1.\" Copyright (c) 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" Redistribution and use in source and binary forms, with or without 5.\" modification, are permitted provided that the following conditions 6.\" are met: 7.\" 1. Redistributions of source code must retain the above copyright 8.\" notice, this list of conditions and the following disclaimer. 9.\" 2. Redistributions in binary form must reproduce the above copyright 10.\" notice, this list of conditions and the following disclaimer in the 11.\" documentation and/or other materials provided with the distribution. 12.\" 3. Neither the name of the University nor the names of its contributors 13.\" may be used to endorse or promote products derived from this software 14.\" without specific prior written permission. 15.\" 16.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 17.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 18.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 19.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 20.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 21.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 22.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 23.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 24.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 25.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26.\" SUCH DAMAGE. 27.\" 28.\" @(#)sysctl.3 8.4 (Berkeley) 5/9/95 29.\" $FreeBSD$ 30.\" 31.Dd October 18, 2021 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/sysctl.h 43.Ft int 44.Fn sysctl "const int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen" 45.Ft int 46.Fn sysctlbyname "const char *name" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen" 47.Ft int 48.Fn sysctlnametomib "const char *name" "int *mibp" "size_t *sizep" 49.Sh DESCRIPTION 50The 51.Fn sysctl 52function retrieves system information and allows processes with 53appropriate privileges to set system information. 54The information available from 55.Fn sysctl 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.Fn sysctl 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.Fn sysctl 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 79.Fn sysctlbyname 80function accepts an ASCII representation of the name and internally 81looks up the integer name vector. 82Apart from that, it behaves the same 83as the standard 84.Fn sysctl 85function. 86.Pp 87The information is copied into the buffer specified by 88.Fa oldp . 89The size of the buffer is given by the location specified by 90.Fa oldlenp 91before the call, 92and that location gives the amount of data copied after a successful call 93and after a call that returns with the error code 94.Er ENOMEM . 95If the amount of data available is greater 96than the size of the buffer supplied, 97the call supplies as much data as fits in the buffer provided 98and returns with the error code 99.Er ENOMEM . 100If the old value is not desired, 101.Fa oldp 102and 103.Fa oldlenp 104should be set to NULL. 105.Pp 106The size of the available data can be determined by calling 107.Fn sysctl 108with the 109.Dv NULL 110argument for 111.Fa oldp . 112The size of the available data will be returned in the location pointed to by 113.Fa oldlenp . 114For some operations, the amount of space may change often. 115For these operations, 116the system attempts to round up so that the returned size is 117large enough for a call to return the data shortly thereafter. 118.Pp 119To set a new value, 120.Fa newp 121is set to point to a buffer of length 122.Fa newlen 123from which the requested value is to be taken. 124If a new value is not to be set, 125.Fa newp 126should be set to NULL and 127.Fa newlen 128set to 0. 