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SYSCTL(3)		    Library Functions Manual		     SYSCTL(3)

NAME
       sysctl, sysctlbyname, sysctlnametomib --	get or set system information

LIBRARY
       Standard	C Library (libc, -lc)

SYNOPSIS
       #include	<sys/sysctl.h>

       int
       sysctl(const  int  *name,  u_int	 namelen, void *oldp, size_t *oldlenp,
	   const void *newp, size_t newlen);

       int
       sysctlbyname(const   char   *name,   void   *oldp,   size_t   *oldlenp,
	   const void *newp, size_t newlen);

       int
       sysctlnametomib(const char *name, int *mibp, size_t *sizep);

DESCRIPTION
       The sysctl() function retrieves system information and allows processes
       with appropriate	privileges to set system information.  The information
       available from sysctl() consists	of integers, strings, and tables.  In-
       formation may be	retrieved and set from the command interface using the
       sysctl(8) utility.

       Unless  explicitly  noted below,	sysctl() returns a consistent snapshot
       of the data requested.  Consistency is obtained by locking the destina-
       tion buffer into	memory so that the data	 may  be  copied  out  without
       blocking.  Calls	to sysctl() are	serialized to avoid deadlock.

       The  state  is  described using a ``Management Information Base'' (MIB)
       style name, listed in name, which is a namelen length  array  of	 inte-
       gers.

       The sysctlbyname() function accepts an ASCII representation of the name
       and  internally	looks up the integer name vector.  Apart from that, it
       behaves the same	as the standard	sysctl() function.

       The information is copied into the buffer specified by oldp.  The  size
       of  the buffer is given by the location specified by oldlenp before the
       call, and that location gives the amount	of data	copied	after  a  suc-
       cessful	call and after a call that returns with	the error code ENOMEM.
       If the amount of	data available is greater than the size	of the	buffer
       supplied, the call supplies as much data	as fits	in the buffer provided
       and  returns  with  the error code ENOMEM.  If the old value is not de-
       sired, oldp and oldlenp should be set to	NULL.

       The size	of the available data can be determined	 by  calling  sysctl()
       with  the  NULL argument	for oldp.  The size of the available data will
       be returned in the location pointed to by  oldlenp.   For  some	opera-
       tions, the amount of space may change often.  For these operations, the
       system  attempts	 to round up so	that the returned size is large	enough
       for a call to return the	data shortly thereafter.

       To set a	new value, newp	is set to point	to a buffer of	length	newlen
       from  which  the	requested value	is to be taken.	 If a new value	is not
       to be set, newp should be set to	NULL and newlen	set to 0.

       The sysctlnametomib() function accepts an ASCII representation  of  the
       name,  looks up the integer name	vector,	and returns the	numeric	repre-
       sentation in the	mib array pointed to by	mibp.  The number of  elements
       in the mib array	is given by the	location specified by sizep before the
       call, and that location gives the number	of entries copied after	a suc-
       cessful	call.	The  resulting	mib and	size may be used in subsequent
       sysctl()	calls to get the data  associated  with	 the  requested	 ASCII
       name.   This interface is intended for use by applications that want to
       repeatedly request the same variable (the  sysctl()  function  runs  in
       about  a	third the time as the same request made	via the	sysctlbyname()
       function).  The sysctlnametomib() function is also useful for  fetching
       mib  prefixes and then adding a final component.	 For example, to fetch
       process information for processes with pid's less than 100:

	     int i, mib[4];
	     size_t len;
	     struct kinfo_proc kp;

	     /*	Fill out the first three components of the mib */
	     len = 4;
	     sysctlnametomib("kern.proc.pid", mib, &len);

	     /*	Fetch and print	entries	for pid's < 100	*/
	     for (i = 0; i < 100; i++) {
		     mib[3] = i;
		     len = sizeof(kp);
		     if	(sysctl(mib, 4,	&kp, &len, NULL, 0) == -1)
			     perror("sysctl");
		     else if (len > 0)
			     printkproc(&kp);
	     }

       The top level names are defined with a CTL_ prefix  in  <sys/sysctl.h>,
       and  are	 as follows.  The next and subsequent levels down are found in
       the include files listed	here, and described in separate	 sections  be-
       low.

