1.\" $NetBSD: sysctl.3,v 1.52 2000/02/27 06:13:35 itojun Exp $ 2.\" 3.\" Copyright (c) 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 3. All advertising materials mentioning features or use of this software 15.\" must display the following acknowledgement: 16.\" This product includes software developed by the University of 17.\" California, Berkeley and its contributors. 18.\" 4. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" @(#)sysctl.3 8.4 (Berkeley) 5/9/95 35.\" 36.Dd June 24, 1999 37.Dt SYSCTL 3 38.Os 39.Sh NAME 40.Nm sysctl 41.Nd get or set system information 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.Fd #include <sys/param.h> 46.Fd #include <sys/sysctl.h> 47.Ft int 48.Fn sysctl "int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" 49.Sh DESCRIPTION 50The 51.Nm 52function retrieves system information and allows processes with 53appropriate privileges to set system information. 54The information available from 55.Nm 56consists of integers, strings, and tables. 57Information may be retrieved and set from the command interface 58using the 59.Xr sysctl 8 60utility. 61.Pp 62Unless explicitly noted below, 63.Nm 64returns a consistent snapshot of the data requested. 65Consistency is obtained by locking the destination 66buffer into memory so that the data may be copied out without blocking. 67Calls to 68.Nm 69are serialized to avoid deadlock. 70.Pp 71The state is described using a ``Management Information Base'' (MIB) 72style name, listed in 73.Fa name , 74which is a 75.Fa namelen 76length array of integers. 77.Pp 78The information is copied into the buffer specified by 79.Fa oldp . 80The size of the buffer is given by the location specified by 81.Fa oldlenp 82before the call, 83and that location gives the amount of data copied after a successful call. 84If the amount of data available is greater 85than the size of the buffer supplied, 86the call supplies as much data as fits in the buffer provided 87and returns with the error code ENOMEM. 88If the old value is not desired, 89.Fa oldp 90and 91.Fa oldlenp 92should be set to NULL. 93.Pp 94The size of the available data can be determined by calling 95.Nm 96with a NULL parameter for 97.Fa oldp . 98The size of the available data will be returned in the location pointed to by 99.Fa oldlenp . 100For some operations, the amount of space may change often. 101For these operations, 102the system attempts to round up so that the returned size is 103large enough for a call to return the data shortly thereafter. 104.Pp 105To set a new value, 106.Fa newp 107is set to point to a buffer of length 108.Fa newlen 109from which the requested value is to be taken. 110If a new value is not to be set, 111.Fa newp 112should be set to NULL and 113.Fa newlen 114set to 0. 115.Pp 116The top level names are defined with a CTL_ prefix in 117.Pa <sys/sysctl.h> , 118and are as follows. 119The next and subsequent levels down are found in the include files 120listed here, and described in separate sections below. 121.Pp 122.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent 123.It Sy Pa Name Next level names Description 124.It CTL\_DEBUG sys/sysctl.h Debugging 125.It CTL\_VFS sys/mount.h Filesystem 126.It CTL\_HW sys/sysctl.h Generic CPU, I/O 127.It CTL\_KERN sys/sysctl.h High kernel limits 128.It CTL\_MACHDEP sys/sysctl.h Machine dependent 129.It CTL\_NET sys/socket.h Networking 130.It CTL\_PROC sys/sysctl.h Per-process 131.It CTL\_USER sys/sysctl.h User-level 132.It CTL\_VM vm/vm_param.h Virtual memory 133.El 134.Pp 135For example, the following retrieves the maximum number of processes allowed 136in the system: 137.Bd -literal -offset indent -compact 138int mib[2], maxproc; 139size_t len; 140.sp 141mib[0] = CTL_KERN; 142mib[1] = KERN_MAXPROC; 143len = sizeof(maxproc); 144sysctl(mib, 2, &maxproc, &len, NULL, 0); 145.Ed 146.sp 147To retrieve the standard search path for the system utilities: 148.Bd -literal -offset indent -compact 149int mib[2]; 150size_t len; 151char *p; 152.sp 153mib[0] = CTL_USER; 154mib[1] = USER_CS_PATH; 155sysctl(mib, 2, NULL, &len, NULL, 0); 156p = malloc(len); 157sysctl(mib, 2, p, &len, NULL, 0); 158.Ed 159.Sh CTL_DEBUG 160The debugging variables vary from system to system. 161A debugging variable may be added or deleted without need to recompile 162.Nm 163to know about it. 164Each time it runs, 165.Nm 166gets the list of debugging variables from the kernel and 167displays their current values. 168The system defines twenty 169.Ns ( Va struct ctldebug ) 170variables named 171.Dv debug0 172through 173.Dv debug19 . 174They are declared as separate variables so that they can be 175individually initialized at the location of their associated variable. 176The loader prevents multiple use of the same variable by issuing errors 177if a variable is initialized in more than one place. 178For example, to export the variable 179.Dv dospecialcheck 180as a debugging variable, the following declaration would be used: 181.Bd -literal -offset indent -compact 182int dospecialcheck = 1; 183struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck }; 184.Ed 185.Sh CTL_VFS 186A distinguished second level name, VFS_GENERIC, 187is used to get general information about all filesystems. 188One of its third level identifiers is VFS_MAXTYPENUM 189that gives the highest valid filesystem type number. 190Its other third level identifier is VFS_CONF that 191returns configuration information about the filesystem 192type given as a fourth level identifier (see 193.Xr getvfsbyname 3 194as an example of its use). 