select.h

<sys/select.h>(P)					    <sys/select.h>(P)



NAME
       sys/select.h - select types

SYNOPSIS
       #include <sys/select.h>

DESCRIPTION
       The  <sys/select.h>  header  shall  define  the timeval structure that
       includes at least the following members:


	      time_t	     tv_sec	 Seconds.
	      suseconds_t    tv_usec	 Microseconds.

       The time_t and suseconds_t types shall  be  defined  as	described  in
       <sys/types.h> .

       The sigset_t type shall be defined as described in <signal.h> .

       The timespec structure shall be defined as described in <time.h> .

       The <sys/select.h> header shall define the fd_set type as a structure.

       Each of the following may be declared as a function, or defined	as  a
       macro, or both:

       void FD_CLR(int fd, fd_set *fdset)

	      Clears  the bit for the file descriptor fd in the file descrip-
	      tor set fdset.

       int FD_ISSET(int fd, fd_set *fdset)

	      Returns a non-zero value if the bit for the file descriptor  fd
	      is set in the file descriptor set by fdset, and 0 otherwise.

       void FD_SET(int fd, fd_set *fdset)

	      Sets  the bit for the file descriptor fd in the file descriptor
	      set fdset.

       void FD_ZERO(fd_set *fdset)

	      Initializes the file descriptor set fdset to have zero bits for
	      all file descriptors.


       If implemented as macros, these may evaluate their arguments more than
       once, so applications should ensure that the arguments they supply are
       never expressions with side effects.

       The following shall be defined as a macro:

       FD_SETSIZE

	      Maximum number of file descriptors in an fd_set structure.


       The  following  shall be declared as functions and may also be defined
       as macros. Function prototypes shall be provided.


	      int  pselect(int, fd_set *restrict, fd_set *restrict, fd_set *restrict,
		       const struct timespec *restrict, const sigset_t *restrict);
	      int  select(int, fd_set *restrict, fd_set *restrict, fd_set *restrict,
		       struct timeval *restrict);

       Inclusion of the <sys/select.h> header may make	visible	 all  symbols
       from the headers <signal.h>, <sys/time.h>, and <time.h>.

       The following sections are informative.

APPLICATION USAGE
       None.

RATIONALE
       None.

FUTURE DIRECTIONS
       None.

SEE ALSO
       <signal.h>  ,  <sys/time.h>  ,  <sys/types.h>  , <time.h> , the System
       Interfaces volume of IEEE Std 1003.1-2001, pselect(), select()

COPYRIGHT
       Portions of this text are reprinted and reproduced in electronic	 form
       from  IEEE Std 1003.1, 2003 Edition, Standard for Information Technol-
       ogy -- Portable Operating System Interface  (POSIX),  The  Open	Group
       Base  Specifications Issue 6, Copyright (C) 2001-2003 by the Institute
       of Electrical and Electronics Engineers, Inc and The  Open  Group.  In
       the  event  of  any  discrepancy between this version and the original
       IEEE and The Open Group Standard, the original IEEE and The Open Group
       Standard	 is  the  referee  document.  The  original  Standard  can be
       obtained online at http://www.opengroup.org/unix/online.html .



POSIX				     2003		    <sys/select.h>(P)