gen/FreeBSD/sysctl.3

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  28 .\"     @(#)sysctl.3    8.4 (Berkeley) 5/9/95
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  31 .Dd May 17, 2013
  32 .Dt SYSCTL 3
  33 .Os
  34 .Sh NAME
  35 .Nm sysctl ,
  36 .Nm sysctlbyname ,
  37 .Nm sysctlnametomib
  38 .Nd get or set system information
  39 .Sh LIBRARY
  40 .Lb libc
  41 .Sh SYNOPSIS
  42 .In sys/types.h
  43 .In sys/sysctl.h
  44 .Ft int
  45 .Fn sysctl "int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen"
  46 .Ft int
  47 .Fn sysctlbyname "const char *name" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen"
  48 .Ft int
  49 .Fn sysctlnametomib "const char *name" "int *mibp" "size_t *sizep"
  50 .Sh DESCRIPTION
  51 The
  52 .Fn sysctl
  53 function retrieves system information and allows processes with
  54 appropriate privileges to set system information.
  55 The information available from
  56 .Fn sysctl
  57 consists of integers, strings, and tables.
  58 Information may be retrieved and set from the command interface
  59 using the
  60 .Xr sysctl 8
  61 utility.
  62 .Pp
  63 Unless explicitly noted below,
  64 .Fn sysctl
  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.
  68 Calls to
  69 .Fn sysctl
  70 are serialized to avoid deadlock.
  71 .Pp
  72 The state is described using a ``Management Information Base'' (MIB)
  73 style name, listed in
  74 .Fa name ,
  75 which is a
  76 .Fa namelen
  77 length array of integers.
  78 .Pp
  79 The
  80 .Fn sysctlbyname
  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
  84 as the standard
  85 .Fn sysctl
  86 function.
  87 .Pp
  88 The information is copied into the buffer specified by
  89 .Fa oldp .
  90 The size of the buffer is given by the location specified by
  91 .Fa oldlenp
  92 before the call,
  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
  95 .Er ENOMEM .
  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
 100 .Er ENOMEM .
 101 If the old value is not desired,
 102 .Fa oldp
 103 and
 104 .Fa oldlenp
 105 should be set to NULL.
 106 .Pp
 107 The size of the available data can be determined by calling
 108 .Fn sysctl
 109 with the
 110 .Dv NULL
 111 argument for
 112 .Fa oldp .
 113 The size of the available data will be returned in the location pointed to by
 114 .Fa oldlenp .
 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.
 119 .Pp
 120 To set a new value,
 121 .Fa newp
 122 is set to point to a buffer of length
 123 .Fa newlen
 124 from which the requested value is to be taken.
 125 If a new value is not to be set,
 126 .Fa newp
 127 should be set to NULL and
 128 .Fa newlen
 129 set to 0.
 130 .Pp
 131 The
 132 .Fn sysctlnametomib
 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
 136 .Fa mibp .
 137 The number of elements in the mib array is given by the location specified by
 138 .Fa sizep
 139 before the call,
 140 and that location gives the number of entries copied after a successful call.
 141 The resulting
 142 .Fa mib
 143 and
 144 .Fa size
 145 may be used in subsequent
 146 .Fn sysctl
 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
 150 .Fn sysctl
 151 function runs in about a third the time as the same request made via the
 152 .Fn sysctlbyname
 153 function).
 154 .Pp
 155 The top level names are defined with a CTL_ prefix in
 156 .In sys/sysctl.h ,
 157 and are as follows.
 158 The next and subsequent levels down are found in the include files
 159 listed here, and described in separate sections below.
