@c ----------------------------------------------------------------------
@node usleep, process
@findex usleep
@subheading Syntax

@example
#include <unistd.h>

unsigned usleep(unsigned usec);
@end example

@subheading Description

This function pauses the program for @var{usec} microseconds.  Note
that, since @code{usleep} calls @code{clock} internally, and the latter
has a 55-msec granularity, any argument less than 55@dmn{msec} will result in
a pause of random length between 0 and 55 msec.  Any argument less
than 11@dmn{msec} (more precisely, less than 11264 microseconds), will always
result in zero-length pause (because @code{clock} multiplies the timer
count by 5).  @xref{clock}.

@subheading Return Value

The number of unslept microseconds (i.e. zero).

@subheading Portability

@portability !ansi, !posix

@subheading Example

@example
usleep(500000);
@end example