195The remaining second level identifiers are the 196filesystem type number returned by a 197.Xr statfs 2 198call or from VFS_CONF. 199The third level identifiers available for each filesystem 200are given in the header file that defines the mount 201argument structure for that filesystem. 202.Sh CTL_HW 203The string and integer information available for the CTL_HW level 204is detailed below. 205The changeable column shows whether a process with appropriate 206privilege may change the value. 207.Bl -column "Second level nameXXXXXX" integerXXX -offset indent 208.It Sy Pa Second level name Type Changeable 209.It HW\_MACHINE string no 210.It HW\_MODEL string no 211.It HW\_NCPU integer no 212.It HW\_BYTEORDER integer no 213.It HW\_PHYSMEM integer no 214.It HW\_USERMEM integer no 215.It HW\_PAGESIZE integer no 216.\".It HW\_DISKNAMES struct no 217.\".It HW\_DISKSTATS struct no 218.It HW\_MACHINE\_ARCH string no 219.It HW\_ALIGNBYTES integer no 220.El 221.Pp 222.Bl -tag -width "123456" 223.It Li HW_MACHINE 224The machine class. 225.It Li HW_MODEL 226The machine model 227.It Li HW_NCPU 228The number of cpus. 229.ne 1i 230.It Li HW_BYTEORDER 231The byteorder (4,321, or 1,234). 232.It Li HW_PHYSMEM 233The bytes of physical memory. 234.It Li HW_USERMEM 235The bytes of non-kernel memory. 236.It Li HW_PAGESIZE 237The software page size. 238.\".It Fa HW_DISKNAMES 239.\".It Fa HW_DISKSTATS 240.It Li HW_MACHINE_ARCH 241The machine cpu class. 242.It Li HW_ALIGNBYTES 243Alignment constraint for all possible data types. 244This shows the value 245.Dv ALIGNBYTES 246in 247.Pa /usr/include/machine/param.h , 248at the kernel compilation time. 249.El 250.Sh CTL_KERN 251The string and integer information available for the CTL_KERN level 252is detailed below. 253The changeable column shows whether a process with appropriate 254privilege may change the value. 255The types of data currently available are process information, 256system vnodes, the open file entries, routing table entries, 257virtual memory statistics, load average history, and clock rate 258information. 259.Bl -column "KERNXCHOWNXRESTRICTEDXXX" "struct clockrateXXX" -offset indent 260.It Sy Pa Second level name Type Changeable 261.It KERN\_ARGMAX integer no 262.It KERN\_AUTONICETIME integer yes 263.It KERN\_AUTONICEVAL integer yes 264.It KERN\_BOOTTIME struct timeval no 265.It KERN\_CHOWN\_RESTRICTED integer no 266.It KERN\_CLOCKRATE struct clockinfo no 267.It KERN\_DEFCORENAME string yes 268.It KERN\_DOMAINNAME string yes 269.It KERN\_FILE struct file no 270.It KERN\_FSYNC integer no 271.It KERN\_HOSTID integer yes 272.It KERN\_HOSTNAME string yes 273.It KERN\_IOV\_MAX integer no 274.It KERN\_JOB\_CONTROL integer no 275.It KERN\_LINK\_MAX integer no 276.It KERN\_LOGIN\_NAME\_MAX integer no 277.It KERN\_LOGSIGEXIT integer yes 278.It KERN\_MAPPED\_FILES integer no 279.It KERN\_MAXFILES integer yes 280.It KERN\_MAXPARTITIONS integer no 281.It KERN\_MAXPROC integer yes 282.It KERN\_MAXVNODES integer yes 283.It KERN\_MAX\_CANON integer no 284.It KERN\_MAX\_INPUT integer no 285.It KERN\_MEMLOCK integer no 286.It KERN\_MEMLOCK\_RANGE integer no 287.It KERN\_MEMORY\_PROTECTION integer no 288.It KERN\_MSGBUFSIZE integer no 289.It KERN\_NAME\_MAX integer no 290.It KERN\_NGROUPS integer no 291.It KERN\_NO\_TRUNC integer no 292.It KERN\_OSRELEASE string no 293.It KERN\_OSREV integer no 294.It KERN\_OSTYPE string no 295.It KERN\_PATH\_MAX integer no 296.It KERN\_PIPE\_BUF integer no 297.It KERN\_POSIX1 integer no 298.It KERN\_PROC struct proc no 299.It KERN\_PROF node not applicable 300.It KERN\_RAWPARTITION integer no 301.It KERN\_SAVED\_IDS integer no 302.It KERN\_SECURELVL integer raise only 303.It KERN\_SYNCHRONIZED\_IO integer no 304.It KERN\_SYSVMSG integer no 305.It KERN\_SYSVSEM integer no 306.It KERN\_SYSVSHM integer no 307.It KERN\_VDISABLE integer no 308.It KERN\_VERSION string no 309.It KERN\_VNODE struct vnode no 310.El 311.ne 1i 312.Pp 313.Bl -tag -width "123456" 314.It Li KERN_ARGMAX 315The maximum bytes of argument to 316.Xr execve 2 . 317.It Li KERN_AUTONICETIME 318The number of seconds of cpu-time a non-root process may accumulate before 319having its priority lowered from the default to the value of KERN_AUTONICEVAL. 320If set to 0, automatic lowering of priority is not performed, and if set to -1 321all non-root processes are immediately lowered. 322.It Li KERN_AUTONICEVAL 323The priority assigned for automatically niced processes. 324.It Li KERN_BOOTTIME 325A 326.Va struct timeval 327structure is returned. 328This structure contains the time that the system was booted. 329.It Li KERN_CHOWN_RESTRICTED 330Return 1 if appropriate privileges are required for the 331.Xr chown 2 332system call, otherwise 0. 333.It Li KERN_CLOCKRATE 334A 335.Va struct clockinfo 336structure is returned. 337This structure contains the clock, statistics clock and profiling clock 338frequencies, the number of micro-seconds per hz tick, and the clock 339skew rate. 340.It Li KERN_DEFCORENAME 341Default template for the name of core dump files (see also PROC_PID_CORENAME 342in the per-process variables CTL_PROC, and 343.Xr core 5 344for format of this template). The default value is 345.Nm %n.core 346and can be changed with the kernel configuration option 347.Cd options DEFCORENAME 348(see 349.Xr options 4 350). 351.It Li KERN_DOMAINNAME 352Get or set the YP domain name. 353.It Li KERN_FILE 354Return the entire file table. 355The returned data consists of a single 356.Va struct filehead 357followed by an array of 358.Va struct file , 359whose size depends on the current number of such objects in the system. 