 160 .Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent
 161 .It Sy "Name    Next level names        Description"
 162 .It "CTL_DEBUG  sys/sysctl.h    Debugging"
 163 .It "CTL_VFS    sys/mount.h     File system"
 164 .It "CTL_HW     sys/sysctl.h    Generic CPU, I/O"
 165 .It "CTL_KERN   sys/sysctl.h    High kernel limits"
 166 .It "CTL_MACHDEP        sys/sysctl.h    Machine dependent"
 167 .It "CTL_NET    sys/socket.h    Networking"
 168 .It "CTL_USER   sys/sysctl.h    User-level"
 169 .It "CTL_VM     sys/resources.h Virtual memory (struct loadavg)"
 170 .El
 171 .Pp
 172 For example, the following retrieves the maximum number of processes allowed
 173 in the system:
 174 .Pp
 175 .Bd -literal -offset indent -compact
 176 int maxproc;
 177 size_t len = sizeof(maxproc);
 178 sysctlbyname("kern.maxproc", &maxproc, &len, NULL, 0);
 179 .Ed
 180 .Pp
 181 To retrieve the standard search path for the system utilities:
 182 .Pp
 183 .Bd -literal -offset indent -compact
 184 char *p;
 185 size_t len;
 186 sysctlbyname("user.cs_path", NULL, &len, NULL, 0);
 187 p = malloc(len);
 188 sysctlbyname("user.cs_path", p, &len, NULL, 0);
 189 .Ed
 190 .Ss CTL_VFS
 191 A distinguished second level name, VFS_GENERIC,
 192 is used to get general information about all file systems.
 193 One of its third level identifiers is VFS_MAXTYPENUM
 194 that gives the highest valid file system type number.
 195 Its other third level identifier is VFS_CONF that
 196 returns configuration information about the file system
 197 type given as a fourth level identifier (see
 198 .Xr getvfsbyname 3
 199 as an example of its use).
 200 The remaining second level identifiers are the
 201 file system type number returned by a
 202 .Xr statfs 2
 203 call or from VFS_CONF.
 204 The third level identifiers available for each file system
 205 are given in the header file that defines the mount
 206 argument structure for that file system.
 207 .Ss CTL_HW
 208 The string and integer information available for the CTL_HW level
 209 is detailed below.
 210 The changeable column shows whether a process with appropriate
 211 privilege may change the value.
 212 .Bl -column "xxxxxxxxxxxxxxxxxxxxxxxxx" "xxxxxxxxxx" -offset indent
 213 .It Sy "Name    Type    Changeable"
 214 .It "hw.activecpu       int32_t no"
 215 .It "hw.byteorder       int32_t no"
 216 .It "hw.cacheconfig     uint64_t[]      no"
 217 .It "hw.cachelinesize   int64_t no"
 218 .It "hw.cachesize       uint64_t[]      no"
 219 .It "hw.cpu64bit_capable        int32_t no"
 220 .It "hw.cpufamily       int32_t no"
 221 .It "hw.cpufrequency    int64_t no"
 222 .It "hw.cpufrequency_max        int64_t no"
 223 .It "hw.cpufrequency_min        int64_t no"
 224 .It "hw.cpusubtype      int32_t no"
 225 .It "hw.cputhreadtype   int32_t no"
 226 .It "hw.cputype int32_t no"
 227 .It "hw.l1dcachesize    int64_t no"
 228 .It "hw.l1icachesize    int64_t no"
 229 .It "hw.l2cachesize     int64_t no"
 230 .It "hw.l3cachesize     int64_t no"
 231 .It "hw.logicalcpu      int32_t no"
 232 .It "hw.logicalcpu_max  int32_t no"
 233 .It "hw.machine char[]  no"
 234 .It "hw.memsize int64_t no"
 235 .It "hw.model   char[]  no"
 236 .It "hw.ncpu    int32_t no"
 237 .It "hw.packages        int32_t no"
 238 .It "hw.pagesize        int64_t no"
 239 .It "hw.physicalcpu     int32_t no"
 240 .It "hw.physicalcpu_max int32_t no"
 241 .It "hw.tbfrequency     int64_t no"
 242 .El
 243 .Bl -tag -width 6n
 244 .It Li "hw.byteorder"
 245 The byte order (4321 or 1234).
 246 .It Li "hw.model"
 247 The machine model.
 248 .It Li "hw.ncpu"
 249 The number of cpus. This attribute is deprecated and it is recommended that
 250 .Va "hw.logicalcpu" ,
 251 .Va "hw.logicalcpu_max" ,
 252 .Va "hw.physicalcpu" ,
 253 or
 254 .Va "hw.physicalcpu_max"
 255 be used instead.