129.Pp 130The 131.Fn sysctlnametomib 132function accepts an ASCII representation of the name, 133looks up the integer name vector, 134and returns the numeric representation in the mib array pointed to by 135.Fa mibp . 136The number of elements in the mib array is given by the location specified by 137.Fa sizep 138before the call, 139and that location gives the number of entries copied after a successful call. 140The resulting 141.Fa mib 142and 143.Fa size 144may be used in subsequent 145.Fn sysctl 146calls to get the data associated with the requested ASCII name. 147This interface is intended for use by applications that want to 148repeatedly request the same variable (the 149.Fn sysctl 150function runs in about a third the time as the same request made via the 151.Fn sysctlbyname 152function). 153The 154.Fn sysctlnametomib 155function is also useful for fetching mib prefixes and then adding 156a final component. 157For example, to fetch process information 158for processes with pid's less than 100: 159.Pp 160.Bd -literal -offset indent -compact 161int i, mib[4]; 162size_t len; 163struct kinfo_proc kp; 164 165/* Fill out the first three components of the mib */ 166len = 4; 167sysctlnametomib("kern.proc.pid", mib, &len); 168 169/* Fetch and print entries for pid's < 100 */ 170for (i = 0; i < 100; i++) { 171 mib[3] = i; 172 len = sizeof(kp); 173 if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1) 174 perror("sysctl"); 175 else if (len > 0) 176 printkproc(&kp); 177} 178.Ed 179.Pp 180The top level names are defined with a CTL_ prefix in 181.In sys/sysctl.h , 182and are as follows. 183The next and subsequent levels down are found in the include files 184listed here, and described in separate sections below. 185.Bl -column CTLXMACHDEPXXX "Next Level NamesXXXXXX" -offset indent 186.It Sy Name Ta Sy Next Level Names Ta Sy Description 187.It Dv CTL_DEBUG Ta In sys/sysctl.h Ta Debugging 188.It Dv CTL_VFS Ta In sys/mount.h Ta File system 189.It Dv CTL_HW Ta In sys/sysctl.h Ta Generic CPU, I/O 190.It Dv CTL_KERN Ta In sys/sysctl.h Ta High kernel limits 191.It Dv CTL_MACHDEP Ta In sys/sysctl.h Ta Machine dependent 192.It Dv CTL_NET Ta In sys/socket.h Ta Networking 193.It Dv CTL_USER Ta In sys/sysctl.h Ta User-level 194.It Dv CTL_VM Ta In vm/vm_param.h Ta Virtual memory 195.El 196.Pp 197For example, the following retrieves the maximum number of processes allowed 198in the system: 199.Pp 200.Bd -literal -offset indent -compact 201int mib[2], maxproc; 202size_t len; 203 204mib[0] = CTL_KERN; 205mib[1] = KERN_MAXPROC; 206len = sizeof(maxproc); 207sysctl(mib, 2, &maxproc, &len, NULL, 0); 208.Ed 209.Pp 210To retrieve the standard search path for the system utilities: 211.Pp 212.Bd -literal -offset indent -compact 213int mib[2]; 214size_t len; 215char *p; 216 217mib[0] = CTL_USER; 218mib[1] = USER_CS_PATH; 219sysctl(mib, 2, NULL, &len, NULL, 0); 220p = malloc(len); 221sysctl(mib, 2, p, &len, NULL, 0); 222.Ed 223.Ss CTL_DEBUG 224The debugging variables vary from system to system. 225A debugging variable may be added or deleted without need to recompile 226.Fn sysctl 227to know about it. 228Each time it runs, 229.Fn sysctl 230gets the list of debugging variables from the kernel and 231displays their current values. 232The system defines twenty 233.Pq Vt "struct ctldebug" 234variables named 235.Va debug0 236through 237.Va debug19 . 238They are declared as separate variables so that they can be 239individually initialized at the location of their associated variable. 240The loader prevents multiple use of the same variable by issuing errors 241if a variable is initialized in more than one place. 