360.It Li KERN_FSYNC 361Return 1 if the POSIX 1003.1b File Synchronization Option is available 362on this system, 363otherwise 0. 364.It Li KERN_HOSTID 365Get or set the host id. 366.It Li KERN_HOSTNAME 367Get or set the hostname. 368.It Li KERN_IOV_MAX 369Return the maximum number of 370.Va iovec 371structures that a process has available for use with 372.Xr preadv 2 , 373.Xr pwritev 2 , 374.Xr readv 2 , 375.Xr recvmsg 2 , 376.Xr sendmsg 2 377and 378.Xr writev 2 . 379.It Li KERN_JOB_CONTROL 380Return 1 if job control is available on this system, otherwise 0. 381.It Li KERN_LINK_MAX 382The maximum file link count. 383.It Li KERN_LOGIN_NAME_MAX 384The size of the storage required for a login name, in bytes, 385including the terminating NUL. 386.It Li KERN_LOGSIGEXIT 387If this flag is non-zero, the kernel will 388.Xr log 9 389all process exits due to signals which create a 390.Xr core 5 391file, and whether the coredump was created. 392.It Li KERN_MAPPED_FILES 393Returns 1 if the POSIX 1003.1b Memory Mapped Files Option is available 394on this system, 395otherwise 0. 396.It Li KERN_MAXFILES 397The maximum number of open files that may be open in the system. 398.It Li KERN_MAXPARTITIONS 399The maximum number of partitions allowed per disk. 400.It Li KERN_MAXPROC 401The maximum number of simultaneous processes the system will allow. 402.It Li KERN_MAXVNODES 403The maximum number of vnodes available on the system. 404.It Li KERN_MAX_CANON 405The maximum number of bytes in terminal canonical input line. 406.It Li KERN_MAX_INPUT 407The minimum maximum number of bytes for which space is available in 408a terminal input queue. 409.It Li KERN_MEMLOCK 410Returns 1 if the POSIX 1003.1b Process Memory Locking Option is available 411on this system, 412otherwise 0. 413.It Li KERN_MEMLOCK_RANGE 414Returns 1 if the POSIX 1003.1b Range Memory Locking Option is available 415on this system, 416otherwise 0. 417.It Li KERN_MEMORY_PROTECTION 418Returns 1 if the POSIX 1003.1b Memory Protection Option is available 419on this system, 420otherwise 0. 421.It Li KERN_MSGBUFSIZE 422The maximum number of characters that the kernel message buffer can hold. 423.It Li KERN_NAME_MAX 424The maximum number of bytes in a file name. 425.It Li KERN_NGROUPS 426The maximum number of supplemental groups. 427.It Li KERN_NO_TRUNC 428Return 1 if file names longer than KERN_NAME_MAX are truncated. 429.It Li KERN_OSRELEASE 430The system release string. 431.It Li KERN_OSREV 432The system revision string. 433.It Li KERN_OSTYPE 434The system type string. 435.It Li KERN_PATH_MAX 436The maximum number of bytes in a pathname. 437.It Li KERN_PIPE_BUF 438The maximum number of bytes which will be written atomically to a pipe. 439.It Li KERN_POSIX1 440The version of ISO/IEC 9945 (POSIX 1003.1) with which the system 441attempts to comply. 442.It Li KERN_PROC 443Return the entire process table, or a subset of it. 444An array of 445.Va struct kinfo_proc 446structures is returned, 447whose size depends on the current number of such objects in the system. 448The third and fourth level names are as follows: 449.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 450.It Pa Third level name Fourth level is: 451.It KERN\_PROC\_ALL None 452.It KERN\_PROC\_PID A process ID 453.It KERN\_PROC\_PGRP A process group 454.It KERN\_PROC\_TTY A tty device 455.It KERN\_PROC\_UID A user ID 456.It KERN\_PROC\_RUID A real user ID 457.El 458.It Li KERN_PROF 459Return profiling information about the kernel. 460If the kernel is not compiled for profiling, 461attempts to retrieve any of the KERN_PROF values will 462fail with EOPNOTSUPP. 463The third level names for the string and integer profiling information 464is detailed below. 465The changeable column shows whether a process with appropriate 466privilege may change the value. 467.Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent 468.It Sy Pa Third level name Type Changeable 469.It GPROF\_STATE integer yes 470.It GPROF\_COUNT u_short[\|] yes 471.It GPROF\_FROMS u_short[\|] yes 472.It GPROF\_TOS struct tostruct yes 473.It GPROF\_GMONPARAM struct gmonparam no 474.El 475.Pp 476The variables are as follows: 477.Bl -tag -width "123456" 478.It Li GPROF_STATE 479Returns GMON_PROF_ON or GMON_PROF_OFF to show that profiling 480is running or stopped. 481.It Li GPROF_COUNT 482Array of statistical program counter counts. 483.It Li GPROF_FROMS 484Array indexed by program counter of call-from points. 485.It Li GPROF_TOS 486Array of 487.Va struct tostruct 488describing destination of calls and their counts. 489.It Li GPROF_GMONPARAM 490Structure giving the sizes of the above arrays. 491.El 492.It Li KERN_RAWPARTITION 493The raw partition of a disk (a == 0). 494.It Li KERN_SAVED_IDS 495Returns 1 if saved set-group and saved set-user ID is available. 496.It Li KERN_SECURELVL 497The system security level. 498This level may be raised by processes with appropriate privilege. 499It may only be lowered by process 1. 500.It Li KERN_SYNCHRONIZED_IO 501Returns 1 if the POSIX 1003.1b Synchronized I/O Option is available 502on this system, 503otherwise 0. 504.It Li KERN_SYSVMSG 505Returns 1 if System V style message queue functionality is available 506on this system, 507otherwise 0. 508.It Li KERN_SYSVSEM 509Returns 1 if System V style semaphore functionality is available 510on this system, 511otherwise 0. 512.It Li KERN_SYSVSHM 513Returns 1 if System V style share memory functionality is available 514on this system, 515otherwise 0. 516.It Li KERN_VDISABLE 517Returns the terminal character disabling value. 