	     Name	       Next Level Names		 Description
	     CTL_DEBUG	       <sys/sysctl.h>		 Debugging
	     CTL_VFS	       <sys/mount.h>		 File system
	     CTL_HW	       <sys/sysctl.h>		 Generic CPU, I/O
	     CTL_KERN	       <sys/sysctl.h>		 High kernel limits
	     CTL_MACHDEP       <sys/sysctl.h>		 Machine dependent
	     CTL_NET	       <sys/socket.h>		 Networking
	     CTL_USER	       <sys/sysctl.h>		 User-level
	     CTL_VM	       <vm/vm_param.h>		 Virtual memory

       For  example,  the  following retrieves the maximum number of processes
       allowed in the system:

	     int mib[2], maxproc;
	     size_t len;

	     mib[0] = CTL_KERN;
	     mib[1] = KERN_MAXPROC;
	     len = sizeof(maxproc);
	     sysctl(mib, 2, &maxproc, &len, NULL, 0);

       To retrieve the standard	search path for	the system utilities:

	     int mib[2];
	     size_t len;
	     char *p;

	     mib[0] = CTL_USER;
	     mib[1] = USER_CS_PATH;
	     sysctl(mib, 2, NULL, &len,	NULL, 0);
	     p = malloc(len);
	     sysctl(mib, 2, p, &len, NULL, 0);

   CTL_DEBUG
       The debugging variables vary from system	to system.  A debugging	 vari-
       able may	be added or deleted without need to recompile sysctl() to know
       about it.  Each time it runs, sysctl() gets the list of debugging vari-
       ables  from  the	 kernel	and displays their current values.  The	system
       defines	twenty	(struct	 ctldebug)  variables  named  debug0   through
       debug19.	  They	are declared as	separate variables so that they	can be
       individually initialized	at the location	of their associated  variable.
       The loader prevents multiple use	of the same variable by	issuing	errors
       if  a  variable is initialized in more than one place.  For example, to
       export the variable dospecialcheck as a debugging variable, the follow-
       ing declaration would be	used:

	     int dospecialcheck	= 1;
	     struct ctldebug debug5 = {	"dospecialcheck", &dospecialcheck };

   CTL_VFS
       A distinguished second level name, VFS_GENERIC, is used to get  general
       information about all file systems.  One	of its third level identifiers
       is VFS_MAXTYPENUM that gives the	highest	valid file system type number.
       Its other third level identifier	is VFS_CONF that returns configuration
       information  about the file system type given as	a fourth level identi-
       fier (see getvfsbyname(3) as an example of  its	use).	The  remaining
       second  level identifiers are the file system type number returned by a
       statfs(2) call or from VFS_CONF.	 The third level identifiers available
       for each	file system are	given in the  header  file  that  defines  the
       mount argument structure	for that file system.

   CTL_HW
       The  string  and	 integer information available for the CTL_HW level is
       detailed	below.	The changeable column shows whether a process with ap-
       propriate privilege may change the value.

	     Second Level Name	  Type		Changeable
	     HW_MACHINE		  string	no
	     HW_MODEL		  string	no
	     HW_NCPU		  integer	no
	     HW_BYTEORDER	  integer	no
	     HW_PHYSMEM		  integer	no
	     HW_USERMEM		  integer	no
	     HW_PAGESIZE	  integer	no
	     HW_FLOATINGPT	  integer	no
	     HW_MACHINE_ARCH	  string	no
	     HW_REALMEM		  integer	no
	     HW_AVAILPAGES	  integer	no

       HW_MACHINE
	       The machine class.

       HW_MODEL
	       The machine model

       HW_NCPU
	       The number of cpus.

       HW_BYTEORDER
	       The byteorder (4321 or 1234).