242For example, to export the variable 243.Va dospecialcheck 244as a debugging variable, the following declaration would be used: 245.Pp 246.Bd -literal -offset indent -compact 247int dospecialcheck = 1; 248struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck }; 249.Ed 250.Ss CTL_VFS 251A distinguished second level name, VFS_GENERIC, 252is used to get general information about all file systems. 253One of its third level identifiers is VFS_MAXTYPENUM 254that gives the highest valid file system type number. 255Its other third level identifier is VFS_CONF that 256returns configuration information about the file system 257type given as a fourth level identifier (see 258.Xr getvfsbyname 3 259as an example of its use). 260The remaining second level identifiers are the 261file system type number returned by a 262.Xr statfs 2 263call or from VFS_CONF. 264The third level identifiers available for each file system 265are given in the header file that defines the mount 266argument structure for that file system. 267.Ss CTL_HW 268The string and integer information available for the CTL_HW level 269is detailed below. 270The changeable column shows whether a process with appropriate 271privilege may change the value. 272.Bl -column "Second Level Name" integerXXX Changeable -offset indent 273.It Sy Second Level Name Ta Sy Type Ta Sy Changeable 274.It Dv HW_MACHINE Ta string Ta no 275.It Dv HW_MODEL Ta string Ta no 276.It Dv HW_NCPU Ta integer Ta no 277.It Dv HW_BYTEORDER Ta integer Ta no 278.It Dv HW_PHYSMEM Ta integer Ta no 279.It Dv HW_USERMEM Ta integer Ta no 280.It Dv HW_PAGESIZE Ta integer Ta no 281.\".It Dv HW_DISKNAMES Ta integer Ta no 282.\".It Dv HW_DISKSTATS Ta integer Ta no 283.It Dv HW_FLOATINGPT Ta integer Ta no 284.It Dv HW_MACHINE_ARCH Ta string Ta no 285.It Dv HW_REALMEM Ta integer Ta no 286.It Dv HW_AVAILPAGES Ta integer Ta no 287.El 288.Bl -tag -width 6n 289.It Li HW_MACHINE 290The machine class. 291.It Li HW_MODEL 292The machine model 293.It Li HW_NCPU 294The number of cpus. 295.It Li HW_BYTEORDER 296The byteorder (4321 or 1234). 297.It Li HW_PHYSMEM 298Amount of physical memory (in bytes), minus the amount used by the kernel, 299pre-loaded modules, and (on x86) the dcons buffer. 300.It Li HW_USERMEM 301Amount of memory (in bytes) which is not wired. 302.It Li HW_PAGESIZE 303The software page size. 304.\".It Fa HW_DISKNAMES 305.\".It Fa HW_DISKSTATS 306.It Li HW_FLOATINGPT 307Nonzero if the floating point support is in hardware. 308.It Li HW_MACHINE_ARCH 309The machine dependent architecture type. 310.It Li HW_REALMEM 311Amount of memory (in bytes) reported by the firmware. 312That value is sometimes not sane; in that case, the kernel reports the max 313memory address instead. 314.It Li HW_AVAILPAGES 315The same value as 316.Li HW_PHYSMEM , 317measured in pages rather than bytes. 318.El 319.Ss CTL_KERN 320The string and integer information available for the CTL_KERN level 321is detailed below. 322The changeable column shows whether a process with appropriate 323privilege may change the value. 324The types of data currently available are process information, 325system vnodes, the open file entries, routing table entries, 326virtual memory statistics, load average history, and clock rate 327information. 