Originální popis anglicky:
usleep - suspend execution for microsecond intervals
Návod, kniha: Linux Programmer's Manual
/* BSD version */
#include <unistd.h>
void usleep(unsigned long usec);
/* SUSv2 version */
#define _XOPEN_SOURCE 500
#include <unistd.h>
int usleep(useconds_t usec);
The
usleep() function suspends execution of the calling process for (at
least)
usec microseconds. The sleep may be lengthened slightly by any
system activity or by the time spent processing the call or by the granularity
of system timers.
None (BSD). Or: 0 on success, -1 on error (SUSv2).
- EINTR
- Interrupted by a signal.
- EINVAL
- usec is not smaller than 1000000. (On systems where
that is considered an error.)
BSD 4.3. The SUSv2 version returns int, and this is also the prototype used by
glibc 2.2.2. Only the EINVAL error return is documented by SUSv2.
The type
useconds_t is an unsigned integer type capable of holding
integers in the range [0,1000000]. Programs will be more portable if they
never mention this type explicitly. Use
#include <unistd.h>
...
unsigned int usecs;
...
usleep(usecs);
This type is defined by
<sys/types.h> included by
<unistd.h> but glibc defines it only when _XOPEN_SOURCE has a
value not less than 500, or both _XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED are
defined.
The interaction of this function with the SIGALRM signal, and with other timer
functions such as
alarm(),
sleep(),
nanosleep(),
setitimer(),
timer_create(),
timer_delete(),
timer_getoverrun(),
timer_gettime(),
timer_settime(),
ualarm() is unspecified.
This function is obsolete. Use
nanosleep(2) or
setitimer(2)
instead.
alarm(2),
getitimer(2),
nanosleep(2),
select(2),
setitimer(2),
sleep(3)