 256 .It Li "hw.logicalcpu"
 257 The number of logical processors available in the current power management mode.
 258 .It Li "hw.logicalcpu_max"
 259 The maximum number of logical processors that could be available this boot.
 260 .It Li "hw.physicalcpu"
 261 The number of physical processors available in the current power management mode.
 262 .It Li "hw.physicalcpu_max"
 263 The maximum number of physical processors that could be available this boot.
 264 .It Li "hw.pagesize"
 265 The software page size in bytes.
 266 .El
 267 .Ss CTL_KERN
 268 The string and integer information available for the CTL_KERN level
 269 is detailed below.
 270 The changeable column shows whether a process with appropriate
 271 privilege may change the value.
 272 The types of data currently available are process information,
 273 system vnodes, the open file entries, routing table entries,
 274 virtual memory statistics, load average history, and clock rate
 275 information.
 276 .Bl -column "xxxxxxxxxxxxxxxxxxxxxxxxx" "xxxxxxxxxxxxxxxxxxxx" -offset indent
 277 .It Sy "Name    Type    Changeable"
 278 .It "kern.argmax        int32_t no"
 279 .It "kern.bootargs      char[]  no"
 280 .It "kern.boottime      struct timeval  no"
 281 .It "kern.check_openevt int32_t yes"
 282 .It "kern.clockrate     struct clockinfo        no"
 283 .It "kern.coredump      int32_t yes"
 284 .It "kern.corefile      char[]  yes"
 285 .It "kern.flush_cache_on_write  int32_t yes"
 286 .It "kern.hostid        int32_t yes"
 287 .It "kern.hostname      char[]  yes"
 288 .It "kern.job_control   int32_t no"
 289 .It "kern.maxfiles      int32_t yes"
 290 .It "kern.maxfilesperproc       int32_t yes"
 291 .It "kern.maxnbuf       int32_t yes"
 292 .It "kern.maxproc       int32_t yes"
 293 .It "kern.maxprocperuid int32_t yes"
 294 .It "kern.maxvnodes     int32_t yes"
 295 .It "kern.msgbuf        int32_t yes"
 296 .It "kern.nbuf  int32_t no"
 297 .It "kern.netboot       int32_t no"
 298 .It "kern.ngroups       int32_t no"
 299 .It "kern.nisdomainname char[]  yes"
 300 .It "kern.num_files     int32_t no"
 301 .It "kern.num_tasks     int32_t no"
 302 .It "kern.num_taskthreads       int32_t no"
 303 .It "kern.num_threads   int32_t no"
 304 .It "kern.num_vnodes    int32_t no"
 305 .It "kern.nx    int32_t yes"
 306 .It "kern.osrelease     char[]  no"
 307 .It "kern.osrevision    int32_t no"
 308 .It "kern.ostype        char[]  no"
 309 .It "kern.osversion     char[]  yes"
 310 .It "kern.posix1version int32_t no"
 311 .It "kern.procname      char[]  yes"
 312 .It "kern.safeboot      int32_t no"
 313 .It "kern.saved_ids     int32_t no"
 314 .It "kern.secure_kernel int32_t no"
 315 .It "kern.securelevel   int32_t yes"
 316 .It "kern.singleuser    int32_t no"
 317 .It "kern.sleeptime     struct timeval  no"
 318 .It "kern.slide int32_t no"
 319 .It "kern.stack_depth_max       int32_t no"
 320 .It "kern.stack_size    int32_t no"
 321 .It "kern.sugid_coredump        int32_t yes"
 322 .It "kern.sugid_scripts int32_t yes"
 323 .It "kern.symfile       char[]  no"
 324 .It "kern.usrstack      int32_t no"
 325 .It "kern.usrstack64    int64_t no"
 326 .It "kern.uuid  char[]  no"
 327 .It "kern.version       char[]  no"
 328 .It "kern.waketime      struct timeval  no"
 329 .El
 330 .Bl -tag -width 6n
 331 .It Li "kern.argmax"
 332 The maximum bytes of argument to
 333 .Xr execve 2 .
 334 .It Li "kern.boottime"
 335 A
 336 .Va struct timeval
 337 structure is returned.
 338 This structure contains the time that the system was booted.
 339 .It Li "kern.clockrate"
 340 A
 341 .Va struct clockinfo
 342 structure is returned.
 343 This structure contains the clock, statistics clock and profiling clock
 344 frequencies, the number of micro-seconds per hz tick and the skew rate.