       HW_PHYSMEM
	       Amount of physical memory (in bytes), minus the amount used  by
	       the kernel, pre-loaded modules, and (on x86) the	dcons buffer.

       HW_USERMEM
	       Amount of memory	(in bytes) which is not	wired.

       HW_PAGESIZE
	       The software page size.

       HW_FLOATINGPT
	       Nonzero if the floating point support is	in hardware.

       HW_MACHINE_ARCH
	       The machine dependent architecture type.

       HW_REALMEM
	       Amount  of  memory  (in	bytes) reported	by the firmware.  That
	       value is	sometimes not sane; in that case, the  kernel  reports
	       the max memory address instead.

       HW_AVAILPAGES
	       The  same  value	 as  HW_PHYSMEM, measured in pages rather than
	       bytes.

   CTL_KERN
       The string and integer information available for	the CTL_KERN level  is
       detailed	below.	The changeable column shows whether a process with ap-
       propriate  privilege may	change the value.  The types of	data currently
       available are process information, system vnodes,  the  open  file  en-
       tries,  routing	table entries, virtual memory statistics, load average
       history,	and clock rate information.

	     Second Level Name		Type		       Changeable
	     KERN_ARGMAX		integer		       no
	     KERN_BOOTFILE		string		       yes
	     KERN_BOOTTIME		struct timeval	       no
	     KERN_CLOCKRATE		struct clockinfo       no
	     KERN_FILE			struct xfile	       no
	     KERN_HOSTID		integer		       yes
	     KERN_HOSTUUID		string		       yes
	     KERN_HOSTNAME		string		       yes
	     KERN_JOB_CONTROL		integer		       no
	     KERN_MAXFILES		integer		       yes
	     KERN_MAXFILESPERPROC	integer		       yes
	     KERN_MAXPROC		integer		       no
	     KERN_MAXPROCPERUID		integer		       yes
	     KERN_MAXVNODES		integer		       yes
	     KERN_NGROUPS		integer		       no
	     KERN_NISDOMAINNAME		string		       yes
	     KERN_OSRELDATE		integer		       no
	     KERN_OSRELEASE		string		       no
	     KERN_OSREV			integer		       no
	     KERN_OSTYPE		string		       no
	     KERN_POSIX1		integer		       no
	     KERN_PROC			node		       not applicable
	     KERN_QUANTUM		integer		       yes
	     KERN_SAVED_IDS		integer		       no
	     KERN_SECURELVL		integer		       raise only
	     KERN_UPDATEINTERVAL	integer		       no
	     KERN_VERSION		string		       no

       KERN_ARGMAX
	       The maximum bytes of argument to	execve(2).

       KERN_BOOTFILE
	       The full	pathname of the	file from which	the kernel was loaded.

       KERN_BOOTTIME
	       A struct	timeval	structure is returned.	 This  structure  con-
	       tains the time that the system was booted.

       KERN_CLOCKRATE
	       A  struct clockinfo structure is	returned.  This	structure con-
	       tains the clock,	statistics clock and profiling clock  frequen-
	       cies,  the  number  of  micro-seconds  per hz tick and the skew
	       rate.

       KERN_FILE
	       Return the entire file table.  The returned data	consists of an
	       array of	struct xfile, whose size depends on the	current	number
	       of such objects in the system.

       KERN_HOSTID
	       Get or set the host ID.

       KERN_HOSTUUID
	       Get or set the host's universally unique	identifier (UUID).

       KERN_HOSTNAME
	       Get or set the hostname.

       KERN_JOB_CONTROL
	       Return 1	if job control is available on this system,  otherwise
	       0.

       KERN_MAXFILES
	       The maximum number of files that	may be open in the system.

       KERN_MAXFILESPERPROC
	       The  maximum  number  of	 files	that  may be open for a	single
	       process.	 This limit only applies to processes with  an	effec-
	       tive  uid  of  nonzero  at the time of the open request.	 Files
	       that have already been opened are not affected if the limit  or
	       the effective uid is changed.