328.Bl -column "KERNXMAXFILESPERPROCXXX" "struct clockrateXXX" -offset indent 329.It Sy Second Level Name Ta Sy Type Ta Sy Changeable 330.It Dv KERN_ARGMAX Ta integer Ta no 331.It Dv KERN_BOOTFILE Ta string Ta yes 332.It Dv KERN_BOOTTIME Ta struct timeval Ta no 333.It Dv KERN_CLOCKRATE Ta struct clockinfo Ta no 334.It Dv KERN_FILE Ta struct xfile Ta no 335.It Dv KERN_HOSTID Ta integer Ta yes 336.It Dv KERN_HOSTUUID Ta string Ta yes 337.It Dv KERN_HOSTNAME Ta string Ta yes 338.It Dv KERN_JOB_CONTROL Ta integer Ta no 339.It Dv KERN_MAXFILES Ta integer Ta yes 340.It Dv KERN_MAXFILESPERPROC Ta integer Ta yes 341.It Dv KERN_MAXPROC Ta integer Ta no 342.It Dv KERN_MAXPROCPERUID Ta integer Ta yes 343.It Dv KERN_MAXVNODES Ta integer Ta yes 344.It Dv KERN_NGROUPS Ta integer Ta no 345.It Dv KERN_NISDOMAINNAME Ta string Ta yes 346.It Dv KERN_OSRELDATE Ta integer Ta no 347.It Dv KERN_OSRELEASE Ta string Ta no 348.It Dv KERN_OSREV Ta integer Ta no 349.It Dv KERN_OSTYPE Ta string Ta no 350.It Dv KERN_POSIX1 Ta integer Ta no 351.It Dv KERN_PROC Ta node Ta not applicable 352.It Dv KERN_QUANTUM Ta integer Ta yes 353.It Dv KERN_SAVED_IDS Ta integer Ta no 354.It Dv KERN_SECURELVL Ta integer Ta raise only 355.It Dv KERN_UPDATEINTERVAL Ta integer Ta no 356.It Dv KERN_VERSION Ta string Ta no 357.It Dv KERN_VNODE Ta struct xvnode Ta no 358.El 359.Bl -tag -width 6n 360.It Li KERN_ARGMAX 361The maximum bytes of argument to 362.Xr execve 2 . 363.It Li KERN_BOOTFILE 364The full pathname of the file from which the kernel was loaded. 365.It Li KERN_BOOTTIME 366A 367.Va struct timeval 368structure is returned. 369This structure contains the time that the system was booted. 370.It Li KERN_CLOCKRATE 371A 372.Va struct clockinfo 373structure is returned. 374This structure contains the clock, statistics clock and profiling clock 375frequencies, the number of micro-seconds per hz tick and the skew rate. 376.It Li KERN_FILE 377Return the entire file table. 378The returned data consists of an array of 379.Va struct xfile , 380whose size depends on the current number of such objects in the system. 381.It Li KERN_HOSTID 382Get or set the host ID. 383.It Li KERN_HOSTUUID 384Get or set the host's universally unique identifier (UUID). 385.It Li KERN_HOSTNAME 386Get or set the hostname. 387.It Li KERN_JOB_CONTROL 388Return 1 if job control is available on this system, otherwise 0. 389.It Li KERN_MAXFILES 390The maximum number of files that may be open in the system. 391.It Li KERN_MAXFILESPERPROC 392The maximum number of files that may be open for a single process. 393This limit only applies to processes with an effective uid of nonzero 394at the time of the open request. 395Files that have already been opened are not affected if the limit 396or the effective uid is changed. 397.It Li KERN_MAXPROC 398The maximum number of concurrent processes the system will allow. 399.It Li KERN_MAXPROCPERUID 400The maximum number of concurrent processes the system will allow 401for a single effective uid. 402This limit only applies to processes with an effective uid of nonzero 403at the time of a fork request. 404Processes that have already been started are not affected if the limit 405is changed. 406.It Li KERN_MAXVNODES 407The maximum number of vnodes available on the system. 408.It Li KERN_NGROUPS 409The maximum number of supplemental groups. 410.It Li KERN_NISDOMAINNAME 411The name of the current YP/NIS domain. 412.It Li KERN_OSRELDATE 413The kernel release version in the format 414.Ar M Ns Ar mm Ns Ar R Ns Ar xx , 415where 416.Ar M 417is the major version, 418.Ar mm 419is the two digit minor version, 420.Ar R 421is 0 if release branch, otherwise 1, 422and 423.Ar xx 424is updated when the available APIs change. 425.Pp 426The userland release version is available from 427.In osreldate.h ; 428parse this file if you need to get the release version of 429the currently installed userland. 430.It Li KERN_OSRELEASE 431The system release string. 432.It Li KERN_OSREV 433The system revision string. 434.It Li KERN_OSTYPE 435The system type string. 