 345 .It Li "kern.hostid"
 346 Get or set the host id.
 347 .It Li "kern.hostname"
 348 Get or set the hostname.
 349 .It Li "kern.job_control"
 350 Return 1 if job control is available on this system, otherwise 0.
 351 .It Li "kern.maxfiles"
 352 The maximum number of files that may be open in the system.
 353 .It Li "kern.maxfilesperproc"
 354 The maximum number of files that may be open for a single process.
 355 This limit only applies to processes with an effective uid of nonzero
 356 at the time of the open request.
 357 Files that have already been opened are not affected if the limit
 358 or the effective uid is changed.
 359 .It Li "kern.maxproc"
 360 The maximum number of concurrent processes the system will allow.
 361 .It Li "kern.maxprocperuid"
 362 The maximum number of concurrent processes the system will allow
 363 for a single effective uid.
 364 This limit only applies to processes with an effective uid of nonzero
 365 at the time of a fork request.
 366 Processes that have already been started are not affected if the limit
 367 is changed.
 368 .It Li "kern.maxvnodes"
 369 The maximum number of vnodes available on the system.
 370 .It Li "kern.ngroups"
 371 The maximum number of supplemental groups.
 372 .It Li "kern.nisdomainname"
 373 The name of the current YP/NIS domain.
 374 .It Li "kern.osrelease"
 375 The system release string.
 376 .It Li "kern.osrevision"
 377 The system revision number.
 378 .It Li "kern.ostype"
 379 The system type string.
 380 .It Li "kern.posix1version"
 381 The version of
 382 .St -p1003.1
 383 with which the system
 384 attempts to comply.
 385 .It Li "kern.saved_ids"
 386 Returns 1 if saved set-group and saved set-user ID is available.
 387 .It Li "kern.securelevel"
 388 The system security level.
 389 This level may be raised by processes with appropriate privilege.
 390 It may not be lowered.
 391 .It Li "kern.version"
 392 The system version string.
 393 .El
 394 .Ss CTL_MACHDEP
 395 The set of variables defined is architecture dependent.
 396 The following variables are defined for the i386 architecture.
 397 .Bl -column "xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx" "xxxxxxxxxx" -offset indent
 398 .It Sy "Name    Type    Changeable"
 399 .It "machdep.cpu.address_bits.physical  int32_t no"
 400 .It "machdep.cpu.address_bits.virtual   int32_t no"
 401 .It "machdep.cpu.brand  int32_t no"
 402 .It "machdep.cpu.brand_string   char[]  no"
 403 .It "machdep.cpu.cache.L2_associativity int32_t no"
 404 .It "machdep.cpu.cache.linesize int32_t no"
 405 .It "machdep.cpu.cache.size     int32_t no"
 406 .It "machdep.cpu.core_count     int32_t no"
 407 .It "machdep.cpu.cores_per_package      int32_t no"
 408 .It "machdep.cpu.extfamily      int32_t no"
 409 .It "machdep.cpu.extfeature_bits        int64_t no"
 410 .It "machdep.cpu.extfeatures    char[]  no"
 411 .It "machdep.cpu.extmodel       int32_t no"
 412 .It "machdep.cpu.family int32_t no"
 413 .It "machdep.cpu.feature_bits   int64_t no"
 414 .It "machdep.cpu.features       char[]  no"
 415 .It "machdep.cpu.leaf7_feature_bits     uint32_t        no"
 416 .It "machdep.cpu.leaf7_features char[]  no"
 417 .It "machdep.cpu.logical_per_package    int32_t no"
 418 .It "machdep.cpu.max_basic      uint32_t        no"
 419 .It "machdep.cpu.max_ext        uint32_t        no"
 420 .It "machdep.cpu.microcode_version      int32_t no"
 421 .It "machdep.cpu.model  int32_t no"
 422 .It "machdep.cpu.processor_flag int32_t no"
 423 .It "machdep.cpu.signature      int32_t no"
 424 .It "machdep.cpu.stepping       int32_t no"
 425 .It "machdep.cpu.thread_count   int32_t no"
 426 .It "machdep.cpu.tlb.data.large int32_t no"
 427 .It "machdep.cpu.tlb.data.large_level1  int32_t no"
 428 .It "machdep.cpu.tlb.data.small int32_t no"
 429 .It "machdep.cpu.tlb.data.small_level1  int32_t no"
 430 .It "machdep.cpu.tlb.inst.large int32_t no"
 431 .It "machdep.cpu.tlb.inst.small int32_t no"
 432 .It "machdep.cpu.tlb.shared     int32_t no"
 433 .It "machdep.cpu.ucupdate       int32_t yes"
 434 .It "machdep.cpu.vendor char[]  no"
 435 .It "machdep.cpu.xsave.extended_state   uint32_t        no"
 436 .It "machdep.tsc.deep_idle_rebase       uint32_t        yes"
 437 .It "machdep.tsc.frequency      int64_t no"
 438 .It "machdep.tsc.nanotime.generation    uint32_t        no"
 439 .It "machdep.tsc.nanotime.shift uint32_t        no"
 440 .El
 441 .Ss CTL_NET
 442 The string and integer information available for the CTL_NET level
 443 is detailed below.
