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.\" This manpage is copyright (C) 1992 Drew Eckhardt,
.\"                 copyright (C) 1995 Michael Shields.
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
.\" Modified 1995-05-18 by Jim Van Zandt <jrv@vanzandt.mv.com>
.\" Sun Feb 11 14:07:00 MET 1996  Martin Schulze  <joey@linux.de>
.\"	* layout slightly modified
.\"
.\" Modified Mon Oct 21 23:05:29 EDT 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified Thu Feb 24 01:41:09 CET 2000 by aeb
.\" Modified Thu Feb  9 22:32:09 CET 2001 by bert hubert <ahu@ds9a.nl>, aeb
.\"
.\" Japanese Version Copyright (c) 1997 HANATAKA Shinya
.\"         all rights reserved.
.\" Translated Sun Feb 23 22:43:33 JST 1997
.\"         by HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Modified Sun Mar 12 16:22:57 JST 2000
.\"         by HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated & Modified Mon Jun  4 01:13:06 JST 2001
.\"         by Yuichi SATO <ysato@h4.dion.ne.jp>
.\" Updated & Modified Sun Jul  1 09:58:38 JST 2001 by Yuichi SATO
.\" Updated & Modifedd Mon Jan 14 07:15:45 JST 2002 by Yuichi SATO
.\"
.\"WORD:	synchronous		Ʊ
.\"WORD:	multiplexing		¿Ų
.\"WORD:	descriptor		ǥץ
.\"WORD:	macro			ޥ
.\"WORD:	block			(block)
.\"WORD:	block			ػ(block)
.\"WORD:	signal			ʥ
.\"WORD:	timeout			ڤ(timeout)
.\"WORD:	portable		ܿΤ
.\"
.TH SELECT 2 2001-02-09 "Linux 2.4" "Linux Programmer's Manual"
.SH ̾
select, pselect, FD_CLR, FD_ISSET, FD_SET, FD_ZERO \- ¿Ų줿 I/O ƱȤ
.SH 
/* POSIX 1003.1-2001 ˽ */
.br
.B #include <sys/select.h>
.sp
/* εʤ˽ */
.br
.B #include <sys/time.h>
.br
.B #include <sys/types.h>
.br
.B #include <unistd.h>
.sp
\fBint select(int \fIn\fB, fd_set *\fIreadfds\fB,
fd_set *\fIwritefds\fB, fd_set *\fIexceptfds\fB,
struct timeval *\fItimeout\fB);
.sp
\fBint pselect(int \fIn\fB, fd_set *\fIreadfds\fB,
fd_set *\fIwritefds\fB, fd_set *\fIexceptfds\fB,
const struct timespec *\fItimeout\fB, const sigset_t *\fIsigmask\fB);
.sp
.BI "FD_CLR(int " fd ", fd_set *" set );
.br
.BI "FD_ISSET(int " fd ", fd_set *" set );
.br
.BI "FD_SET(int " fd ", fd_set *" set );
.br
.BI "FD_ZERO(fd_set *" set );
.fi
.SH 
ؿ
.B select

.B pselect
ϡʣΥե롦ǥץ (file descriptor) ƻ뤷
ξ֤ѲΤԤġ
.PP
2 Ĥδؿεǽϡ3 Ĥΰ㤤ʳƱǤ:
.TP
(i)
.B select
ؿ
.I ¤ timeval
(áޥ) ɽڤ (timeout) Ȥ