436.It Li KERN_POSIX1 437The version of 438.St -p1003.1 439with which the system 440attempts to comply. 441.It Li KERN_PROC 442Return selected information about specific running processes. 443.Pp 444For the following names, an array of 445.Va struct kinfo_proc 446structures is returned, 447whose size depends on the current number of such objects in the system. 448.Bl -column "Third Level NameXXXXXX" "Fourth LevelXXXXXX" -offset indent 449.It Sy Third Level Name Ta Sy Fourth Level 450.It Dv KERN_PROC_ALL Ta None 451.It Dv KERN_PROC_PID Ta A process ID 452.It Dv KERN_PROC_PGRP Ta A process group 453.It Dv KERN_PROC_TTY Ta A tty device 454.It Dv KERN_PROC_UID Ta A user ID 455.It Dv KERN_PROC_RUID Ta A real user ID 456.El 457.Pp 458If the third level name is 459.Dv KERN_PROC_ARGS 460then the command line argument 461array is returned in a flattened form, i.e., zero-terminated arguments 462follow each other. 463The total size of array is returned. 464It is also possible for a process to set its own process title this way. 465If the third level name is 466.Dv KERN_PROC_PATHNAME , 467the path of the 468process' text file is stored. 469For 470.Dv KERN_PROC_PATHNAME , 471a process ID of 472.Li \-1 473implies the current process. 474.Bl -column "Third Level NameXXXXXX" "Fourth LevelXXXXXX" -offset indent 475.It Sy Third Level Name Ta Sy Fourth Level 476.It Dv KERN_PROC_ARGS Ta "A process ID" 477.It Dv KERN_PROC_PATHNAME Ta "A process ID" 478.El 479.It Li KERN_QUANTUM 480The maximum period of time, in microseconds, for which a process is allowed 481to run without being preempted if other processes are in the run queue. 482.It Li KERN_SAVED_IDS 483Returns 1 if saved set-group and saved set-user ID is available. 484.It Li KERN_SECURELVL 485The system security level. 486This level may be raised by processes with appropriate privilege. 487It may not be lowered. 488.It Li KERN_VERSION 489The system version string. 490.It Li KERN_VNODE 491Return the entire vnode table. 492Note, the vnode table is not necessarily a consistent snapshot of 493the system. 494The returned data consists of an array whose size depends on the 495current number of such objects in the system. 496Each element of the array consists of a 497.Va struct xvnode . 498.El 499.Ss CTL_NET 500The string and integer information available for the CTL_NET level 501is detailed below. 502The changeable column shows whether a process with appropriate 503privilege may change the value. 504.Bl -column "Second Level NameXXXXXX" "routing messagesXXX" -offset indent 505.It Sy Second Level Name Ta Sy Type Ta Sy Changeable 506.It Dv PF_ROUTE Ta routing messages Ta no 507.It Dv PF_INET Ta IPv4 values Ta yes 508.It Dv PF_INET6 Ta IPv6 values Ta yes 509.El 510.Bl -tag -width 6n 511.It Li PF_ROUTE 512Return the entire routing table or a subset of it. 513The data is returned as a sequence of routing messages (see 514.Xr route 4 515for the header file, format and meaning). 516The length of each message is contained in the message header. 517.Pp 518The third level name is a protocol number, which is currently always 0. 519The fourth level name is an address family, which may be set to 0 to 520select all address families. 521The fifth, sixth, and seventh level names are as follows: 522.Bl -column -offset indent "Fifth Level" "Sixth Level" "Seventh Level" 523.It Sy Fifth level Ta Sy Sixth Level Ta Sy Seventh Level 524.It Dv NET_RT_FLAGS Ta rtflags Ta None 525.It Dv NET_RT_DUMP Ta None Ta None or fib number 526.It Dv NET_RT_IFLIST Ta 0 or if_index Ta None 527.It Dv NET_RT_IFMALIST Ta 0 or if_index Ta None 528.It Dv NET_RT_IFLISTL Ta 0 or if_index Ta None 529.It Dv NET_RT_NHOPS Ta None Ta fib number 530.El 531.Pp 532The 533.Dv NET_RT_IFMALIST 534name returns information about multicast group memberships on all interfaces 535if 0 is specified, or for the interface specified by 536.Va if_index . 