518.It Li KERN_VERSION 519The system version string. 520.It Li KERN_VNODE 521Return the entire vnode table. 522Note, the vnode table is not necessarily a consistent snapshot of 523the system. 524The returned data consists of an array whose size depends on the 525current number of such objects in the system. 526Each element of the array contains the kernel address of a vnode 527.Va struct vnode * 528followed by the vnode itself 529.Va struct vnode . 530.El 531.Sh CTL_MACHDEP 532The set of variables defined is architecture dependent. 533Most architectures define at least the following variables. 534.Bl -column "CONSOLE_DEVICEXXX" "integerXXX" -offset indent 535.It Sy Pa Second level name Type Changeable 536.It Li CPU_CONSDEV dev_t no 537.El 538.Sh CTL_NET 539The string and integer information available for the CTL_NET level 540is detailed below. 541The changeable column shows whether a process with appropriate 542privilege may change the value. 543.Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent 544.It Sy Pa Second level name Type Changeable 545.It PF\_ROUTE routing messages no 546.It PF\_INET IPv4 values yes 547.It PF\_INET6 IPv6 values yes 548.El 549.Pp 550.Bl -tag -width "123456" 551.It Li PF_ROUTE 552Return the entire routing table or a subset of it. 553The data is returned as a sequence of routing messages (see 554.Xr route 4 555for the header file, format and meaning). 556The length of each message is contained in the message header. 557.Pp 558The third level name is a protocol number, which is currently always 0. 559The fourth level name is an address family, which may be set to 0 to 560select all address families. 561The fifth and sixth level names are as follows: 562.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent 563.It Pa Fifth level name Sixth level is: 564.It NET\_RT\_FLAGS rtflags 565.It NET\_RT\_DUMP None 566.It NET\_RT\_IFLIST None 567.El 568.It Li PF_INET 569Get or set various global information about the IPv4 570.Pq Internet Protocol version 4 . 571The third level name is the protocol. 572The fourth level name is the variable name. 573The currently defined protocols and names are: 574.Bl -column "Protocol name" "Variable nameXX" "integer" "yes" -offset indent 575.It Pa Protocol name Variable name Type Changeable 576.It ip forwarding integer yes 577.It ip redirect integer yes 578.It ip ttl integer yes 579.It ip forwsrcrt integer yes 580.It ip directed-broadcast integer yes 581.It ip allowsrcrt integer yes 582.It ip subnetsarelocal integer yes 583.It ip mtudisc integer yes 584.It ip anonportmin integer yes 585.It ip anonportmax integer yes 586.It ip mtudisctimeout integer yes 587.It ip gifttl integer yes 588.It icmp errratelimit integer yes 589.It icmp maskrepl integer yes 590.It tcp rfc1323 integer yes 591.It tcp sendspace integer yes 592.It tcp recvspace integer yes 593.It tcp mssdflt integer yes 594.It tcp syn_cache_limit integer yes 595.It tcp syn_bucket_limit integer yes 596.It tcp syn_cache_interval integer yes 597.It tcp init_win integer yes 598.It tcp mss_ifmtu integer yes 599.It tcp sack integer yes 600.It tcp win_scale integer yes 601.It tcp timestamps integer yes 602.It tcp compat_42 integer yes 603.It tcp cwm integer yes 604.It tcp cwm_burstsize integer yes 605.It tcp ack_on_push integer yes 606.It tcp keepidle integer yes 607.It tcp keepintvl integer yes 608.It tcp keepcnt integer yes 609.It tcp slowhz integer no 610.It tcp newreno integer yes 611.It tcp log_refused integer yes 612.It tcp rstratelimit integer yes 613.It udp checksum integer yes 614.It udp sendspace integer yes 615.It udp recvspace integer yes 616.El 617.Pp 618The variables are as follows: 619.Bl -tag -width "123456" 620.It Li ip.forwarding 621Returns 1 when IP forwarding is enabled for the host, 622meaning that the host is acting as a router. 623.It Li ip.redirect 624Returns 1 when ICMP redirects may be sent by the host. 625This option is ignored unless the host is routing IP packets, 626and should normally be enabled on all systems. 627.It Li ip.ttl 628The maximum time-to-live (hop count) value for an IP packet sourced by 629the system. 630This value applies to normal transport protocols, not to ICMP. 631.It Li ip.forwsrcrt 632Returns 1 when forwarding of source-routed packets is enabled for 633the host. This value may only be changed if the kernel security 634level is less than 1. 635.It Li ip.directed-broadcast 636Returns 1 if directed broadcast behavior is enabled for the host. 637.It Li ip.allowsrcrt 638Returns 1 if the host accepts source routed packets. 639.It Li ip.subnetsarelocal 640Returns 1 if subnets are to be considered local addresses. 641.It Li ip.mtudisc 642Returns 1 if Path MTU Discovery is enabled. 643.It Li ip.anonportmin 644The lowest port number to use for TCP and UDP ephemeral port allocation. 645This cannot be set to less that 1024 or greater than 65535. 646.It Li ip.anonportmax 647The highest port number to use for TCP and UDP ephemeral port allocation. 648This cannot be set to less that 1024 or greater than 65535, and must 649be greater than 650.Li ip.anonportmin . 651.It Li ip.mtudisctimeout 652Returns the number of seconds in which a route added by the Path MTU 653Discovery engine will time out. When the route times out, the Path 654MTU Discovery engine will attempt to probe a larger path MTU. 655.It Li ip.gifttl 656The maximum time-to-live (hop count) value for an IPv4 packet generated by 657.Xr gif 4 658tunnel interface. 659.It Li icmp.errratelimit 660This variable specifies the minimum interval between ICMP error messages, 661in microseconds. 