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28 .\" @(#)sysctl.3 8.4 (Berkeley) 5/9/95
38 .Nd get or set system information
45 .Fn sysctl "const int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen"
47 .Fn sysctlbyname "const char *name" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen"
49 .Fn sysctlnametomib "const char *name" "int *mibp" "size_t *sizep"
53 function retrieves system information and allows processes with
54 appropriate privileges to set system information.
55 The information available from
57 consists of integers, strings, and tables.
58 Information may be retrieved and set from the command interface
63 Unless explicitly noted below,
65 returns a consistent snapshot of the data requested.
66 Consistency is obtained by locking the destination
67 buffer into memory so that the data may be copied out without blocking.
70 are serialized to avoid deadlock.
72 The state is described using a ``Management Information Base'' (MIB)
77 length array of integers.
81 function accepts an ASCII representation of the name and internally
82 looks up the integer name vector.
83 Apart from that, it behaves the same
88 The information is copied into the buffer specified by
90 The size of the buffer is given by the location specified by
93 and that location gives the amount of data copied after a successful call
94 and after a call that returns with the error code
96 If the amount of data available is greater
97 than the size of the buffer supplied,
98 the call supplies as much data as fits in the buffer provided
99 and returns with the error code
101 If the old value is not desired,
105 should be set to NULL.
107 The size of the available data can be determined by calling
113 The size of the available data will be returned in the location pointed to by
115 For some operations, the amount of space may change often.
116 For these operations,
117 the system attempts to round up so that the returned size is
118 large enough for a call to return the data shortly thereafter.
122 is set to point to a buffer of length
124 from which the requested value is to be taken.
125 If a new value is not to be set,
127 should be set to NULL and
133 function accepts an ASCII representation of the name,
134 looks up the integer name vector,
135 and returns the numeric representation in the mib array pointed to by
137 The number of elements in the mib array is given by the location specified by
140 and that location gives the number of entries copied after a successful call.
145 may be used in subsequent
147 calls to get the data associated with the requested ASCII name.
148 This interface is intended for use by applications that want to
149 repeatedly request the same variable (the
151 function runs in about a third the time as the same request made via the
156 function is also useful for fetching mib prefixes and then adding
158 For example, to fetch process information
159 for processes with pid's less than 100:
161 .Bd -literal -offset indent -compact
164 struct kinfo_proc kp;
166 /* Fill out the first three components of the mib */
168 sysctlnametomib("kern.proc.pid", mib, &len);
170 /* Fetch and print entries for pid's < 100 */
171 for (i = 0; i < 100; i++) {
174 if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1)
181 The top level names are defined with a CTL_ prefix in
184 The next and subsequent levels down are found in the include files
185 listed here, and described in separate sections below.
186 .Bl -column CTLXMACHDEPXXX "Next Level NamesXXXXXX" -offset indent
187 .It Sy Name Ta Sy Next Level Names Ta Sy Description
188 .It Dv CTL_DEBUG Ta In sys/sysctl.h Ta Debugging
189 .It Dv CTL_VFS Ta In sys/mount.h Ta File system
190 .It Dv CTL_HW Ta In sys/sysctl.h Ta Generic CPU, I/O
191 .It Dv CTL_KERN Ta In sys/sysctl.h Ta High kernel limits
192 .It Dv CTL_MACHDEP Ta In sys/sysctl.h Ta Machine dependent
193 .It Dv CTL_NET Ta In sys/socket.h Ta Networking
194 .It Dv CTL_USER Ta In sys/sysctl.h Ta User-level
195 .It Dv CTL_VM Ta In vm/vm_param.h Ta Virtual memory
198 For example, the following retrieves the maximum number of processes allowed
201 .Bd -literal -offset indent -compact
206 mib[1] = KERN_MAXPROC;
207 len = sizeof(maxproc);
208 sysctl(mib, 2, &maxproc, &len, NULL, 0);
211 To retrieve the standard search path for the system utilities:
213 .Bd -literal -offset indent -compact
219 mib[1] = USER_CS_PATH;
220 sysctl(mib, 2, NULL, &len, NULL, 0);
222 sysctl(mib, 2, p, &len, NULL, 0);
225 The debugging variables vary from system to system.
226 A debugging variable may be added or deleted without need to recompile
231 gets the list of debugging variables from the kernel and
232 displays their current values.