537.Pp 538The 539.Dv NET_RT_IFLISTL 540is like 541.Dv NET_RT_IFLIST , 542just returning message header structs with additional fields allowing the 543interface to be extended without breaking binary compatibility. 544The 545.Dv NET_RT_IFLISTL 546uses 'l' versions of the message header structures: 547.Va struct if_msghdrl 548and 549.Va struct ifa_msghdrl . 550.Pp 551.Dv NET_RT_NHOPS 552returns all nexthops for specified address family in given fib. 553.It Li PF_INET 554Get or set various global information about the IPv4 555(Internet Protocol version 4). 556The third level name is the protocol. 557The fourth level name is the variable name. 558The currently defined protocols and names are: 559.Bl -column ProtocolXX VariableXX TypeXX ChangeableXX 560.It Sy Protocol Ta Sy Variable Ta Sy Type Ta Sy Changeable 561.It icmp Ta bmcastecho Ta integer Ta yes 562.It icmp Ta maskrepl Ta integer Ta yes 563.It ip Ta forwarding Ta integer Ta yes 564.It ip Ta redirect Ta integer Ta yes 565.It ip Ta ttl Ta integer Ta yes 566.It udp Ta checksum Ta integer Ta yes 567.El 568.Pp 569The variables are as follows: 570.Bl -tag -width 6n 571.It Li icmp.bmcastecho 572Returns 1 if an ICMP echo request to a broadcast or multicast address is 573to be answered. 574.It Li icmp.maskrepl 575Returns 1 if ICMP network mask requests are to be answered. 576.It Li ip.forwarding 577Returns 1 when IP forwarding is enabled for the host, 578meaning that the host is acting as a router. 579.It Li ip.redirect 580Returns 1 when ICMP redirects may be sent by the host. 581This option is ignored unless the host is routing IP packets, 582and should normally be enabled on all systems. 583.It Li ip.ttl 584The maximum time-to-live (hop count) value for an IP packet sourced by 585the system. 586This value applies to normal transport protocols, not to ICMP. 587.It Li udp.checksum 588Returns 1 when UDP checksums are being computed and checked. 589Disabling UDP checksums is strongly discouraged. 590.Pp 591For variables net.inet.*.ipsec, please refer to 592.Xr ipsec 4 . 593.El 594.It Li PF_INET6 595Get or set various global information about the IPv6 596(Internet Protocol version 6). 597The third level name is the protocol. 598The fourth level name is the variable name. 599.Pp 600For variables net.inet6.* please refer to 601.Xr inet6 4 . 602For variables net.inet6.*.ipsec6, please refer to 603.Xr ipsec 4 . 604.El 605.Ss CTL_USER 606The string and integer information available for the CTL_USER level 607is detailed below. 608The changeable column shows whether a process with appropriate 609privilege may change the value. 610.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 611.It Sy Second Level Name Ta Sy Type Ta Sy Changeable 612.It Dv USER_BC_BASE_MAX Ta integer Ta no 613.It Dv USER_BC_DIM_MAX Ta integer Ta no 614.It Dv USER_BC_SCALE_MAX Ta integer Ta no 615.It Dv USER_BC_STRING_MAX Ta integer Ta no 616.It Dv USER_COLL_WEIGHTS_MAX Ta integer Ta no 617.It Dv USER_CS_PATH Ta string Ta no 618.It Dv USER_EXPR_NEST_MAX Ta integer Ta no 619.It Dv USER_LINE_MAX Ta integer Ta no 620.It Dv USER_LOCALBASE Ta string Ta no 621.It Dv USER_POSIX2_CHAR_TERM Ta integer Ta no 622.It Dv USER_POSIX2_C_BIND Ta integer Ta no 623.It Dv USER_POSIX2_C_DEV Ta integer Ta no 624.It Dv USER_POSIX2_FORT_DEV Ta integer Ta no 625.It Dv USER_POSIX2_FORT_RUN Ta integer Ta no 626.It Dv USER_POSIX2_LOCALEDEF Ta integer Ta no 627.It Dv USER_POSIX2_SW_DEV Ta integer Ta no 628.It Dv USER_POSIX2_UPE Ta integer Ta no 629.It Dv USER_POSIX2_VERSION Ta integer Ta no 630.It Dv USER_RE_DUP_MAX Ta integer Ta no 631.It Dv USER_STREAM_MAX Ta integer Ta no 632.It Dv USER_TZNAME_MAX Ta integer Ta no 633.El 634.Bl -tag -width 6n 635.It Li USER_BC_BASE_MAX 636The maximum ibase/obase values in the 637.Xr bc 1 638utility. 