662.It Li icmp.maskrepl 663Returns 1 if ICMP network mask requests are to be answered. 664.It Li tcp.rfc1323 665Returns 1 if RFC1323 extensions to TCP are enabled. 666.It Li tcp.sendspace 667Returns the default TCP send buffer size. 668.It Li tcp.recvspace 669Returns the default TCP receive buffer size. 670.It Li tcp.mssdflt 671Returns the default maximum segment size both advertsized to the peer 672and to use when the peer does not advertize a maximum segment size to 673us during connection setup. Do not change this value unless you really 674know what you are doing. 675.It Li tcp.syn_cache_limit 676Returns the maximum number of entries allowed in the TCP compressed state 677engine. 678.It Li tcp.syn_bucket_limit 679Returns the maximum number of entries allowed per hash bucket in the TCP 680compressed state engine. 681.It Li tcp.syn_cache_interval 682Returns the TCP compressed state engine's timer interval. 683.It Li tcp.init_win 684Returns a value indicating the TCP initial congestion window. If this 685value is 0, an auto-tuning algorithm designed to use an initial window 686of approximately 4K bytes is in use. Otherwise, this value indicates 687a fixed number of packets. 688.It Li tcp.mss_ifmtu 689Returns 1 if TCP calculates the outgoing maximum segment size based on 690the MTU of the appropriate interface. Otherwise, it is calculated based on 691the greater of the MTU of the interface, and the largest (non-loopback) 692interface MTU on the system. 693.It Li tcp.sack 694Returns a value which determines the level of Selective Acknowledgement 695supported by TCP. If 2, we will transmit and receive SACK options. 696If 1, we will transmit SACK options, but ignore any SACK options received. 697If 0, SACK is disabled. 698.It Li tcp.win_scale 699If rfc1323 is enabled, a value of 1 indicates RFC1323 window scale options, 700for increasing the TCP window size, are enabled. 701.It Li tcp.timestamps 702If rfc1323 is enabled, a value of 1 indicates RFC1323 time stamp options, 703used for measuring TCP round trip times, are enabled. 704.It Li tcp.compat_42 705Returns 1 if work-arounds for bugs in the 4.2BSD TCP implementation are 706enabled. Use of this option is not recommended, although it may be 707required in order to communicate with extremely old TCP implementations. 708.It Li tcp.cwm 709Returns 1 if use of the Hughes/Touch/Heidemann Congestion Window Monitoring 710algorithm is enabled. This algorithm prevents line-rate bursts of packets 711that could otherwise occur when data begins flowing on an idle TCP 712connection. These line-rate bursts can contribute to network and router 713congestion. This can be particularly useful on World Wide Web servers 714which support HTTP/1.1, which has lingering connections. 715.It Li tcp.cwm_burstsize 716Returns the Congestion Window Monitoring allowed burst size, in terms 717of packet count. 718.It Li tcp.ack_on_push 719Returns 1 if TCP is to immediately transmit an ACK upon reception of 720a packet with PUSH set. This can avoid losing a round trip time in some 721rare situations, but has the caveat of potentially defeating TCP's delayed 722ACK algorithm. Use of this option is generally not recommended, but 723the variable exists in case your configuration really needs it. 724.It Li tcp.keepidle 725Time a connection must be idle before keepalives are sent (if keepalives 726are enabled for the connection). See also tcp.slowhz. 727.It Li tcp.keepintvl 728Time after a keepalive probe is sent until, in the absence of any response, 729another probe is sent. See also tcp.slowhz. 730.It Li tcp.keepcnt 731Number of keepalive probes sent before declaring a connection dead. If 732set to zero, there is no limit; keepalives will be sent until some kind of 733response is received from the peer. 734.It Li tcp.slowhz 735The units for tcp.keepidle and tcp.keepintvl; those variables are in ticks 736of a clock that ticks tcp.slowhz times per second. (That is, their values 737must be divided by the tcp.slowhz value to get times in seconds.) 738.It Li tcp.newreno 739Returns 1 if the use of J. Hoe's NewReno congestion control algorithm is 740enabled. This algorithm improves the start-up behavior of TCP connections. 741.It Li tcp.log_refused 742Returns 1 if refused TCP connections to the host will be logged. 743.It Li tcp.rstratelimit 744This variable specifies minimum interval, in microseconds, between RSTs 745sent in response to an incoming TCP packet with no corresponding listen 746or connected socket. 747.It Li udp.checksum 748Returns 1 when UDP checksums are being computed and checked. 749Disabling UDP checksums is strongly discouraged. 750.It Li udp.sendspace 751Returns the default UDP send buffer size. 752.It Li udp.recvspace 753Returns the default UDP receive buffer size. 754.El 755.Pp 756For variables net.*.ipsec, please refer to 757.Xr ipsec 4 . 758.It Li PF_INET6 759Get or set various global information about the IPv6 760.Pq Internet Protocol version 6 . 761The third level name is the protocol. 