.\" Copyright (C) 1996 Andries Brouwer (aeb@cwi.nl)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" 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.
.\"
.\" 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.\" manual page may be incorrect or out-of-date.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.
.\"
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\"
.\" Written 11 April 1996 by Andries Brouwer <aeb@cwi.nl>
.\" 960412: Added comments from Stephen Tweedie
.\" Modified Tue Oct 22 22:28:41 1996 by Eric S. Raymond <esr@thyrsus.com>
.\" Modified Mon Jan  5 20:31:04 1998 by aeb.
.\"
.\" Japanese Version Copyright (c) 1997-1998 HANATAKA Shinya
.\"         all rights reserved.
.\" Translated 1997-12-12, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Modified 1998-05-11, HANATAKA Shinya <hanataka@abyss.rim.or.jp>
.\" Updated 2007-10-11, Akihiro MOTOKI <amotoki@dd.iij4u.or.jp>, LDP v2.66
.\"
.\"WORD:	parameter		ѥ᡼
.\"WORD:	kernel			ͥ
.\"WORD:	hostname		ۥȥ͡
.\"WORD:	open			ץ
.\"WORD:	directory		ǥ쥯ȥ
.\"WORD:	tree			ĥ꡼
.\"
.TH SYSCTL 2 2007-09-22 "Linux" "Linux Programmer's Manual"
.SH ̾
sysctl \- ƥࡦѥ᡼ɤ߽񤭤
.SH 
.nf
.B #include <unistd.h>
.br
.B #include <linux/sysctl.h>
.sp
.BI "int _sysctl(struct __sysctl_args *" args );
.fi
.SH 
.BR _sysctl ()
ϥͥѥ᡼ɤ߽񤭤롣㤨С
ۥȥ͡Ʊ˥ץǤեκʤɡ
ϰʲηǤ롣
.PP
.in +4n
.nf
struct __sysctl_args {
    int    *name;    /* integer vector describing variable */
    int     nlen;    /* length of this vector */
    void   *oldval;  /* 0 or address where to store old value */
    size_t *oldlenp; /* available room for old value,
                        overwritten by actual size of old value */
    void   *newval;  /* 0 or address of new value */
    size_t  newlen;  /* size of new value */
};
.fi
.in
.PP
Υ
.I /proc/sys
βΥǥ쥯ȥꡦĥ꡼˻ڹ¤(tree structure)򸡺롣
ơ׵ᤵ줿ܤĤäŬڤʥ롼ƤӽФ
ͤɤ꽤ꤹ롣
.SH ֤

.BR _sysctl ()
 0 ֤Ԥ硢\-1 ֤졢
.I errno
Υ顼򼨤ͤꤵ롣
.SH 顼
.TP
.B EFAULT
.I oldval
 NULL Ǥʤͤꤷơͤ׵ᤷƤΤˡ
.I oldlenp
˶ʤ
.TP
.B ENOTDIR
.I name
Ĥʤä
.TP
.B EPERM
֥ǥ쥯ȥפΤɤ줫˸Ĥʤä
.I oldval
 0 ǤʤΤɤ߹ߵĤʤä
.I newval
 0 ǤʤΤ˽񤭹ߵĤʤä
.SH 
Υ Linux ͭǤꡢܿտޤץǻѤƤ
ʤ
.SH 
.BR sysctl ()

Linux ΥС 1.3.57 ¸ߤƤ롣
 4.4BSD ͳ褷Ƥ롣Linux 
.I /proc/sys
˼̤(mirror)äƤꡢܤ̾դ Linux  4.4BSD Ǥ
ۤäƤ롣
.BR sysctl ()
ؿξƱǤ롣
.SH 
glibc ϤΥƥॳФåѡؿ󶡤Ƥʤ
.BR syscall (2)
ȤäƸƤӽФȡ

ȤϡΥƥॳƤӽФʤȡ
Ĺ֤ΥƥॳλѤ侩ȤƤꡢ
־ΥСΥͥǺ褦פȸۤɤǤ롣
.\" http://lwn.net/Articles/247243/ 
ʤΥץˤΥƥॳ뤬СˤǤ뤳ȡ

.I /proc/sys
󥿡եѤ뤳ȡ
.SH Х
֥Ȥ̾ϡͥΥС󤴤Ȥ˰ۤʤäƤ롣
ΤᡢΥƥࡦϥץꥱˤȤä
̵ͤʤΤȤʤäƤ롣
.PP
ƤβǽʹܤΤ˵ҤƤ櫓ǤϤʤ
.PP
ΤȤ
.I /proc/sys/kernel/ostype
˽񤭹ळȤǥڡ졼ƥ󥰡ƥѤ뤳ȤϤǤʤ
.SH 
.nf
#define _GNU_SOURCE
#include <unistd.h>
#include <sys/syscall.h>
#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#include <linux/sysctl.h>

int _sysctl(struct __sysctl_args *args );

#define OSNAMESZ 100

int
main(void)
{
    struct __sysctl_args args;
    char osname[OSNAMESZ];
    size_t osnamelth;
    int name[] = { CTL_KERN, KERN_OSTYPE };

    memset(&args, 0, sizeof(struct __sysctl_args));
    args.name = name;
    args.nlen = sizeof(name)/sizeof(name[0]);
    args.oldval = osname;
    args.oldlenp = &osnamelth;

    osnamelth = sizeof(osname);

    if (syscall(SYS__sysctl, &args) == \-1) {
        perror("_sysctl");
        exit(EXIT_FAILURE);
    }
    printf("This machine is running %*s\\n", osnamelth, osname);
    exit(EXIT_SUCCESS);
}
.fi
.SH Ϣ
.BR proc (5)