 444 The changeable column shows whether a process with appropriate
 445 privilege may change the value.
 446 .Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent
 447 .It Sy "Second level name       Type    Changeable"
 448 .It "PF_ROUTE   routing messages        no"
 449 .It "PF_INET    IPv4 values     yes"
 450 .It "PF_INET6   IPv6 values     yes"
 451 .El
 452 .Bl -tag -width 6n
 453 .It Li PF_ROUTE
 454 Return the entire routing table or a subset of it.
 455 The data is returned as a sequence of routing messages (see
 456 .Xr route 4
 457 for the header file, format and meaning).
 458 The length of each message is contained in the message header.
 459 .Pp
 460 The third level name is a protocol number, which is currently always 0.
 461 The fourth level name is an address family, which may be set to 0 to
 462 select all address families.
 463 The fifth, sixth, and seventh level names are as follows:
 464 .Bl -column -offset indent "Fifth level      Sixth level" "Seventh level"
 465 .It Sy "Fifth level      Sixth level" Ta Sy "Seventh level"
 466 .It "NET_RT_FLAGS     rtflags" Ta "None"
 467 .It "NET_RT_DUMP      None" Ta "None or fib number"
 468 .It "NET_RT_IFLIST    0 or if_index" Ta None
 469 .It "NET_RT_IFMALIST  0 or if_index" Ta None
 470 .It "NET_RT_IFLISTL   0 or if_index" Ta None
 471 .El
 472 .Pp
 473 The
 474 .Dv NET_RT_IFMALIST
 475 name returns information about multicast group memberships on all interfaces
 476 if 0 is specified, or for the interface specified by
 477 .Va if_index .
 478 .It Li PF_INET
 479 Get or set various global information about the IPv4
 480 (Internet Protocol version 4).
 481 The third level name is the protocol.
 482 The fourth level name is the variable name.
 483 The currently defined protocols and names are:
 484 .Bl -column ProtocolXX VariableXX TypeXX ChangeableXX
 485 .It Sy "Protocol        Variable        Type    Changeable"
 486 .It "icmp       bmcastecho      integer yes"
 487 .It "icmp       maskrepl        integer yes"
 488 .It "ip forwarding      integer yes"
 489 .It "ip redirect        integer yes"
 490 .It "ip ttl     integer yes"
 491 .It "udp        checksum        integer yes"
 492 .El
 493 .Pp
 494 The variables are as follows:
 495 .Bl -tag -width 6n
 496 .It Li icmp.bmcastecho
 497 Returns 1 if an ICMP echo request to a broadcast or multicast address is
 498 to be answered.
 499 .It Li icmp.maskrepl
 500 Returns 1 if ICMP network mask requests are to be answered.
 501 .It Li ip.forwarding
 502 Returns 1 when IP forwarding is enabled for the host,
 503 meaning that the host is acting as a router.
 504 .It Li ip.redirect
 505 Returns 1 when ICMP redirects may be sent by the host.
 506 This option is ignored unless the host is routing IP packets,
 507 and should normally be enabled on all systems.
 508 .It Li ip.ttl
 509 The maximum time-to-live (hop count) value for an IP packet sourced by
 510 the system.
 511 This value applies to normal transport protocols, not to ICMP.
 512 .It Li udp.checksum
 513 Returns 1 when UDP checksums are being computed and checked.
 514 Disabling UDP checksums is strongly discouraged.
 515 .Pp
 516 For variables net.inet.*.ipsec, please refer to
 517 .Xr ipsec 4 .