.B pselect

.I ¤ timespec
(áʥ) ɽڤ (timeout) Ȥ
.TP
(ii)
.B select
ؿϡĤ֤򼨤
.I timeout
ѥ᡼򹹿뤳Ȥ롣
.B pselect
ؿϡΥѥ᡼ѹʤ
.TP
(iii)
.B select
ؿˤ
.I sigmask
ѥ᡼ʤ
.I sigmask
 NULL ȤƸƤӽФ
.B pselect
Ʊư򤹤롣
.PP
ĤΩǥץν礬ƻ뤵롣
.I readfds
˥ꥹȤ줿Τɤ߹ߤǽɤƻ뤹롣
(Τˤϡ (block) ɤळȤǤ뤫Ĵ٤롣
äˡե롦ǥץեνü (end-of-file) 
ޤޤ)
.I writefds
˥ꥹȤ줿Τߤ˽񤭹ߤǽɤƻ뤹롣
.I exceptfds
ˤΤ㳰δƻԤʤλˡºݤˤɤ
ǥץξ֤Ѳ˽礬ѹ롣
.PP
뤿˻ͤĤΥޥ (macro) 󶡤롣
.B FD_ZERO
Ͻõ (clear) 롣
.B FD_SET

.B FD_CLR
Ͻ˥ǥץäꤹ롣
.B FD_ISSET
Ͻ˥ǥץ뤫ɤĴ٤; 
.B select
λǤ롣
.PP
.I n
ϻĤνˤǥץκͤ 1 ­Ρ
.PP
.I timeout

.B select
֤äƤޤǤηв֤ξ¡ 0 ˤ뤳ȤǤ
ξ
.B select
Ϥ֤äƤ롣
(ϥݡ (polling) 򤹤ΤΩġ)
⤷
.I timeout
 NULL (ڤ (timeout) ̵)
ꤵȡ
.B select
̵¤ (block) 롣
.PP
.I sigmask
ϥʥޥ
.RB ( sigprocmask (2)
򻲾) ؤΥݥ󥿤Ǥ롣
.I sigmask
 NULL Ǥʤ硢
.B pselect

.I sigmask
ؤƤ륷ʥޥǸߤΥʥޥ֤롣
 `select' ؿ¹Ԥ롣
ơΥʥޥ˺Ƥ᤹
.PP
ֲ餫Υ٥
(ʥեǥץѲ) ԤȤˤϡ
֤򤱤뤿 atomic ʥƥȤɬפˤʤפȤΤ
.B pselect
ιͤǤ롣
(ʥϥɥ餬ե饰ꤷ硢
ʥ뤬ƥȤľ夫ĸƤӽФľϤ
.BR select ()
θƤӽФ³ե饰ΥƥȤ򤹤ȡ
Υϥ󥰤򤹤뤫⤷ʤ

.B pselect
Ͻ˥ʥػ (block) ơä륷ʥ
򤱤ƹߤ
.I sigmask

.BR pselect ()
ƤӽФȤǤ롣)
Ԥ Linux ˤ
.IR pselect ()
ƥॳ뤬ʤΤǡ
ߤ glibc2 롼ˤ̤ˤζ礬¸ߤ롣
.SH ֤
硢
.B select

.B pselect
ϥǥץ˴ޤޤƤǥץο֤
ⵯ餺˻ڤˤʤä硢
ǥץο 0 ˤʤ뤳Ȥ⤢롣
顼ʤ \-1 ֤
.I errno
Ŭڤͤꤵ; 
.I timeout
̤ȤʤΤǡ顼θϤƤꤷƤϤʤʤ
.SH 顼
.TP
.B EBADF
Τɤ줫̵ʥեǥץͿ줿
.TP
.B EINTR
ػ (block) Ƥʤʥ (signal) 
.TP
.B EINVAL
.I n
Ǥ롣
.TP
.B ENOMEM
.B select
ơ֥˥꡼Ƥ뤳ȤǤʤä
.SH 
δؿ˴ޤޤ֤ι¤Τϡ
.I <sys/time.h>
ƤꡢΤ褦ˤʤäƤ롣

.RS
.nf
struct timeval { 
    long    tv_sec;         /*  */
    long    tv_usec;        /* ޥ */
};
.fi
.RE

.RS
.nf
struct timespec {
    long    tv_sec;         /*  */
    long    tv_nsec;        /* ʥ */
};
.fi
.RE
.PP
ñ̰ʲ٤ǥ꡼ (sleep) ¸
ܿ (portable) ι⤤ˡȤơ
.B select
ˤ뻰ĤνƤ
.I n
 0
.I timeout
 NULL ǤʤͤꤷƸƤӽФȤɤ롣
.PP
Linux Ǥϡؿ
.B select

