USLEEP(3) |
Library Functions Manual |
USLEEP(3) |
NAME
usleep — suspend execution for interval of 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 the number of microseconds specified by
microseconds have elapsed or a signal is delivered to the calling process and its action is to invoke a signal catching function or to terminate the process. The suspension time may be longer than requested due to the scheduling of other activity by the system.
The microseconds argument must be less than 1,000,000. If the value of microseconds is 0, then the call has no effect.
RETURN VALUES
On successful completion, usleep() returns 0. Otherwise, it returns -1 and sets errno to indicate the error.
ERRORS
The
usleep() function may fail if:
-
[EINVAL]
-
The microseconds interval specified 1,000,000 or more microseconds.
STANDARDS
The
usleep() function conforms to X/Open Portability Guide Issue 4, Version 2 (“XPG4.2”). It later appeared in the POSIX standard, but in IEEE Std 1003.1-2004 (“POSIX.1”) it was marked as legacy and the use of
nanosleep(2) was recommended instead. The IEEE Std 1003.1-2008 (“POSIX.1”) revision removed
usleep() from the specification.
HISTORY
The usleep() function appeared in 4.3BSD.