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SYSCTL(3)		 BSD Library Functions Manual		     SYSCTL(3)

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

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <sys/types.h>
     #include <sys/sysctl.h>

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

     int
     sysctlbyname(const char *name, void *oldp, size_t *oldlenp, 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.
     Information 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 destination
     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 integers.

     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 successful 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 desired, 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 operations, 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 represen‐
     tation 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 repeat‐
     edly 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 infor‐
     mation 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 below.

	   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 variable
     may be added or deleted without need to recompile sysctl() to know about
     it.  Each time it runs, sysctl() gets the list of debugging variables
     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 ini‐
     tialized at the location of their associated variable.  The loader pre‐
     vents multiple use of the same variable by issuing errors if a variable
     is initialized in more than one place.  For example, to export the vari‐
     able dospecialcheck as a debugging variable, the following 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 identifier
     (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
     appropriate 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_MACHINE
	     The machine class.

     HW_MODEL
	     The machine model

     HW_NCPU
	     The number of cpus.

     HW_BYTEORDER
	     The byteorder (4,321, or 1,234).

     HW_PHYSMEM
	     The bytes of physical memory.

     HW_USERMEM
	     The bytes of non-kernel memory.

     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
	     The bytes of real memory.

   CTL_KERN
     The string and integer information available for the CTL_KERN level is
     detailed below.  The changeable column shows whether a process with
     appropriate privilege may change the value.  The types of data currently
     available are process information, system vnodes, the open file entries,
     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_PROF		      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_VNODE		      struct xvnode	     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 contains
	     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 effective
	     uid of nonzero at the time of the open request.  Files that have
	     already been opened are not affected if the limit or the effec‐
	     tive uid is changed.

     KERN_MAXPROC
	     The maximum number of concurrent processes the system will allow.

     KERN_MAXPROCPERUID
	     The maximum number of concurrent processes the system will allow
	     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
	     release 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 system
	     attempts to comply.

     KERN_PROC
	     Return selected information about specific running processes.

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

		   Third level name	     Fourth level is:
		   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-termi‐
	     nated 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 is:
		   KERN_PROC_ARGS	     A process ID
		   KERN_PROC_PATHNAME	     A process ID

     KERN_PROF
	     Return profiling information about the kernel.  If the kernel is
	     not compiled for profiling, attempts to retrieve any of the
	     KERN_PROF values will fail with ENOENT.  The third level names
	     for the string and integer profiling information is detailed
	     below.  The changeable column shows whether a process with appro‐
	     priate privilege may change the value.

		   Third level name	 Type			Changeable
		   GPROF_STATE		 integer		yes
		   GPROF_COUNT		 u_short[]		yes
		   GPROF_FROMS		 u_short[]		yes
		   GPROF_TOS		 struct tostruct	yes
		   GPROF_GMONPARAM	 struct gmonparam	no

	     The variables are as follows:

	     GPROF_STATE
		     Returns GMON_PROF_ON or GMON_PROF_OFF to show that pro‐
		     filing is running or stopped.

	     GPROF_COUNT
		     Array of statistical program counter counts.

	     GPROF_FROMS
		     Array indexed by program counter of call-from points.

	     GPROF_TOS
		     Array of struct tostruct describing destination of calls
		     and their counts.

	     GPROF_GMONPARAM
		     Structure giving the sizes of the above arrays.

     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 available.

     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.

     KERN_VNODE
	     Return the entire vnode table.  Note, the vnode table is not nec‐
	     essarily a consistent snapshot of the system.  The returned data
	     consists of an array whose size depends on the current number of
	     such objects in the system.  Each element of the array consists
	     of a struct xvnode.

   CTL_NET
     The string and integer information available for the CTL_NET level is
     detailed below.  The changeable column shows whether a process with
     appropriate 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 message 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 and sixth
	     level names are as follows:

		   Fifth level name	     Sixth level is:
		   NET_RT_FLAGS		     rtflags
		   NET_RT_DUMP		     None
		   NET_RT_IFLIST	     0 or if_index
		   NET_RT_IFMALIST	     0 or if_index

	     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.

     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 defined
	     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 mul‐
		     ticast address is to be answered.

	     icmp.maskrepl
		     Returns 1 if ICMP network mask requests are to be
		     answered.

	     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 nor‐
		     mal 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
     appropriate 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_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 input
	     line.

     USER_POSIX2_CHAR_TERM
	     Return 1 if the system supports at least one terminal type capa‐
	     ble 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 Utili‐
	     ties Option, otherwise 0.

     USER_POSIX2_FORT_DEV
	     Return 1 if the system supports the FORTRAN Development Utilities
	     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 system
	     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
     appropriate privilege may change the value.

	   Second level name	      Type		   Changeable
	   VM_LOADAVG		      struct loadavg	   no
	   VM_TOTAL		      struct vmtotal	   no
	   VM_PAGEOUT_ALGORITHM	      integer		   yes
	   VM_SWAPPING_ENABLED	      integer		   maybe
	   VM_V_CACHE_MAX	      integer		   yes
	   VM_V_CACHE_MIN	      integer		   yes
	   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_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_PAGEOUT_ALGORITHM
	     0 if the statistics-based page management algorithm is in use or
	     1 if the near-LRU algorithm is in use.

     VM_SWAPPING_ENABLED
	     1 if process swapping is enabled or 0 if disabled.	 This variable
	     is permanently set to 0 if the kernel was built with swapping
	     disabled.

     VM_V_CACHE_MAX
	     Maximum desired size of the cache queue.

     VM_V_CACHE_MIN
	     Minimum desired size of the cache queue.  If the cache queue size
	     falls very far below this value, the pageout daemon is awakened.

     VM_V_FREE_MIN
	     Minimum amount of memory (cache memory plus free memory) required
	     to be available before a process waiting on memory will be awak‐
	     ened.

     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
	     inserted 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.

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 identi‐
			   fiers
     <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.

BSD				April 25, 2010				   BSD
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