762The fourth level name is the variable name. 763The currently defined protocols and names are: 764.Bl -column "Protocol name" "Variable nameXX" "integer" "yes" -offset indent 765.It Pa Protocol name Variable name Type Changeable 766.It ip6 forwarding integer yes 767.It ip6 redirect integer yes 768.It ip6 hlim integer yes 769.It ip6 maxfragpackets integer yes 770.It ip6 accept_rtadv integer yes 771.It ip6 keepfaith integer yes 772.It ip6 log_interval integer yes 773.It ip6 hdrnestlimit integer yes 774.It ip6 dad_count integer yes 775.It ip6 auto_flowlabel integer yes 776.It ip6 defmcasthlim integer yes 777.It ip6 gif_hlim integer yes 778.It ip6 kame_version string no 779.It ip6 use_deprecated integer yes 780.It ip6 rr_prune integer yes 781.It ip6 bindv6only integer yes 782.It icmp6 rediraccept integer yes 783.It icmp6 redirtimeout integer yes 784.It icmp6 errratelimit integer yes 785.It icmp6 nd6_prune integer yes 786.It icmp6 nd6_delay integer yes 787.It icmp6 nd6_umaxtries integer yes 788.It icmp6 nd6_mmaxtries integer yes 789.It icmp6 nd6_useloopback integer yes 790.It icmp6 nodeinfo integer yes 791.It tcp6 mssdflt integer yes 792.It tcp6 do_rfc1323 integer yes 793.It tcp6 keepidle integer yes 794.It tcp6 keepinterval integer yes 795.It tcp6 keepcount integer yes 796.It tcp6 maxpersistidle integer yes 797.It tcp6 sendspace integer yes 798.It tcp6 recvspace integer yes 799.It tcp6 conntimeo integer yes 800.It tcp6 pmtu integer yes 801.It tcp6 pmtu_expire integer yes 802.It tcp6 pmtu_probe integer yes 803.It tcp6 43maxseg integer yes 804.It tcp6 syn_cache_limit integer yes 805.It tcp6 syn_bucket_limit integer yes 806.It tcp6 syn_cache_interval integer yes 807.It udp6 sendmax integer yes 808.It udp6 recvspace integer yes 809.El 810.Pp 811The variables are as follows: 812.Bl -tag -width "123456" 813.It Li ip6.forwarding 814Returns 1 when IPv6 forwarding is enabled for the node, 815meaning that the node is acting as a router. 816Returns 0 when IPv6 forwarding is disabled for the node, 817meaning that the node is acting as a host. 818IPv6 specification defines node behavior for 819.Dq router 820case and 821.Dq host 822case quite differently, and changing this variable during operation 823may cause serious trouble. 824It is recommended to configure the variable at bootstrap time, 825and bootstrap time only. 826.It Li ip6.redirect 827Returns 1 when ICMPv6 redirects may be sent by the node. 828This option is ignored unless the node is routing IP packets, 829and should normally be enabled on all systems. 830.It Li ip6.hlim 831The default hop limit value for an IPv6 unicast packet sourced by the node. 832This value applies to all the transport protocols on top of IPv6. 833There are APIs to override the value, as documented in 834.Xr ip6 4 . 835.It Li ip6.maxfragpackets 836The maximum number of fragmented packets the node will accept. 8370 means that the node will not accept any fragmented packets. 838-1 means that the node will accept as many fragmented packets as it receives. 839The flag is provided basically for avoiding possible DoS attacks. 840.It Li ip6.accept_rtadv 841If set to non-zero, the node will accept ICMPv6 router advertisement packets 842and autoconfigures address prefixes and default routers. 843The node must be a host 844.Pq not a router 845for the option to be meaningful. 846.It Li ip6.keepfaith 847If set to non-zero, it enables 848.Dq FAITH 849TCP relay IPv6-to-IPv4 translator code in the kernel. 850Refer 851.Xr faith 4 852and 853.Xr faithd 8 854for detail. 855.It Li ip6.log_interval 856The variable controls amount of logs generated by IPv6 packet 857forwarding engine, by seting interval between log output 858.Pq in seconds . 859.It Li ip6.hdrnestlimit 860The number of IPv6 extension headers permitted on incoming IPv6 packets. 861If set to 0, the node will accept as many extension headers as possible. 862.It Li ip6.dad_count 863The variable cofigures number of IPv6 DAD 864.Pq duplicated address detection 865probe packets. 866The packets will be generated when IPv6 interface addresses are configured. 867.It Li ip6.auto_flowlabel 868On connected transport protocol packets, 869fill IPv6 flowlabel field to help intermediate routers to identify packet flows. 870.It Li ip6.defmcasthlim 871The default hop limit value for an IPv6 multicast packet sourced by the node. 872This value applies to all the transport protocols on top of IPv6. 873There are APIs to override the value, as documented in 874.Xr ip6 4 . 875.It Li ip6.gif_hlim 876The maximum hop limit value for an IPv6 packet generated by 877.Xr gif 4 878tunnel interface. 879.It Li ip6.kame_version 880The string identifies the version of KAME IPv6 stack implemented in the kernel. 881.It Li ip6.use_deprecated 882The variable controls use of deprecated address, specified in RFC2462 5.5.4. 883.It Li ip6.rr_prune 884The variable specifies interval between IPv6 router renumbering prefix 885babysitting, in seconds. 886.It Li ip6.bindv6only 887The variable specifies initial value for 888.Dv IPV6_BINDV6ONLY 889socket option for 890.Dv AF_INET6 891socket. 892Please refer to 893.Xr ip6 4 894for detail. 895.It Li icmp6.rediraccept 896If set to non-zero, the host will accept ICMPv6 redirect packets. 897Note that IPv6 routers will never accept ICMPv6 redirect packets, 898and the variable is meaningful on IPv6 hosts 899.Pq non-router 900only. 901.It Li icmp6.redirtimeout 902The variable specifies lifetime of routing entries generated by incoming 903ICMPv6 redirect. 904.It Li icmp6.errratelimit 905The variable specifies minimum interval between ICMPv6 error messages, 906in microseconds. 907.It Li icmp6.nd6_prune 908The variable specifies interval between IPv6 neighbor cache babysitting, 909in seconds. 910.It Li icmp6.nd6_delay 911The variable specifies 912.Dv DELAY_FIRST_PROBE_TIME 913timing constant in IPv6 neighbor discovery specification 914.Pq RFC2461 , 915in seconds. 916.It Li icmp6.nd6_umaxtries 917The variable specifies 918.Dv MAX_UNICAST_SOLICIT 919constant in IPv6 neighbor discovery specification 920.Pq RFC2461 . 921.It Li icmp6.nd6_mmaxtries 922The variable specifies 923.Dv MAX_MULTICAST_SOLICIT 924constant in IPv6 neighbor discovery specification 925.Pq RFC2461 . 