functions Manual USLEEP(3)
NAME
usleep - suspend thread 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 thread until
either microseconds microseconds have elapsed or a signal is delivered to
the thread 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 calling thread and its
action was to invoke a signal-catching function.
SEE ALSO
nanosleep(2), sleep(3)
HISTORY
The usleep() function appeared in 4.3BSD.
FreeBSD 14.0-RELEASE-p6 February 11, 2021 FreeBSD 14.0-RELEASE-p6