2.11BSD#431 - /usr/man/cat3/usleep.0

SLEEP(3)	    UNIX Programmer's Manual		 SLEEP(3)


NAME
     sleep, usleep - suspend process execution

SYNOPSIS
     #include <unistd.h>

     unsigned int
     sleep(seconds)
	   unsigned int seconds;

     void
     usleep(microseconds)
	    long microseconds;

DESCRIPTION
     The sleep function suspends execution of the calling process
     for seconds of clock time, or until interrupted by a signal.

     The usleep function suspends execution of the calling pro-
     cess for microseconds of clock time, or until interrupted by
     a signal.

     System activity may lengthen the suspension.

RETURN VALUES
     The sleep function returns 0, or if interrupted before
     seconds, the amount not slept (the requested time minus the
     time actually slept) in seconds.  The usleep function does
     not return anything (meaningful).

SEE ALSO
     select(2)

COMPATIBILITY
     Previous implementations of sleep and usleep re-suspended
     the process if interrupted by a signal.  This implementation
     has been changed to return in that case, to conform to POSIX
     1003.1-88.

     On the PDP-11 the previous version of usleep took a u_int as
     the input parameter.  This has been changed to be long so
     that usleep can be used for more than 65 milliseconds (a
     u_int could only count 65535 microseconds) of sleep.  Thus
     it is now possible for usleep to handle longer sleep dura-
     tions than sleep.

BUGS
     On the PDP-11 the clock resolution is limited to the line
     frequency (usually 60Hz in the U.S.A. and 50Hz elsewhere).

HISTORY
     A usleep function appeared in 4.3BSD.  A sleep function


Printed 11/26/99	September 26,1997			1


SLEEP(3)	    UNIX Programmer's Manual		 SLEEP(3)


     appeared in V7.


Printed 11/26/99	September 26,1997			2