926.It Li icmp6.nd6_useloopback 927If set to non-zero, kernel IPv6 stack will use loopback interface for 928local traffic. 929.It Li icmp6.nodeinfo 930The variable enables, or disables, kernel support for 931ICMPv6 node information query/reply. 932.El 933.Pp 934Variables net.*.tcp6 and net.*.udp6 are identical to 935net.*.tcp and net.*.udp. 936Please refer to 937.Li PF_INET 938section above. 939For variables net.*.ipsec6, please refer to 940.Xr ipsec 4 . 941.El 942.Sh CTL_PROC 943The string and integer information available for the CTL_PROC 944is detailed below. 945The changeable column shows whether a process with appropriate 946privilege may change the value. 947These values are per-process, and as such may change from one process 948to another. When a process is created, the default values are inherited from 949its parent. When a set-user-ID or set-group-ID binary is executed, the 950value of PROC_PID_CORENAME is reset to the system default value. 951The second level name is either the magic value PROC_CURPROC, which 952points to the current process, or the PID of the target process. 953.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" "yes" -offset indent 954.It Sy Pa Third level name Type Changeable 955.It PROC\_PID\_CORENAME string yes 956.It PROC\_PID\_LIMIT node not applicable 957.El 958.Bl -tag -width "123456" 959.Pp 960.It Li PROC_PID_CORENAME 961The template used for the core dump file name (see 962.Xr core 5 963for details). The base name must either be 964.Nm core 965or end with the suffix ``.core'' (the super-user may set arbitrary names). By 966default it points to KERN_DEFCORENAME. 967.It Li PROC_PID_LIMIT 968Return resources limits, as defined for the 969.Xr getrlimit 2 970and 971.Xr setrlimit 2 972system calls. 973The fourth level name is one of: 974.Bl -tag -width PROC_PID_LIMIT_MEMLOCKAA 975.It Li PROC_PID_LIMIT_CPU 976The maximum amount of cpu time (in seconds) to be used by each process. 977.It Li PROC_PID_LIMIT_FSIZE 978The largest size (in bytes) file that may be created. 979.It Li PROC_PID_LIMIT_DATA 980The maximum size (in bytes) of the data segment for a process; 981this defines how far a program may extend its break with the 982.Xr sbrk 2 983system call. 984.It Li PROC_PID_LIMIT_STACK 985The maximum size (in bytes) of the stack segment for a process; 986this defines how far a program's stack segment may be extended. 987Stack extension is performed automatically by the system. 988.It Li PROC_PID_LIMIT_CORE 989The largest size (in bytes) 990.Pa core 991file that may be created. 992.It Li PROC_PID_LIMIT_RSS 993The maximum size (in bytes) to which a process's resident set size may 994grow. 995This imposes a limit on the amount of physical memory to be given to 996a process; if memory is tight, the system will prefer to take memory 997from processes that are exceeding their declared resident set size. 998.It Li PROC_PID_LIMIT_MEMLOCK 999The maximum size (in bytes) which a process may lock into memory 1000using the 1001.Xr mlock 2 1002function. 1003.It Li PROC_PID_LIMIT_NPROC 1004The maximum number of simultaneous processes for this user id. 1005.It Li PROC_PID_LIMIT_NOFILE 1006The maximum number of open files for this process. 1007.El 1008.Pp 1009The fifth level name is one of PROC_PID_LIMIT_TYPE_SOFT or 1010PROC_PID_LIMIT_TYPE_HARD, to select respectively the soft or hard limit. 1011Both are of type integer. 1012.El 1013.Pp 1014 1015.Sh CTL_USER 1016The string and integer information available for the CTL_USER level 1017is detailed below. 1018The changeable column shows whether a process with appropriate 1019privilege may change the value. 1020.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 1021.It Sy Pa Second level name Type Changeable 1022.It USER\_BC\_BASE\_MAX integer no 1023.It USER\_BC\_DIM\_MAX integer no 1024.It USER\_BC\_SCALE\_MAX integer no 1025.It USER\_BC\_STRING\_MAX integer no 1026.It USER\_COLL\_WEIGHTS\_MAX integer no 1027.It USER\_CS\_PATH string no 1028.It USER\_EXPR\_NEST\_MAX integer no 1029.It USER\_LINE\_MAX integer no 1030.It USER\_POSIX2\_CHAR\_TERM integer no 1031.It USER\_POSIX2\_C\_BIND integer no 1032.It USER\_POSIX2\_C\_DEV integer no 1033.It USER\_POSIX2\_FORT\_DEV integer no 1034.It USER\_POSIX2\_FORT\_RUN integer no 1035.It USER\_POSIX2\_LOCALEDEF integer no 1036.It USER\_POSIX2\_SW\_DEV integer no 1037.It USER\_POSIX2\_UPE integer no 1038.It USER\_POSIX2\_VERSION integer no 1039.It USER\_RE\_DUP\_MAX integer no 1040.It USER\_STREAM\_MAX integer no 1041.It USER\_TZNAME\_MAX integer no 1042.El 1043.Bl -tag -width "123456" 1044.Pp 1045.It Li USER_BC_BASE_MAX 1046The maximum ibase/obase values in the 1047.Xr bc 1 1048utility. 1049.It Li USER_BC_DIM_MAX 1050The maximum array size in the 1051.Xr bc 1 1052utility. 1053.It Li USER_BC_SCALE_MAX 1054The maximum scale value in the 1055.Xr bc 1 1056utility. 1057.It Li USER_BC_STRING_MAX 1058The maximum string length in the 1059.Xr bc 1 1060utility. 1061.It Li USER_COLL_WEIGHTS_MAX 1062The maximum number of weights that can be assigned to any entry of 1063the LC_COLLATE order keyword in the locale definition file. 1064.It Li USER_CS_PATH 1065Return a value for the 1066.Ev PATH 1067environment variable that finds all the standard utilities. 1068.It Li USER_EXPR_NEST_MAX 1069The maximum number of expressions that can be nested within 1070parenthesis by the 1071.Xr expr 1 1072utility. 1073.It Li USER_LINE_MAX 1074The maximum length in bytes of a text-processing utility's input 1075line. 1076.It Li USER_POSIX2_CHAR_TERM 1077Return 1 if the system supports at least one terminal type capable of 1078all operations described in POSIX 1003.2, otherwise 0. 