 518 .El
 519 .It Li PF_INET6
 520 Get or set various global information about the IPv6
 521 (Internet Protocol version 6).
 522 The third level name is the protocol.
 523 The fourth level name is the variable name.
 524 .Pp
 525 For variables net.inet6.* please refer to
 526 .Xr inet6 4 .
 527 For variables net.inet6.*.ipsec6, please refer to
 528 .Xr ipsec 4 .
 529 .El
 530 .Ss CTL_USER
 531 The string and integer information available for the CTL_USER level
 532 is detailed below.
 533 The changeable column shows whether a process with appropriate
 534 privilege may change the value.
 535 .Bl -column "xxxxxxxxxxxxxxxxxxxxxxxxx" "xxxxxxxxxx" -offset indent
 536 .It Sy "Name    Type    Changeable"
 537 .It "user.bc_base_max   int32_t no"
 538 .It "user.bc_dim_max    int32_t no"
 539 .It "user.bc_scale_max  int32_t no"
 540 .It "user.bc_string_max int32_t no"
 541 .It "user.coll_weights_max      int32_t no"
 542 .It "user.cs_path       char[]  no"
 543 .It "user.expr_nest_max int32_t no"
 544 .It "user.line_max      int32_t no"
 545 .It "user.posix2_c_bind int32_t no"
 546 .It "user.posix2_c_dev  int32_t no"
 547 .It "user.posix2_char_term      int32_t no"
 548 .It "user.posix2_fort_dev       int32_t no"
 549 .It "user.posix2_fort_run       int32_t no"
 550 .It "user.posix2_localedef      int32_t no"
 551 .It "user.posix2_sw_dev int32_t no"
 552 .It "user.posix2_upe    int32_t no"
 553 .It "user.posix2_version        int32_t no"
 554 .It "user.re_dup_max    int32_t no"
 555 .It "user.stream_max    int32_t no"
 556 .It "user.tzname_max    int32_t no"
 557 .El
 558 .Bl -tag -width 6n
 559 .Pp
 560 .It Li "user.bc_base_max"
 561 The maximum ibase/obase values in the
 562 .Xr bc 1
 563 utility.
 564 .It Li "user.bc_dim_max"
 565 The maximum array size in the
 566 .Xr bc 1
 567 utility.
 568 .It Li "user.bc_scale_max"
 569 The maximum scale value in the
 570 .Xr bc 1
 571 utility.
 572 .It Li "user.bc_string_max"
 573 The maximum string length in the
 574 .Xr bc 1
 575 utility.
 576 .It Li "user.coll_weights_max"
 577 The maximum number of weights that can be assigned to any entry of
 578 the LC_COLLATE order keyword in the locale definition file.
 579 .It Li "user.cs_path"
 580 Return a value for the
 581 .Ev PATH
 582 environment variable that finds all the standard utilities.
 583 .It Li "user.expr_nest_max"
 584 The maximum number of expressions that can be nested within
 585 parenthesis by the
 586 .Xr expr 1
 587 utility.
 588 .It Li "user.line_max"
 589 The maximum length in bytes of a text-processing utility's input
 590 line.
 591 .It Li "user.posix2_c_bind"
 592 Return 1 if the system's C-language development facilities support the
 593 C-Language Bindings Option, otherwise 0.
 594 .It Li "user.posix2_c_dev"
 595 Return 1 if the system supports the C-Language Development Utilities Option,
 596 otherwise 0.
 597 .It Li "user.posix2_char_term"
 598 Return 1 if the system supports at least one terminal type capable of
 599 all operations described in
 600 .St -p1003.2 ,
 601 otherwise 0.
 602 .It Li "user.posix2_fort_dev"
 603 Return 1 if the system supports the FORTRAN Development Utilities Option,
 604 otherwise 0.
 605 .It Li "user.posix2_fort_run"
 606 Return 1 if the system supports the FORTRAN Runtime Utilities Option,
 607 otherwise 0.
 608 .It Li "user.posix2_localedef"
 609 Return 1 if the system supports the creation of locales, otherwise 0.
 610 .It Li "user.posix2_sw_dev"
 611 Return 1 if the system supports the Software Development Utilities Option,
 612 otherwise 0.