233 The system defines twenty
234 .Pq Vt "struct ctldebug"
239 They are declared as separate variables so that they can be
240 individually initialized at the location of their associated variable.
241 The loader prevents multiple use of the same variable by issuing errors
242 if a variable is initialized in more than one place.
243 For example, to export the variable
245 as a debugging variable, the following declaration would be used:
247 .Bd -literal -offset indent -compact
248 int dospecialcheck = 1;
249 struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck };
252 A distinguished second level name, VFS_GENERIC,
253 is used to get general information about all file systems.
254 One of its third level identifiers is VFS_MAXTYPENUM
255 that gives the highest valid file system type number.
256 Its other third level identifier is VFS_CONF that
257 returns configuration information about the file system
258 type given as a fourth level identifier (see
260 as an example of its use).
261 The remaining second level identifiers are the
262 file system type number returned by a
264 call or from VFS_CONF.
265 The third level identifiers available for each file system
266 are given in the header file that defines the mount
267 argument structure for that file system.
269 The string and integer information available for the CTL_HW level
271 The changeable column shows whether a process with appropriate
272 privilege may change the value.
273 .Bl -column "Second Level Name" integerXXX Changeable -offset indent
274 .It Sy Second Level Name Ta Sy Type Ta Sy Changeable
275 .It Dv HW_MACHINE Ta string Ta no
276 .It Dv HW_MODEL Ta string Ta no
277 .It Dv HW_NCPU Ta integer Ta no
278 .It Dv HW_BYTEORDER Ta integer Ta no
279 .It Dv HW_PHYSMEM Ta integer Ta no
280 .It Dv HW_USERMEM Ta integer Ta no
281 .It Dv HW_PAGESIZE Ta integer Ta no
282 .\".It Dv HW_DISKNAMES Ta integer Ta no
283 .\".It Dv HW_DISKSTATS Ta integer Ta no
284 .It Dv HW_FLOATINGPT Ta integer Ta no
285 .It Dv HW_MACHINE_ARCH Ta string Ta no
286 .It Dv HW_REALMEM Ta integer Ta no
287 .It Dv HW_AVAILPAGES Ta integer Ta no
297 The byteorder (4321 or 1234).
299 Amount of physical memory (in bytes), minus the amount used by the kernel,
300 pre-loaded modules, and (on x86) the dcons buffer.
302 Amount of memory (in bytes) which is not wired.
304 The software page size.
305 .\".It Fa HW_DISKNAMES
306 .\".It Fa HW_DISKSTATS
308 Nonzero if the floating point support is in hardware.
309 .It Li HW_MACHINE_ARCH
310 The machine dependent architecture type.
312 Amount of memory (in bytes) reported by the firmware.
313 That value is sometimes not sane; in that case, the kernel reports the max
314 memory address instead.
318 measured in pages rather than bytes.
321 The string and integer information available for the CTL_KERN level
323 The changeable column shows whether a process with appropriate
324 privilege may change the value.