.I timeout
 (sleep) Ƥʤ֤̤ȿǤ褦ˤ
¾ΤۤȤɤΥץơǤϤΤ褦ˤʤäƤʤ

.I timeout
ɤ߼ Linux Υɤ¾Υڥ졼ƥ󥰡ƥذܿ
 롼פ timval ¤Τ˺ƻѤʣ 
.B select
ԤʤäƤ륳ɤ Linux ذܿξ򵯤
.B select
֤äƤ
.I timeout
̤Ǥȹͤ٤Ǥ롣
.\" .PP
.\" BSD ǤϥॢȤäƤ⡢
.\" եǥץӥåȤѤʤפʹȤ롣
.\" Linux  SUSv2 ˽äƤꡢ
.\" ॢȤκݤˤϥӥåȥޥ 0 ˤפȤΤϳΤ˻¤Ǥ롣
.SH 
.nf
#include <stdio.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>

int
main(void) {
    fd_set rfds;
    struct timeval tv;
    int retval;

    /* stdin (fd 0) ƻ뤷Ϥäɽ롣*/
    FD_ZERO(&rfds);
    FD_SET(0, &rfds);
    /* 5 ôִƻ뤹롣*/
    tv.tv_sec = 5;
    tv.tv_usec = 0;

    retval = select(1, &rfds, NULL, NULL, &tv);
    /* λǤ tv ͤꤷƤϤʤʤ*/

    if (retval)
        printf("ǡǤޤ\\n");
        /* FD_ISSET(0, &rfds)  true ˤʤ롣*/
    else
        printf("5 ð˥ǡϤޤǤ\\n");

    return 0;
}
.fi
.SH 
4.4BSD
.RB ( select
ؿ 4.2BSD Ǻǽ˸줿)
̤ BSD Υåؤ򥵥ݡȤ BSD ʳΥƥ
(System V Ѽޤ) ؤΰܿޤϤ줫ΰܿǤ롣
 System V ѼŵŪ timeout ѿꤹΤФơ
BSD ѼǤꤷʤȤդ뤳ȡ
.PP
.B pselect
ؿ IEEE Std 1003.1g-2000 (POSIX.1g) 
POSIX 1003.1-2001 ΰƤ롣
δؿ glibc2.1 ʹߤˤ롣
glibc2.0 ˤ⤳̾δؿ뤬
.I sigmask
ѥ᡼Ȥʤ
.SH 
ץȥפ˴ؤƤϡΤʤξǤ
.B select
Ȥ
.I <time.h>
򥤥󥯥롼ɤФ褤
POSIX 1003.1-2001 βǤϡ
.B select

.B pselect
Ȥ
.I <sys/select.h>
򥤥󥯥롼ɤФ褤
إåե
.I <sys/select.h>
 libc4  libc5 ˤϤʤglibc 2.0 ʹߤ¸ߤ롣
Ȥ glibc 2.0 Ǥ
.B pselect
ΥץȥפְäƤ롣
glibc 2.1-2.2.1 Ǥ
.B _GNU_SOURCE
Ƥˡ
.B pselect
󶡤롣
glibc 2.2.2-2.2.4 Ǥ
.B _XOPEN_SOURCE
Ƥơͤ 600 ʾǤ
.B pselect
󶡤롣
̵ POSIX 1003.1-2001 ʹߤǤϡǥեȤǥץȥפ󶡤롣
.SH Ϣ
Ȼν񤫤줿塼ȥꥢȤƤϡ
.BR select_tut (2)
򻲾Ȥ뤳ȡ
.LP
ȴϢȤƤϡ
.BR accept (2),
.BR connect (2),
.BR poll (2),
.BR read (2),
.BR recv (2),
.BR send (2),
.BR sigprocmask (2),
.BR write (2)
ʤɤ򻲾Ȥ뤳ȡ