.\" Hey Emacs! This file is -*- nroff -*- source.
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.\" This manpage is Copyright (C) 1992 Drew Eckhardt;
.\"                               1993 Michael Haardt, Ian Jackson.
.\"
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.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
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.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
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.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
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.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Modified Sat Jul 24 00:06:00 1993 by Rik Faith <faith@cs.unc.edu>
.\" Modified Wed Jan 17 16:02:32 1996 by Michael Haardt
.\"   <michael@cantor.informatik.rwth-aachen.de>
.\" Modified Thu Apr 11 19:26:35 1996 by Andries Brouwer <aeb@cwi.nl>
.\" Modified Sun Jul 21 18:59:33 1996 by Andries Brouwer <aeb@cwi.nl>
.\" Modified Fri Jan 31 16:47:33 1997 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified Sat Jul 12 20:45:39 1997 by Michael Haardt
.\"   <michael@cantor.informatik.rwth-aachen.de>
.\"
.\" Japanese Version Copyright (c) 1997 HANATAKA Shinya
.\"         all rights reserved.
.\" Translated 1997-02-23, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Modified 1997-09-28, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated & Modified 2005-02-24, Yuichi SATO <ysato444@yahoo.co.jp>
.\" Updated 2005-09-06, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>
.\" Updated 2005-10-14, Akihiro MOTOKI
.\" Updated 2008-02-10, Akihiro MOTOKI, LDP v2.77
.\"
.\"WORD:	descriptor		ǥץ
.\"WORD:	buffer			Хåե
.\"WORD:	signal			ʥ
.\"WORD:	process group		ץ롼
.\"WORD:	backgraound		Хå
.\"WORD:	orphan			Ω
.\"WORD:	open			ץ
.\"WORD:	directory		ǥ쥯ȥ
.\"WORD:	object			֥
.\"
.TH READ 2 2007-11-15 "Linux" "Linux Programmer's Manual"
.SH ̾
read \- ե롦ǥץɤ߹
.SH 
.nf
.B #include <unistd.h>
.sp
.BI "ssize_t read(int " fd ", void *" buf ", size_t " count );
.fi
.SH 
.BR read ()
ϥե롦ǥץ (file descriptor)
.I fd

.I count
ХȤ
.I buf
ǻϤޤХåեɤ߹⤦Ȥ롣
.PP
.I count
 0 ʤС
.BR read ()
 0 ֤¾˲ⵯʤ
.I count

.B SSIZE_MAX
礭С̤Ǥʤ
.SH ֤
硢ɤ߹Хȿ֤ (0 ϥեν̣)
ե֤Ϥοʤ롣
ο׵ᤷ꾮äȤƤ⥨顼ǤϤʤ;
㤨кˤϼºݤˤοʤ (եκǸ˶ᤤΤ
ʤѥ (pipe) ü (terminal) ɤ߹Ǥ뤫⤷ʤ) 
.BR read ()
ʥ (signal) ˤäƳޤ줿ˤϵꤨ롣
顼ξϡ\-1 ֤졢
.I errno
Ŭڤꤵ롣ξϥե֤ѹ뤫ɤ
Ǥ롣
.SH 顼
.TP
.B EAGAIN
.B O_NONBLOCK
Ѥ (Non-blocking) I/O 򤵤Ƥꡢ
˥ǡɤ߹߲ǽǤʤä
.TP
.B EBADF
.I fd
ͭʥե롦ǥץǤʤɤ߹ߤΤ
ץ (open) Ƥʤ
.TP
.B EFAULT
.I buf
ǽʥɥ쥹֤γˤ롣
.TP
.B EINTR
Υǡɤ߹ޤʤ˥ʥ˳ޤ줿
.TP
.B EINVAL
.I fd
ɤ߹ߤŬƤʤ֥Ȥ򻲾ȤƤ롣
⤷ϡե뤬
.B O_DIRECT
ե饰ꤷƥץ󤵤Ƥ뤬
.I buf
˻ꤵ줿ɥ쥹
.I count
˻ꤵ줿͡
ߤΥե륪եåȤΤ줫
饤ȤŬڤǤ롣
.TP
.B EINVAL
.I fd

.BR timerfd_create (2)
θƤӽФǺ줿
.BR read ()
˴ְäΥХåեϤ줿
ʤ
.BR timerfd_create (2)
򻲾ȤΤȡ
.TP
.B EIO
I/O 顼㤨ХץХåɡץ롼פǡ
椷Ƥ tty ɤ߹⤦Ȥ
.B SIGTTIN
̵ (ignore) ޤ϶ػ (blocking) Ƥ䡢
Υץ롼פΩ (orphan) Ƥ˵롣
ޤǥơפɤǤ٥ I/O 顼
ȯˤⵯ롣
.TP
.B EISDIR
.I fd
ǥ쥯ȥ򻲾ȤƤ롣
.PP
.I fd
³Ƥ륪֥ȤˤäƤ¾Υ顼ⵯꤨ롣
POSIX Ǥϡ
餫Υǡɤ˳ߤä硢
.BR read ()

.RI ( errno

.B EINTR
ꤷ) \-1 ֤Ƥ褤
ɤ߹Хȿ֤Ƥ褤
.SH 
SVr4, 4.3BSD, POSIX.1-2001.
.SH 
NFS ˤơ̤Υǡɤ߹硢ǽλΤߤ˥ࡦ
פ졢³ǤϹʤ
ϥ饤¦°Υå󥰤ԤʤǤ롣
ʤʤС⤷Ƥ NFS 饤Ȥ st_atime (ǽե륢)
ι򥵡С餺饤¦ǥåɤळȤ­
СС¦Ǥ read ȯʤΤ st_atime ιϹԤʤ줫
UNIX Ǥϡ饤¦°Υå󥰤̵ˤ뤳Ȥǡ
뤳ȤǤ롣ۤȤɤξǤϤ³С
٤äѥեޥ󥹤㲼⤿餹
.PP
¿Υե륷ƥǥ
.B O_NONBLOCK
μϤʤƤѤय餤˽ʬ˹®ǤȹͤƤ롣
ǤΤ褦ʥեǥˤ
.B O_NONBLOCK
ѤǤʤ⤷ʤ
.SH Ϣ
.BR close (2),
.BR fcntl (2),
.BR ioctl (2),
.BR lseek (2),
.BR open (2),
.BR pread (2),
.BR readdir (2),
.BR readlink (2),
.BR readv (2),
.BR select (2),
.BR write (2),
.BR fread (3)