325 The types of data currently available are process information,
326 system vnodes, the open file entries, routing table entries,
327 virtual memory statistics, load average history, and clock rate
329 .Bl -column "KERNXMAXFILESPERPROCXXX" "struct clockrateXXX" -offset indent
330 .It Sy Second Level Name Ta Sy Type Ta Sy Changeable
331 .It Dv KERN_ARGMAX Ta integer Ta no
332 .It Dv KERN_BOOTFILE Ta string Ta yes
333 .It Dv KERN_BOOTTIME Ta struct timeval Ta no
334 .It Dv KERN_CLOCKRATE Ta struct clockinfo Ta no
335 .It Dv KERN_FILE Ta struct xfile Ta no
336 .It Dv KERN_HOSTID Ta integer Ta yes
337 .It Dv KERN_HOSTUUID Ta string Ta yes
338 .It Dv KERN_HOSTNAME Ta string Ta yes
339 .It Dv KERN_JOB_CONTROL Ta integer Ta no
340 .It Dv KERN_MAXFILES Ta integer Ta yes
341 .It Dv KERN_MAXFILESPERPROC Ta integer Ta yes
342 .It Dv KERN_MAXPROC Ta integer Ta no
343 .It Dv KERN_MAXPROCPERUID Ta integer Ta yes
344 .It Dv KERN_MAXVNODES Ta integer Ta yes
345 .It Dv KERN_NGROUPS Ta integer Ta no
346 .It Dv KERN_NISDOMAINNAME Ta string Ta yes
347 .It Dv KERN_OSRELDATE Ta integer Ta no
348 .It Dv KERN_OSRELEASE Ta string Ta no
349 .It Dv KERN_OSREV Ta integer Ta no
350 .It Dv KERN_OSTYPE Ta string Ta no
351 .It Dv KERN_POSIX1 Ta integer Ta no
352 .It Dv KERN_PROC Ta node Ta not applicable
353 .It Dv KERN_PROF Ta node Ta not applicable
354 .It Dv KERN_QUANTUM Ta integer Ta yes
355 .It Dv KERN_SAVED_IDS Ta integer Ta no
356 .It Dv KERN_SECURELVL Ta integer Ta raise only
357 .It Dv KERN_UPDATEINTERVAL Ta integer Ta no
358 .It Dv KERN_VERSION Ta string Ta no
359 .It Dv KERN_VNODE Ta struct xvnode Ta no
363 The maximum bytes of argument to
366 The full pathname of the file from which the kernel was loaded.
370 structure is returned.
371 This structure contains the time that the system was booted.
372 .It Li KERN_CLOCKRATE
375 structure is returned.
376 This structure contains the clock, statistics clock and profiling clock
377 frequencies, the number of micro-seconds per hz tick and the skew rate.
379 Return the entire file table.
380 The returned data consists of an array of
382 whose size depends on the current number of such objects in the system.
384 Get or set the host ID.
386 Get or set the host's universally unique identifier (UUID).
388 Get or set the hostname.
389 .It Li KERN_JOB_CONTROL
390 Return 1 if job control is available on this system, otherwise 0.
392 The maximum number of files that may be open in the system.
393 .It Li KERN_MAXFILESPERPROC
394 The maximum number of files that may be open for a single process.
395 This limit only applies to processes with an effective uid of nonzero
396 at the time of the open request.
397 Files that have already been opened are not affected if the limit
398 or the effective uid is changed.
400 The maximum number of concurrent processes the system will allow.
401 .It Li KERN_MAXPROCPERUID
402 The maximum number of concurrent processes the system will allow
403 for a single effective uid.
404 This limit only applies to processes with an effective uid of nonzero
405 at the time of a fork request.
406 Processes that have already been started are not affected if the limit
408 .It Li KERN_MAXVNODES
409 The maximum number of vnodes available on the system.
411 The maximum number of supplemental groups.
412 .It Li KERN_NISDOMAINNAME
413 The name of the current YP/NIS domain.
414 .It Li KERN_OSRELDATE
415 The kernel release version in the format
416 .Ar M Ns Ar mm Ns Ar R Ns Ar xx ,
419 is the major version,
421 is the two digit minor version,
423 is 0 if release branch, otherwise 1,
426 is updated when the available APIs change.
428 The userland release version is available from
430 parse this file if you need to get the release version of
431 the currently installed userland.
432 .It Li KERN_OSRELEASE
433 The system release string.
435 The system revision string.
437 The system type string.
441 with which the system
444 Return selected information about specific running processes.
446 For the following names, an array of
447 .Va struct kinfo_proc
448 structures is returned,
449 whose size depends on the current number of such objects in the system.
450 .Bl -column "Third Level NameXXXXXX" "Fourth LevelXXXXXX" -offset indent
451 .It Sy Third Level Name Ta Sy Fourth Level
452 .It Dv KERN_PROC_ALL Ta None
453 .It Dv KERN_PROC_PID Ta A process ID
454 .It Dv KERN_PROC_PGRP Ta A process group
455 .It Dv KERN_PROC_TTY Ta A tty device
456 .It Dv KERN_PROC_UID Ta A user ID
457 .It Dv KERN_PROC_RUID Ta A real user ID
460 If the third level name is
462 then the command line argument
463 array is returned in a flattened form, i.e., zero-terminated arguments
465 The total size of array is returned.
466 It is also possible for a process to set its own process title this way.
467 If the third level name is
468 .Dv KERN_PROC_PATHNAME ,
470 process' text file is stored.
472 .Dv KERN_PROC_PATHNAME ,
475 implies the current process.