       KERN_MAXPROC
	       The  maximum number of concurrent processes the system will al-
	       low.

       KERN_MAXPROCPERUID
	       The maximum number of concurrent	processes the system will  al-
	       low  for	 a  single  effective uid.  This limit only applies to
	       processes with an effective uid of nonzero at  the  time	 of  a
	       fork request.  Processes	that have already been started are not
	       affected	if the limit is	changed.

       KERN_MAXVNODES
	       The maximum number of vnodes available on the system.

       KERN_NGROUPS
	       The maximum number of supplemental groups.

       KERN_NISDOMAINNAME
	       The name	of the current YP/NIS domain.

       KERN_OSRELDATE
	       The kernel release version in the format	MmmRxx,	where M	is the
	       major version, mm is the	two digit minor	version, R is 0	if re-
	       lease branch, otherwise 1, and xx is updated when the available
	       APIs change.

	       The  userland  release version is available from	<osreldate.h>;
	       parse this file if you need to get the release version  of  the
	       currently installed userland.

       KERN_OSRELEASE
	       The system release string.

       KERN_OSREV
	       The system revision string.

       KERN_OSTYPE
	       The system type string.

       KERN_POSIX1
	       The  version of IEEE Std	1003.1 ("POSIX.1") with	which the sys-
	       tem attempts to comply.

       KERN_PROC
	       Return selected information about specific running processes.

	       For the following names,	an array of struct  kinfo_proc	struc-
	       tures  is returned, whose size depends on the current number of
	       such objects in the system.

		     Third Level Name	       Fourth Level
		     KERN_PROC_ALL	       None
		     KERN_PROC_PID	       A process ID
		     KERN_PROC_PGRP	       A process group
		     KERN_PROC_TTY	       A tty device
		     KERN_PROC_UID	       A user ID
		     KERN_PROC_RUID	       A real user ID

	       If the third level name is KERN_PROC_ARGS then the command line
	       argument	array is returned in a flattened form, i.e., zero-ter-
	       minated arguments follow	each other.  The total size  of	 array
	       is  returned.  It is also possible for a	process	to set its own
	       process	title  this  way.   If	the  third   level   name   is
	       KERN_PROC_PATHNAME,  the	 path  of  the	process'  text file is
	       stored.	For KERN_PROC_PATHNAME,	a process ID of	-1 implies the
	       current process.

		     Third Level Name	       Fourth Level
		     KERN_PROC_ARGS	       A process ID
		     KERN_PROC_PATHNAME	       A process ID

       KERN_QUANTUM
	       The maximum period  of  time,  in  microseconds,	 for  which  a
	       process	is  allowed  to	 run  without being preempted if other
	       processes are in	the run	queue.

       KERN_SAVED_IDS
	       Returns 1 if saved set-group and	saved set-user	ID  is	avail-
	       able.

       KERN_SECURELVL
	       The  system  security  level.   This  level  may	 be  raised by
	       processes with appropriate privilege.  It may not be lowered.

       KERN_VERSION
	       The system version string.

   CTL_NET
       The string and integer information available for	the CTL_NET  level  is
       detailed	below.	The changeable column shows whether a process with ap-
       propriate privilege may change the value.

	     Second Level Name		Type		       Changeable
	     PF_ROUTE			routing	messages       no
	     PF_INET			IPv4 values	       yes
	     PF_INET6			IPv6 values	       yes

       PF_ROUTE
	       Return the entire routing table or a subset of it.  The data is
	       returned	 as  a	sequence of routing messages (see route(4) for
	       the header file,	format and meaning).  The length of each  mes-
	       sage is contained in the	message	header.