639.It Li USER_BC_DIM_MAX 640The maximum array size in the 641.Xr bc 1 642utility. 643.It Li USER_BC_SCALE_MAX 644The maximum scale value in the 645.Xr bc 1 646utility. 647.It Li USER_BC_STRING_MAX 648The maximum string length in the 649.Xr bc 1 650utility. 651.It Li USER_COLL_WEIGHTS_MAX 652The maximum number of weights that can be assigned to any entry of 653the LC_COLLATE order keyword in the locale definition file. 654.It Li USER_CS_PATH 655Return a value for the 656.Ev PATH 657environment variable that finds all the standard utilities. 658.It Li USER_EXPR_NEST_MAX 659The maximum number of expressions that can be nested within 660parenthesis by the 661.Xr expr 1 662utility. 663.It Li USER_LINE_MAX 664The maximum length in bytes of a text-processing utility's input 665line. 666.It Li USER_LOCALBASE 667Return the value of localbase that has been compiled into system utilities 668that need to have access to resources provided by a port or package. 669.It Li USER_POSIX2_CHAR_TERM 670Return 1 if the system supports at least one terminal type capable of 671all operations described in 672.St -p1003.2 , 673otherwise 0. 674.It Li USER_POSIX2_C_BIND 675Return 1 if the system's C-language development facilities support the 676C-Language Bindings Option, otherwise 0. 677.It Li USER_POSIX2_C_DEV 678Return 1 if the system supports the C-Language Development Utilities Option, 679otherwise 0. 680.It Li USER_POSIX2_FORT_DEV 681Return 1 if the system supports the FORTRAN Development Utilities Option, 682otherwise 0. 683.It Li USER_POSIX2_FORT_RUN 684Return 1 if the system supports the FORTRAN Runtime Utilities Option, 685otherwise 0. 686.It Li USER_POSIX2_LOCALEDEF 687Return 1 if the system supports the creation of locales, otherwise 0. 688.It Li USER_POSIX2_SW_DEV 689Return 1 if the system supports the Software Development Utilities Option, 690otherwise 0. 691.It Li USER_POSIX2_UPE 692Return 1 if the system supports the User Portability Utilities Option, 693otherwise 0. 694.It Li USER_POSIX2_VERSION 695The version of 696.St -p1003.2 697with which the system attempts to comply. 698.It Li USER_RE_DUP_MAX 699The maximum number of repeated occurrences of a regular expression 700permitted when using interval notation. 701.It Li USER_STREAM_MAX 702The minimum maximum number of streams that a process may have open 703at any one time. 704.It Li USER_TZNAME_MAX 705The minimum maximum number of types supported for the name of a 706timezone. 707.El 708.Ss CTL_VM 709The string and integer information available for the CTL_VM level 710is detailed below. 711The changeable column shows whether a process with appropriate 712privilege may change the value. 713.Bl -column "Second Level NameXXXXXX" "struct loadavgXXX" -offset indent 714.It Sy Second Level Name Ta Sy Type Ta Sy Changeable 715.It Dv VM_LOADAVG Ta struct loadavg Ta no 716.It Dv VM_TOTAL Ta struct vmtotal Ta no 717.It Dv VM_SWAPPING_ENABLED Ta integer Ta maybe 718.It Dv VM_V_FREE_MIN Ta integer Ta yes 719.It Dv VM_V_FREE_RESERVED Ta integer Ta yes 720.It Dv VM_V_FREE_TARGET Ta integer Ta yes 721.It Dv VM_V_INACTIVE_TARGET Ta integer Ta yes 722.It Dv VM_V_PAGEOUT_FREE_MIN Ta integer Ta yes 723.It Dv VM_OVERCOMMIT Ta integer Ta yes 724.El 725.Bl -tag -width 6n 726.It Li VM_LOADAVG 727Return the load average history. 728The returned data consists of a 729.Va struct loadavg . 