1079.It Li USER_POSIX2_C_BIND 1080Return 1 if the system's C-language development facilities support the 1081C-Language Bindings Option, otherwise 0. 1082.It Li USER_POSIX2_C_DEV 1083Return 1 if the system supports the C-Language Development Utilities Option, 1084otherwise 0. 1085.It Li USER_POSIX2_FORT_DEV 1086Return 1 if the system supports the FORTRAN Development Utilities Option, 1087otherwise 0. 1088.It Li USER_POSIX2_FORT_RUN 1089Return 1 if the system supports the FORTRAN Runtime Utilities Option, 1090otherwise 0. 1091.It Li USER_POSIX2_LOCALEDEF 1092Return 1 if the system supports the creation of locales, otherwise 0. 1093.It Li USER_POSIX2_SW_DEV 1094Return 1 if the system supports the Software Development Utilities Option, 1095otherwise 0. 1096.It Li USER_POSIX2_UPE 1097Return 1 if the system supports the User Portability Utilities Option, 1098otherwise 0. 1099.It Li USER_POSIX2_VERSION 1100The version of POSIX 1003.2 with which the system attempts to comply. 1101.It Li USER_RE_DUP_MAX 1102The maximum number of repeated occurrences of a regular expression 1103permitted when using interval notation. 1104.ne 1i 1105.It Li USER_STREAM_MAX 1106The minimum maximum number of streams that a process may have open 1107at any one time. 1108.It Li USER_TZNAME_MAX 1109The minimum maximum number of types supported for the name of a 1110timezone. 1111.El 1112.Sh CTL_VM 1113The string and integer information available for the CTL_VM level 1114is detailed below. 1115The changeable column shows whether a process with appropriate 1116privilege may change the value. 1117.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 1118.It Sy Pa Second level name Type Changeable 1119.It VM\_LOADAVG struct loadavg no 1120.It VM\_METER struct vmtotal no 1121.El 1122.Pp 1123.Bl -tag -width "123456" 1124.It Li VM_LOADAVG 1125Return the load average history. 1126The returned data consists of a 1127.Va struct loadavg . 1128.It Li VM_METER 1129Return the system wide virtual memory statistics. 1130The returned data consists of a 1131.Va struct vmtotal . 1132.El 1133.Sh CTL_DDB 1134The integer information available for the CTL_DDB level is detailed below. 1135The changeable column shows whether a process with appropriate 1136privilege may change the value. 1137.Bl -column "DBCTL_TABSTOPSXXX" "integerXXX" -offset indent 1138.It Sy Pa Second level name Type Changeable 1139.It DBCTL\_RADIX integer yes 1140.It DBCTL\_MAXOFF integer yes 1141.It DBCTL\_LINES integer yes 1142.It DBCTL\_TABSTOPS integer yes 1143.It DBCTL\_ONPANIC integer yes 1144.It DBCTL\_FROMCONSOLE integer yes 1145.El 1146.Pp 1147.Bl -tag -width "123456" 1148.It Li DBCTL_RADIX 1149The input and output radix. 1150.It Li DBCTL_MAXOFF 1151The maximum symbol offset. 1152.It Li DBCTL_LINES 1153Number of display lines. 1154.It Li DBCTL_TABSTOPS 1155Tab width. 1156.It Li DBCTL_ONPANIC 1157If non-zero, DDB will be entered when the kernel panics. 1158.It Li DBCTL_FROMCONSOLE 1159If not zero, DDB may be entered by sending a break on a serial 1160console or by a special key sequence on a graphics console. 1161.El 1162.Pp 1163These MIB nodes are also available as variables from within the 1164DDB. See 1165.Xr ddb 4 1166for more details. 1167.Sh RETURN VALUES 1168If the call to 1169.Nm 1170is successful, the number of bytes copied out is returned. 1171Otherwise \-1 is returned and 1172.Va errno 1173is set appropriately. 1174.Sh ERRORS 1175The following errors may be reported: 1176.Bl -tag -width Er 1177.It Bq Er EFAULT 1178The buffer 1179.Fa name , 1180.Fa oldp , 1181.Fa newp , 1182or length pointer 1183.Fa oldlenp 1184contains an invalid address. 1185.It Bq Er EINVAL 1186The 1187.Fa name 1188array is less than two or greater than CTL_MAXNAME. 1189.It Bq Er EINVAL 1190A non-null 1191.Fa newp 1192is given and its specified length in 1193.Fa newlen 1194is too large or too small. 1195.It Bq Er ENOMEM 1196The length pointed to by 1197.Fa oldlenp 1198is too short to hold the requested value. 1199.It Bq Er ENOTDIR 1200The 1201.Fa name 1202array specifies an intermediate rather than terminal name. 1203.It Bq Er EOPNOTSUPP 1204The 1205.Fa name 1206array specifies a value that is unknown. 1207.It Bq Er EPERM 1208An attempt is made to set a read-only value. 1209.It Bq Er EPERM 1210A process without appropriate privilege attempts to set a value. 1211.It Bq Er EPERM 1212An attempt to change a value protected by the current kernel security 1213level is made. 1214.El 1215.Sh FILES 1216.Bl -tag -width <netinet/icmpXvar.h> -compact 1217.It Pa <sys/sysctl.h> 1218definitions for top level identifiers, second level kernel and hardware 1219identifiers, and user level identifiers 1220.It Pa <sys/socket.h> 1221definitions for second level network identifiers 1222.It Pa <sys/gmon.h> 1223definitions for third level profiling identifiers 1224.It Pa <vm/vm_param.h> 1225definitions for second level virtual memory identifiers 1226.It Pa <netinet/in.h> 1227definitions for third level IPv4/v6 identifiers and 1228fourth level IPv4/v6 identifiers 1229.It Pa <netinet/icmp_var.h> 1230definitions for fourth level ICMP identifiers 1231.It Pa <netinet/icmp6.h> 1232definitions for fourth level ICMPv6 identifiers 1233.It Pa <netinet/tcp_var.h> 1234definitions for fourth level TCP identifiers 1235.It Pa <netinet/udp_var.h> 1236definitions for fourth level UDP identifiers 1237.El 1238.Sh SEE ALSO 1239.Xr sysctl 8 , 1240.Xr ipsec 4 1241.Sh HISTORY 1242The 1243.Nm 1244function first appeared in 1245.Bx 4.4 . 1246