	       The  third  level name is a protocol number, which is currently
	       always 0.  The fourth level name	is an  address	family,	 which
	       may  be	set  to	 0 to select all address families.  The	fifth,
	       sixth, and seventh level	names are as follows:

		     Fifth level    Sixth Level	   Seventh Level
		     NET_RT_FLAGS   rtflags	   None
		     NET_RT_DUMP    None	   None	or fib number
		     NET_RT_IFLIST  0 or if_index  None
		     NET_RT_IFMALIST		   0 or	if_index    None
		     NET_RT_IFLISTL 0 or if_index  None
		     NET_RT_NHOPS   None	   fib number

	       The NET_RT_IFMALIST name	returns	 information  about  multicast
	       group  memberships  on all interfaces if	0 is specified,	or for
	       the interface specified by if_index.

	       The NET_RT_IFLISTL is like NET_RT_IFLIST, just  returning  mes-
	       sage  header structs with additional fields allowing the	inter-
	       face to be extended without breaking binary compatibility.  The
	       NET_RT_IFLISTL uses 'l' versions	of the message	header	struc-
	       tures: struct if_msghdrl	and struct ifa_msghdrl.

	       NET_RT_NHOPS  returns all nexthops for specified	address	family
	       in given	fib.

       PF_INET
	       Get or set various global information about the IPv4  (Internet
	       Protocol	 version  4).	The  third level name is the protocol.
	       The fourth level	name is	the variable name.  The	currently  de-
	       fined protocols and names are:

	       Protocol	     Variable	   Type	     Changeable
	       icmp	     bmcastecho	   integer   yes
	       icmp	     maskrepl	   integer   yes
	       ip	     forwarding	   integer   yes
	       ip	     redirect	   integer   yes
	       ip	     ttl	   integer   yes
	       udp	     checksum	   integer   yes

	       The variables are as follows:

	       icmp.bmcastecho
		       Returns	1  if  an  ICMP	echo request to	a broadcast or
		       multicast address is to be answered.

	       icmp.maskrepl
		       Returns 1 if ICMP network mask requests are to  be  an-
		       swered.

	       ip.forwarding
		       Returns	1  when	IP forwarding is enabled for the host,
		       meaning that the	host is	acting as a router.

	       ip.redirect
		       Returns 1 when ICMP redirects may be sent by the	 host.
		       This  option  is	 ignored unless	the host is routing IP
		       packets,	and should normally be enabled on all systems.

	       ip.ttl  The maximum time-to-live	(hop count) value  for	an  IP
		       packet  sourced	by  the	system.	 This value applies to
		       normal transport	protocols, not to ICMP.

	       udp.checksum
		       Returns 1 when UDP checksums  are  being	 computed  and
		       checked.	  Disabling UDP	checksums is strongly discour-
		       aged.

		       For  variables  net.inet.*.ipsec,   please   refer   to
		       ipsec(4).

       PF_INET6
	       Get  or set various global information about the	IPv6 (Internet
	       Protocol	version	6).  The third level  name  is	the  protocol.
	       The fourth level	name is	the variable name.

	       For  variables net.inet6.* please refer to inet6(4).  For vari-
	       ables net.inet6.*.ipsec6, please	refer to ipsec(4).

   CTL_USER
       The string and integer information available for	the CTL_USER level  is
       detailed	below.	The changeable column shows whether a process with ap-
       propriate privilege may change the value.

	     Second Level Name		 Type	       Changeable
	     USER_BC_BASE_MAX		 integer       no
	     USER_BC_DIM_MAX		 integer       no
	     USER_BC_SCALE_MAX		 integer       no
	     USER_BC_STRING_MAX		 integer       no
	     USER_COLL_WEIGHTS_MAX	 integer       no
	     USER_CS_PATH		 string	       no
	     USER_EXPR_NEST_MAX		 integer       no
	     USER_LINE_MAX		 integer       no
	     USER_LOCALBASE		 string	       no
	     USER_POSIX2_CHAR_TERM	 integer       no
	     USER_POSIX2_C_BIND		 integer       no
	     USER_POSIX2_C_DEV		 integer       no
	     USER_POSIX2_FORT_DEV	 integer       no
	     USER_POSIX2_FORT_RUN	 integer       no
	     USER_POSIX2_LOCALEDEF	 integer       no
	     USER_POSIX2_SW_DEV		 integer       no
	     USER_POSIX2_UPE		 integer       no
	     USER_POSIX2_VERSION	 integer       no
	     USER_RE_DUP_MAX		 integer       no
	     USER_STREAM_MAX		 integer       no
	     USER_TZNAME_MAX		 integer       no

       USER_BC_BASE_MAX
	       The maximum ibase/obase values in the bc(1) utility.