 613 .It Li "user.posix2_upe"
 614 Return 1 if the system supports the User Portability Utilities Option,
 615 otherwise 0.
 616 .It Li "user.posix2_version"
 617 The version of
 618 .St -p1003.2
 619 with which the system attempts to comply.
 620 .It Li "user.re_dup_max"
 621 The maximum number of repeated occurrences of a regular expression
 622 permitted when using interval notation.
 623 .It Li "user.stream_max"
 624 The minimum maximum number of streams that a process may have open
 625 at any one time.
 626 .It Li "user.tzname_max"
 627 The minimum maximum number of types supported for the name of a
 628 timezone.
 629 .El
 630 .Ss CTL_VM
 631 The string and integer information available for the CTL_VM level
 632 is detailed below.
 633 The changeable column shows whether a process with appropriate
 634 privilege may change the value.
 635 .Bl -column "xxxxxxxxxxxxxxxxxxxxxxxxx" "xxxxxxxxxx" -offset indent
 636 .It Sy "Name    Type    Changeable"
 637 .It "vm.loadavg struct loadavg  no"
 638 .It "vm.swapusage       struct xsw_usage        no"
 639 .El
 640 .Pp
 641 .Bl -tag -width 6n
 642 .It Li "vm.loadavg"
 643 Return the load average history.
 644 The returned data consists of a
 645 .Va struct loadavg .
 646 .El
 647 .Sh RETURN VALUES
 648 .Rv -std
 649 .Sh FILES
 650 .Bl -tag -width <netinet/icmpXvar.h> -compact
 651 .It In sys/sysctl.h
 652 definitions for top level identifiers, second level kernel and hardware
 653 identifiers, and user level identifiers
 654 .It In sys/socket.h
 655 definitions for second level network identifiers
 656 .It In netinet/in.h
 657 definitions for third level IPv4/IPv6 identifiers and
 658 fourth level IPv4/v6 identifiers
 659 .It In netinet/icmp_var.h
 660 definitions for fourth level ICMP identifiers
 661 .It In netinet/icmp6.h
 662 definitions for fourth level ICMPv6 identifiers
 663 .It In netinet/udp_var.h
 664 definitions for fourth level UDP identifiers
 665 .El
 666 .Sh ERRORS
 667 The following errors may be reported:
 668 .Bl -tag -width Er
 669 .It Bq Er EFAULT
 670 The buffer
 671 .Fa name ,
 672 .Fa oldp ,
 673 .Fa newp ,
 674 or length pointer
 675 .Fa oldlenp
 676 contains an invalid address.
 677 .It Bq Er EINVAL
 678 The
 679 .Fa name
 680 array is less than two or greater than CTL_MAXNAME.
 681 .It Bq Er EINVAL
 682 A non-null
 683 .Fa newp
 684 is given and its specified length in
 685 .Fa newlen
 686 is too large or too small.
 687 .It Bq Er ENOMEM
 688 The length pointed to by
 689 .Fa oldlenp
 690 is too short to hold the requested value.
 691 .It Bq Er ENOMEM
 692 The smaller of either the length pointed to by
 693 .Fa oldlenp
 694 or the estimated size of the returned data exceeds the
 695 system limit on locked memory.
 696 .It Bq Er ENOMEM
 697 Locking the buffer
 698 .Fa oldp ,
 699 or a portion of the buffer if the estimated size of the data
 700 to be returned is smaller,
 701 would cause the process to exceed its per-process locked memory limit.
 702 .It Bq Er ENOTDIR
 703 The
 704 .Fa name
 705 array specifies an intermediate rather than terminal name.
 706 .It Bq Er EISDIR
 707 The
 708 .Fa name
 709 array specifies a terminal name, but the actual name is not terminal.
 710 .It Bq Er ENOENT
 711 The
 712 .Fa name
 713 array specifies a value that is unknown.
 714 .It Bq Er EPERM
 715 An attempt is made to set a read-only value.
 716 .It Bq Er EPERM
 717 A process without appropriate privilege attempts to set a value.
 718 .El
 719 .Sh SEE ALSO
 720 .Xr confstr 3 ,
 721 .Xr sysconf 3 ,
 722 .Xr sysctl 8
 723 .Sh HISTORY
 724 The
 725 .Fn sysctl
 726 function first appeared in
 727 .Bx 4.4 .