개요

• 솔라나라에 설명된 어플리케이션에 대해 맨 페이지를 찾아 출력한다.
• MAN 페이지에 대한 설명은 윈디하나의 솔라나라: MAN 페이지을 참고하자.
• svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.

_sysctl(2)

SYSCTL(2)                  Linux Programmer's Manual                 SYSCTL(2)

NAME
       sysctl - read/write system parameters

SYNOPSIS
       #include <unistd.h>
       #include <linux/sysctl.h>

       int _sysctl(struct __sysctl_args *args);

       Note: There is no glibc wrapper for this system call; see NOTES.

DESCRIPTION
       Do not use this system call!  See NOTES.

       The _sysctl() call reads and/or writes kernel parameters.  For example,
       the  hostname,  or  the maximum number of open files.  The argument has
       the form

           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 */
           };

       This call does a search in a tree structure, possibly resembling a  di‐
       rectory  tree under /proc/sys, and if the requested item is found calls
       some appropriate routine to read or modify the value.

RETURN VALUE
       Upon successful completion, _sysctl() returns 0.  Otherwise, a value of
       -1 is returned and errno is set to indicate the error.

ERRORS
       EACCES, EPERM
              No search permission for one of the  encountered  "directories",
              or no read permission where oldval was nonzero, or no write per‐
              mission where newval was nonzero.

       EFAULT The  invocation  asked  for the previous value by setting oldval
              non-NULL, but allowed zero room in oldlenp.

       ENOTDIR
              name was not found.

CONFORMING TO
       This call is Linux-specific, and should not be  used  in  programs  in‐
       tended to be portable.  A sysctl() call has been present in Linux since
       version 1.3.57.  It originated in 4.4BSD.  Only Linux has the /proc/sys
       mirror,  and the object naming schemes differ between Linux and 4.4BSD,
       but the declaration of the sysctl() function is the same in both.

NOTES
       Glibc does not provide a wrapper for this system call;  call  it  using
       syscall(2).   Or  rather...  don't call it: use of this system call has
       long been discouraged, and it is so unloved that it is likely to disap‐
       pear in a future kernel version.  Since Linux 2.6.24, uses of this sys‐
       tem call result in warnings in the kernel log.   Remove  it  from  your
       programs now; use the /proc/sys interface instead.

       This  system  call  is available only if the kernel was configured with
       the CONFIG_SYSCTL_SYSCALL option.

BUGS
       The object names vary between kernel versions, making this system  call
       worthless for applications.

       Not all available objects are properly documented.

       It  is  not  yet  possible  to  change  operating  system by writing to
       /proc/sys/kernel/ostype.

EXAMPLE
       #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);
       }

SEE ALSO
       proc(5)

COLOPHON
       This page is part of release 5.02 of the Linux  man-pages  project.   A
       description  of  the project, information about reporting bugs, and the
       latest    version    of    this    page,    can     be     found     at
       https://www.kernel.org/doc/man-pages/.

Linux                             2019-03-06                         SYSCTL(2)