476 .Bl -column "Third Level NameXXXXXX" "Fourth LevelXXXXXX" -offset indent
477 .It Sy Third Level Name Ta Sy Fourth Level
478 .It Dv KERN_PROC_ARGS Ta "A process ID"
479 .It Dv KERN_PROC_PATHNAME Ta "A process ID"
482 Return profiling information about the kernel.
483 If the kernel is not compiled for profiling,
484 attempts to retrieve any of the KERN_PROF values will
487 The third level names for the string and integer profiling information
489 The changeable column shows whether a process with appropriate
490 privilege may change the value.
491 .Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent
492 .It Sy Third Level Name Ta Sy Type Ta Sy Changeable
493 .It Dv GPROF_STATE Ta integer Ta yes
494 .It Dv GPROF_COUNT Ta u_short[\|] Ta yes
495 .It Dv GPROF_FROMS Ta u_short[\|] Ta yes
496 .It Dv GPROF_TOS Ta struct tostruct Ta yes
497 .It Dv GPROF_GMONPARAM Ta struct gmonparam Ta no
500 The variables are as follows:
503 Returns GMON_PROF_ON or GMON_PROF_OFF to show that profiling
504 is running or stopped.
506 Array of statistical program counter counts.
508 Array indexed by program counter of call-from points.
512 describing destination of calls and their counts.
513 .It Li GPROF_GMONPARAM
514 Structure giving the sizes of the above arrays.
517 The maximum period of time, in microseconds, for which a process is allowed
518 to run without being preempted if other processes are in the run queue.
519 .It Li KERN_SAVED_IDS
520 Returns 1 if saved set-group and saved set-user ID is available.
521 .It Li KERN_SECURELVL
522 The system security level.
523 This level may be raised by processes with appropriate privilege.
524 It may not be lowered.
526 The system version string.
528 Return the entire vnode table.
529 Note, the vnode table is not necessarily a consistent snapshot of
531 The returned data consists of an array whose size depends on the
532 current number of such objects in the system.
533 Each element of the array consists of a
537 The string and integer information available for the CTL_NET level
539 The changeable column shows whether a process with appropriate
540 privilege may change the value.
541 .Bl -column "Second Level NameXXXXXX" "routing messagesXXX" -offset indent
542 .It Sy Second Level Name Ta Sy Type Ta Sy Changeable
543 .It Dv PF_ROUTE Ta routing messages Ta no
544 .It Dv PF_INET Ta IPv4 values Ta yes
545 .It Dv PF_INET6 Ta IPv6 values Ta yes
549 Return the entire routing table or a subset of it.
550 The data is returned as a sequence of routing messages (see
552 for the header file, format and meaning).
553 The length of each message is contained in the message header.
555 The third level name is a protocol number, which is currently always 0.
556 The fourth level name is an address family, which may be set to 0 to
557 select all address families.
558 The fifth, sixth, and seventh level names are as follows:
559 .Bl -column -offset indent "Fifth Level" "Sixth Level" "Seventh Level"
560 .It Sy Fifth level Ta Sy Sixth Level Ta Sy Seventh Level
561 .It Dv NET_RT_FLAGS Ta rtflags Ta None
562 .It Dv NET_RT_DUMP Ta None Ta None or fib number
563 .It Dv NET_RT_IFLIST Ta 0 or if_index Ta None
564 .It Dv NET_RT_IFMALIST Ta 0 or if_index Ta None
565 .It Dv NET_RT_IFLISTL Ta 0 or if_index Ta None
570 name returns information about multicast group memberships on all interfaces
571 if 0 is specified, or for the interface specified by
578 just returning message header structs with additional fields allowing the
579 interface to be extended without breaking binary compatibility.
582 uses 'l' versions of the message header structures:
583 .Va struct if_msghdrl
585 .Va struct ifa_msghdrl .
587 Get or set various global information about the IPv4
588 (Internet Protocol version 4).
589 The third level name is the protocol.
590 The fourth level name is the variable name.
591 The currently defined protocols and names are:
592 .Bl -column ProtocolXX VariableXX TypeXX ChangeableXX
593 .It Sy Protocol Ta Sy Variable Ta Sy Type Ta Sy Changeable
594 .It icmp Ta bmcastecho Ta integer Ta yes
595 .It icmp Ta maskrepl Ta integer Ta yes
596 .It ip Ta forwarding Ta integer Ta yes
597 .It ip Ta redirect Ta integer Ta yes
598 .It ip Ta ttl Ta integer Ta yes
599 .It udp Ta checksum Ta integer Ta yes
602 The variables are as follows:
604 .It Li icmp.bmcastecho
605 Returns 1 if an ICMP echo request to a broadcast or multicast address is
608 Returns 1 if ICMP network mask requests are to be answered.
610 Returns 1 when IP forwarding is enabled for the host,
611 meaning that the host is acting as a router.