       USER_BC_DIM_MAX
	       The maximum array size in the bc(1) utility.

       USER_BC_SCALE_MAX
	       The maximum scale value in the bc(1) utility.

       USER_BC_STRING_MAX
	       The maximum string length in the	bc(1) utility.

       USER_COLL_WEIGHTS_MAX
	       The maximum number of weights that can be assigned to any entry
	       of the LC_COLLATE order keyword in the locale definition	file.

       USER_CS_PATH
	       Return a	value for the PATH environment variable	that finds all
	       the standard utilities.

       USER_EXPR_NEST_MAX
	       The  maximum  number  of	 expressions that can be nested	within
	       parenthesis by the expr(1) utility.

       USER_LINE_MAX
	       The maximum length in bytes of a	text-processing	utility's  in-
	       put line.

       USER_LOCALBASE
	       Return  the value of localbase that has been compiled into sys-
	       tem utilities that need to have access to resources provided by
	       a port or package.

       USER_POSIX2_CHAR_TERM
	       Return 1	if the system supports at least	one terminal type  ca-
	       pable   of   all	  operations  described	 in  IEEE  Std	1003.2
	       ("POSIX.2"), otherwise 0.

       USER_POSIX2_C_BIND
	       Return 1	if the system's	C-language development facilities sup-
	       port the	C-Language Bindings Option, otherwise 0.

       USER_POSIX2_C_DEV
	       Return 1	if the	system	supports  the  C-Language  Development
	       Utilities Option, otherwise 0.

       USER_POSIX2_FORT_DEV
	       Return  1 if the	system supports	the FORTRAN Development	Utili-
	       ties Option, otherwise 0.

       USER_POSIX2_FORT_RUN
	       Return 1	if the system supports the FORTRAN  Runtime  Utilities
	       Option, otherwise 0.

       USER_POSIX2_LOCALEDEF
	       Return 1	if the system supports the creation of locales,	other-
	       wise 0.

       USER_POSIX2_SW_DEV
	       Return 1	if the system supports the Software Development	Utili-
	       ties Option, otherwise 0.

       USER_POSIX2_UPE
	       Return  1 if the	system supports	the User Portability Utilities
	       Option, otherwise 0.

       USER_POSIX2_VERSION
	       The version of IEEE Std 1003.2 ("POSIX.2") with which the  sys-
	       tem attempts to comply.

       USER_RE_DUP_MAX
	       The maximum number of repeated occurrences of a regular expres-
	       sion permitted when using interval notation.

       USER_STREAM_MAX
	       The  minimum  maximum number of streams that a process may have
	       open at any one time.

       USER_TZNAME_MAX
	       The minimum maximum number of types supported for the name of a
	       timezone.

   CTL_VM
       The string and integer information available for	the  CTL_VM  level  is
       detailed	below.	The changeable column shows whether a process with ap-
       propriate privilege may change the value.

	     Second Level Name		Type		     Changeable
	     VM_LOADAVG			struct loadavg	     no
	     VM_TOTAL			struct vmtotal	     no
	     VM_SWAPPING_ENABLED	integer		     maybe
	     VM_V_FREE_MIN		integer		     yes
	     VM_V_FREE_RESERVED		integer		     yes
	     VM_V_FREE_TARGET		integer		     yes
	     VM_V_INACTIVE_TARGET	integer		     yes
	     VM_V_PAGEOUT_FREE_MIN	integer		     yes
	     VM_OVERCOMMIT		integer		     yes

       VM_LOADAVG
	       Return the load average history.	 The returned data consists of
	       a struct	loadavg.

