Section (3) usleep
usleep — suspend execution for microsecond intervals
suspends execution of the calling thread for (at least)
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.
returns 0 on success. On error, −1 is returned, with
errno set to indicate the cause
of the error.
Interrupted by a signal; see signal(7).
usecis greater than or equal to 1000000. (On systems where that is considered an error.)
For an explanation of the terms used in this section, see attributes(7).
4.3BSD, POSIX.1-2001. POSIX.1-2001 declares this function
obsolete; use nanosleep(2) instead.
POSIX.1-2008 removes the specification of
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 and POSIX.1-2001.
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(2), sleep(3), nanosleep(2), setitimer(2), timer_create(2), timer_delete(2), timer_getoverrun(2),
timer_gettime(2), timer_settime(2), ualarm(3) is
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Copyright 1993 David Metcalfe (davidprism.demon.co.uk)
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Linux libc source code
Lewine_zsingle_quotesz_s _POSIX Programmer_zsingle_quotesz_s Guide_ (O_zsingle_quotesz_Reilly & Associates, 1991)
386BSD man pages
Modified 1993-07-24 by Rik Faith (faithcs.unc.edu)
Modified 2001-04-01 by aeb
Modified 2003-07-23 by aeb