730.It Li VM_TOTAL 731Return the system wide virtual memory statistics. 732The returned data consists of a 733.Va struct vmtotal . 734.It Li VM_SWAPPING_ENABLED 7351 if process swapping is enabled or 0 if disabled. 736This variable is 737permanently set to 0 if the kernel was built with swapping disabled. 738.It Li VM_V_FREE_MIN 739Minimum amount of memory (cache memory plus free memory) 740required to be available before a process waiting on memory will be 741awakened. 742.It Li VM_V_FREE_RESERVED 743Processes will awaken the pageout daemon and wait for memory if the 744number of free and cached pages drops below this value. 745.It Li VM_V_FREE_TARGET 746The total amount of free memory (including cache memory) that the 747pageout daemon tries to maintain. 748.It Li VM_V_INACTIVE_TARGET 749The desired number of inactive pages that the pageout daemon should 750achieve when it runs. 751Inactive pages can be quickly inserted into 752process address space when needed. 753.It Li VM_V_PAGEOUT_FREE_MIN 754If the amount of free and cache memory falls below this value, the 755pageout daemon will enter "memory conserving mode" to avoid deadlock. 756.It Li VM_OVERCOMMIT 757Overcommit behaviour, as described in 758.Xr tuning 7 . 759.El 760.Sh RETURN VALUES 761.Rv -std 762.Sh FILES 763.Bl -tag -width <netinet/icmpXvar.h> -compact 764.It In sys/sysctl.h 765definitions for top level identifiers, second level kernel and hardware 766identifiers, and user level identifiers 767.It In sys/socket.h 768definitions for second level network identifiers 769.It In sys/gmon.h 770definitions for third level profiling identifiers 771.It In vm/vm_param.h 772definitions for second level virtual memory identifiers 773.It In netinet/in.h 774definitions for third level IPv4/IPv6 identifiers and 775fourth level IPv4/v6 identifiers 776.It In netinet/icmp_var.h 777definitions for fourth level ICMP identifiers 778.It In netinet/icmp6.h 779definitions for fourth level ICMPv6 identifiers 780.It In netinet/udp_var.h 781definitions for fourth level UDP identifiers 782.El 783.Sh ERRORS 784The following errors may be reported: 785.Bl -tag -width Er 786.It Bq Er EFAULT 787The buffer 788.Fa name , 789.Fa oldp , 790.Fa newp , 791or length pointer 792.Fa oldlenp 793contains an invalid address. 794.It Bq Er EINVAL 795The 796.Fa name 797array is less than two or greater than CTL_MAXNAME. 798.It Bq Er EINVAL 799A non-null 800.Fa newp 801is given and its specified length in 802.Fa newlen 803is too large or too small. 804.It Bq Er ENOMEM 805The length pointed to by 806.Fa oldlenp 807is too short to hold the requested value. 808.It Bq Er ENOMEM 809The smaller of either the length pointed to by 810.Fa oldlenp 811or the estimated size of the returned data exceeds the 812system limit on locked memory. 813.It Bq Er ENOMEM 814Locking the buffer 815.Fa oldp , 816or a portion of the buffer if the estimated size of the data 817to be returned is smaller, 818would cause the process to exceed its per-process locked memory limit. 819.It Bq Er ENOTDIR 820The 821.Fa name 822array specifies an intermediate rather than terminal name. 823.It Bq Er EISDIR 824The 825.Fa name 826array specifies a terminal name, but the actual name is not terminal. 827.It Bq Er ENOENT 828The 829.Fa name 830array specifies a value that is unknown. 831.It Bq Er EPERM 832An attempt is made to set a read-only value. 833.It Bq Er EPERM 834A process without appropriate privilege attempts to set a value. 835.El 836.Sh SEE ALSO 837.Xr confstr 3 , 838.Xr kvm 3 , 839.Xr sysconf 3 , 840.Xr sysctl 8 841.Sh HISTORY 842The 843.Fn sysctl 844function first appeared in 845.Bx 4.4 . 846