       VM_TOTAL
	       Return the system wide virtual memory statistics.  The returned
	       data consists of	a struct vmtotal.

       VM_SWAPPING_ENABLED
	       1  if process swapping is enabled or 0 if disabled.  This vari-
	       able is permanently set to 0 if the kernel was built with swap-
	       ping disabled.

       VM_V_FREE_MIN
	       Minimum amount of memory	(cache memory plus  free  memory)  re-
	       quired  to be available before a	process	waiting	on memory will
	       be awakened.

       VM_V_FREE_RESERVED
	       Processes will awaken the pageout daemon	and wait for memory if
	       the number of free and cached pages drops below this value.

       VM_V_FREE_TARGET
	       The total amount	of free	memory (including cache	 memory)  that
	       the pageout daemon tries	to maintain.

       VM_V_INACTIVE_TARGET
	       The  desired  number  of	inactive pages that the	pageout	daemon
	       should achieve when it runs.  Inactive pages can	be quickly in-
	       serted into process address space when needed.

       VM_V_PAGEOUT_FREE_MIN
	       If the amount of	free and cache memory falls below this	value,
	       the pageout daemon will enter "memory conserving	mode" to avoid
	       deadlock.

       VM_OVERCOMMIT
	       Overcommit behaviour, as	described in tuning(7).

RETURN VALUES
       Upon  successful	 completion,  the  value  0 is returned; otherwise the
       value -1	is returned and	the global variable errno is set  to  indicate
       the error.

FILES
       <sys/sysctl.h>	     definitions  for  top  level  identifiers,	second
			     level kernel and hardware identifiers,  and  user
			     level identifiers
       <sys/socket.h>	     definitions for second level network identifiers
       <sys/gmon.h>	     definitions for third level profiling identifiers
       <vm/vm_param.h>	     definitions for second level virtual memory iden-
			     tifiers
       <netinet/in.h>	     definitions for third level IPv4/IPv6 identifiers
			     and fourth	level IPv4/v6 identifiers
       <netinet/icmp_var.h>  definitions for fourth level ICMP identifiers
       <netinet/icmp6.h>     definitions for fourth level ICMPv6 identifiers
       <netinet/udp_var.h>   definitions for fourth level UDP identifiers

ERRORS
       The following errors may	be reported:

       [EFAULT]		  The  buffer  name,  oldp,  newp,  or	length pointer
			  oldlenp contains an invalid address.

       [EINVAL]		  The name array is less  than	two  or	 greater  than
			  CTL_MAXNAME.

       [EINVAL]		  A non-null newp is given and its specified length in
			  newlen is too	large or too small.

       [ENOMEM]		  The  length  pointed	to  by oldlenp is too short to
			  hold the requested value.

       [ENOMEM]		  The smaller of  either  the  length  pointed	to  by
			  oldlenp  or  the estimated size of the returned data
			  exceeds the system limit on locked memory.

       [ENOMEM]		  Locking the buffer oldp, or a	portion	of the	buffer
			  if  the estimated size of the	data to	be returned is
			  smaller, would cause the process to exceed its  per-
			  process locked memory	limit.

       [ENOTDIR]	  The name array specifies an intermediate rather than
			  terminal name.

       [EISDIR]		  The  name  array  specifies a	terminal name, but the
			  actual name is not terminal.

       [ENOENT]		  The name array specifies a value that	is unknown.

       [EPERM]		  An attempt is	made to	set a read-only	value.

       [EPERM]		  A process without appropriate	privilege attempts  to
			  set a	value.

SEE ALSO
       confstr(3), kvm(3), sysconf(3), sysctl(8)

HISTORY
       The sysctl() function first appeared in 4.4BSD.

FreeBSD	13.2			March 16, 2023			     SYSCTL(3)

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUES | FILES | ERRORS | SEE ALSO | HISTORY

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