613 Returns 1 when ICMP redirects may be sent by the host.
614 This option is ignored unless the host is routing IP packets,
615 and should normally be enabled on all systems.
617 The maximum time-to-live (hop count) value for an IP packet sourced by
619 This value applies to normal transport protocols, not to ICMP.
621 Returns 1 when UDP checksums are being computed and checked.
622 Disabling UDP checksums is strongly discouraged.
624 For variables net.inet.*.ipsec, please refer to
628 Get or set various global information about the IPv6
629 (Internet Protocol version 6).
630 The third level name is the protocol.
631 The fourth level name is the variable name.
633 For variables net.inet6.* please refer to
635 For variables net.inet6.*.ipsec6, please refer to
639 The string and integer information available for the CTL_USER level
641 The changeable column shows whether a process with appropriate
642 privilege may change the value.
643 .Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent
644 .It Sy Second Level Name Ta Sy Type Ta Sy Changeable
645 .It Dv USER_BC_BASE_MAX Ta integer Ta no
646 .It Dv USER_BC_DIM_MAX Ta integer Ta no
647 .It Dv USER_BC_SCALE_MAX Ta integer Ta no
648 .It Dv USER_BC_STRING_MAX Ta integer Ta no
649 .It Dv USER_COLL_WEIGHTS_MAX Ta integer Ta no
650 .It Dv USER_CS_PATH Ta string Ta no
651 .It Dv USER_EXPR_NEST_MAX Ta integer Ta no
652 .It Dv USER_LINE_MAX Ta integer Ta no
653 .It Dv USER_POSIX2_CHAR_TERM Ta integer Ta no
654 .It Dv USER_POSIX2_C_BIND Ta integer Ta no
655 .It Dv USER_POSIX2_C_DEV Ta integer Ta no
656 .It Dv USER_POSIX2_FORT_DEV Ta integer Ta no
657 .It Dv USER_POSIX2_FORT_RUN Ta integer Ta no
658 .It Dv USER_POSIX2_LOCALEDEF Ta integer Ta no
659 .It Dv USER_POSIX2_SW_DEV Ta integer Ta no
660 .It Dv USER_POSIX2_UPE Ta integer Ta no
661 .It Dv USER_POSIX2_VERSION Ta integer Ta no
662 .It Dv USER_RE_DUP_MAX Ta integer Ta no
663 .It Dv USER_STREAM_MAX Ta integer Ta no
664 .It Dv USER_TZNAME_MAX Ta integer Ta no
667 .It Li USER_BC_BASE_MAX
668 The maximum ibase/obase values in the
671 .It Li USER_BC_DIM_MAX
672 The maximum array size in the
675 .It Li USER_BC_SCALE_MAX
676 The maximum scale value in the
679 .It Li USER_BC_STRING_MAX
680 The maximum string length in the
683 .It Li USER_COLL_WEIGHTS_MAX
684 The maximum number of weights that can be assigned to any entry of
685 the LC_COLLATE order keyword in the locale definition file.
687 Return a value for the
689 environment variable that finds all the standard utilities.
690 .It Li USER_EXPR_NEST_MAX
691 The maximum number of expressions that can be nested within
696 The maximum length in bytes of a text-processing utility's input
698 .It Li USER_POSIX2_CHAR_TERM
699 Return 1 if the system supports at least one terminal type capable of
700 all operations described in
703 .It Li USER_POSIX2_C_BIND
704 Return 1 if the system's C-language development facilities support the
705 C-Language Bindings Option, otherwise 0.
706 .It Li USER_POSIX2_C_DEV
707 Return 1 if the system supports the C-Language Development Utilities Option,
709 .It Li USER_POSIX2_FORT_DEV
710 Return 1 if the system supports the FORTRAN Development Utilities Option,
712 .It Li USER_POSIX2_FORT_RUN
713 Return 1 if the system supports the FORTRAN Runtime Utilities Option,
715 .It Li USER_POSIX2_LOCALEDEF
716 Return 1 if the system supports the creation of locales, otherwise 0.
717 .It Li USER_POSIX2_SW_DEV
718 Return 1 if the system supports the Software Development Utilities Option,
720 .It Li USER_POSIX2_UPE
721 Return 1 if the system supports the User Portability Utilities Option,
723 .It Li USER_POSIX2_VERSION
726 with which the system attempts to comply.
