php man page for sleep

SLEEP(3)								 1								  SLEEP(3)

sleep - Delay execution

SYNOPSIS
       int sleep (int  $seconds)

DESCRIPTION
	Delays the program execution for the given number of $seconds.

PARAMETERS
	      o $seconds
		- Halt time in seconds.

RETURN VALUES
	Returns zero on success, or FALSE on error.

	If  the  call  was interrupted by a signal, sleep(3) returns a non-zero value. On Windows, this value will always be 192 (the value of the
       WAIT_IO_COMPLETION constant within the Windows API). On other platforms, the return value will be the number of seconds left to sleep.

ERRORS
/EXCEPTIONS
	If the specified number of $seconds is negative, this function will generate a E_WARNING.

CHANGELOG
       +--------+---------------------------------------------------+
       |Version |						    |
       |	|						    |
       |	|		     Description		    |
       |	|						    |
       +--------+---------------------------------------------------+
       | 5.3.4	|						    |
       |	|						    |
       |	|  Before PHP 5.3.4, on  Windows,  sleep(3)  always |
       |	| returns  NULL when sleep has occurred, regardless |
       |	| of whether the sleep was interrupted or not.	    |
       |	|						    |
       +--------+---------------------------------------------------+
EXAMPLES
       Example #1

	      sleep(3) example

	      <?php

	      // current time
	      echo date('h:i:s') . "
";

	      // sleep for 10 seconds
	      sleep(10);

	      // wake up !
	      echo date('h:i:s') . "
";

	      ?>

	       This example will output (after 10 seconds)

	      05:31:23
	      05:31:33

SEE ALSO
       usleep(3), time_nanosleep(3), time_sleep_until(3), set_time_limit(3).

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