usleep — suspend execution for microsecond intervals
#define _XOPEN_SOURCE 500 /* Or: #define _BSD_SOURCE */ #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.
Interrupted by a signal.
usec
is not
smaller than 1000000. (On systems where that is
considered an error.)
4.3BSD, POSIX.1-2001. POSIX.1-2001 declares this function obsolete; use nanosleep(2) instead.
On the original BSD implementation, and in glibc before
version 2.2.2, the return type of this function is void
. The POSIX version
returns int
, and
this is also the prototype used since 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);
The interaction of this function with the SIGALRM signal, and with other timer functions such as alarm(3), sleep(3), nanosleep(2), setitimer(2), timer_create(3), timer_delete(3), timer_getoverrun(3), timer_gettime(3), timer_settime(3), ualarm(3) is unspecified.
alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), ualarm(3), sleep(3), feature_test_macros(7), time(7)
|