727 .It Li USER_RE_DUP_MAX
728 The maximum number of repeated occurrences of a regular expression
729 permitted when using interval notation.
730 .It Li USER_STREAM_MAX
731 The minimum maximum number of streams that a process may have open
733 .It Li USER_TZNAME_MAX
734 The minimum maximum number of types supported for the name of a
738 The string and integer information available for the CTL_VM level
740 The changeable column shows whether a process with appropriate
741 privilege may change the value.
742 .Bl -column "Second Level NameXXXXXX" "struct loadavgXXX" -offset indent
743 .It Sy Second Level Name Ta Sy Type Ta Sy Changeable
744 .It Dv VM_LOADAVG Ta struct loadavg Ta no
745 .It Dv VM_TOTAL Ta struct vmtotal Ta no
746 .It Dv VM_SWAPPING_ENABLED Ta integer Ta maybe
747 .It Dv VM_V_FREE_MIN Ta integer Ta yes
748 .It Dv VM_V_FREE_RESERVED Ta integer Ta yes
749 .It Dv VM_V_FREE_TARGET Ta integer Ta yes
750 .It Dv VM_V_INACTIVE_TARGET Ta integer Ta yes
751 .It Dv VM_V_PAGEOUT_FREE_MIN Ta integer Ta yes
752 .It Dv VM_OVERCOMMIT Ta integer Ta yes
756 Return the load average history.
757 The returned data consists of a
760 Return the system wide virtual memory statistics.
761 The returned data consists of a
763 .It Li VM_SWAPPING_ENABLED
764 1 if process swapping is enabled or 0 if disabled.
766 permanently set to 0 if the kernel was built with swapping disabled.
768 Minimum amount of memory (cache memory plus free memory)
769 required to be available before a process waiting on memory will be
771 .It Li VM_V_FREE_RESERVED
772 Processes will awaken the pageout daemon and wait for memory if the
773 number of free and cached pages drops below this value.
774 .It Li VM_V_FREE_TARGET
775 The total amount of free memory (including cache memory) that the
776 pageout daemon tries to maintain.
777 .It Li VM_V_INACTIVE_TARGET
778 The desired number of inactive pages that the pageout daemon should
779 achieve when it runs.
780 Inactive pages can be quickly inserted into
781 process address space when needed.
782 .It Li VM_V_PAGEOUT_FREE_MIN
783 If the amount of free and cache memory falls below this value, the
784 pageout daemon will enter "memory conserving mode" to avoid deadlock.
786 Overcommit behaviour, as described in
792 .Bl -tag -width <netinet/icmpXvar.h> -compact
794 definitions for top level identifiers, second level kernel and hardware
795 identifiers, and user level identifiers
797 definitions for second level network identifiers
799 definitions for third level profiling identifiers
801 definitions for second level virtual memory identifiers
803 definitions for third level IPv4/IPv6 identifiers and
804 fourth level IPv4/v6 identifiers
805 .It In netinet/icmp_var.h
806 definitions for fourth level ICMP identifiers
807 .It In netinet/icmp6.h
808 definitions for fourth level ICMPv6 identifiers
809 .It In netinet/udp_var.h
810 definitions for fourth level UDP identifiers
813 The following errors may be reported:
822 contains an invalid address.
826 array is less than two or greater than CTL_MAXNAME.
830 is given and its specified length in
832 is too large or too small.
834 The length pointed to by
836 is too short to hold the requested value.
838 The smaller of either the length pointed to by
840 or the estimated size of the returned data exceeds the
841 system limit on locked memory.
845 or a portion of the buffer if the estimated size of the data
846 to be returned is smaller,
847 would cause the process to exceed its per-process locked memory limit.
851 array specifies an intermediate rather than terminal name.
855 array specifies a terminal name, but the actual name is not terminal.
859 array specifies a value that is unknown.
861 An attempt is made to set a read-only value.
863 A process without appropriate privilege attempts to set a value.
873 function first appeared in