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. All advertising materials mentioning features or use of this software 13.\" must display the following acknowledgement: 14.\" This product includes software developed by the University of 15.\" California, Berkeley and its contributors. 16.\" 4. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)sysctl.3 8.4 (Berkeley) 5/9/95 33.\" $FreeBSD: src/lib/libc/gen/sysctl.3,v 1.33.2.13 2002/04/07 04:57:14 dd Exp $ 34.\" $DragonFly: src/lib/libc/gen/sysctl.3,v 1.9 2007/10/26 08:22:00 swildner Exp $ 35.\" 36.Dd January 23, 2001 37.Dt SYSCTL 3 38.Os 39.Sh NAME 40.Nm sysctl , 41.Nm sysctlbyname , 42.Nm sysctlnametomib 43.Nd get or set system information 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In sys/types.h 48.In sys/sysctl.h 49.Ft int 50.Fn sysctl "int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" 51.Ft int 52.Fn sysctlbyname "const char *name" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" 53.Ft int 54.Fn sysctlnametomib "const char *name" "int *mibp" "size_t *sizep" 55.Sh DESCRIPTION 56The 57.Fn sysctl 58function retrieves system information and allows processes with 59appropriate privileges to set system information. 60The information available from 61.Fn sysctl 62consists of integers, strings, and tables. 63Information may be retrieved and set from the command interface 64using the 65.Xr sysctl 8 66utility. 67.Pp 68Unless explicitly noted below, 69.Fn sysctl 70returns a consistent snapshot of the data requested. 71Consistency is obtained by locking the destination 72buffer into memory so that the data may be copied out without blocking. 73Calls to 74.Fn sysctl 75are serialized to avoid deadlock. 76.Pp 77The state is described using a ``Management Information Base'' (MIB) 78style name, listed in 79.Fa name , 80which is a 81.Fa namelen 82length array of integers. 83.Pp 84The 85.Fn sysctlbyname 86function accepts an ASCII representation of the name and internally 87looks up the integer name vector. Apart from that, it behaves the same 88as the standard 89.Fn sysctl 90function. 91.Pp 92The information is copied into the buffer specified by 93.Fa oldp . 94The size of the buffer is given by the location specified by 95.Fa oldlenp 96before the call, 97and that location gives the amount of data copied after a successful call 98and after a call that returns with the error code 99.Er ENOMEM . 100If the amount of data available is greater 101than the size of the buffer supplied, 102the call supplies as much data as fits in the buffer provided 103and returns with the error code 104.Er ENOMEM . 105If the old value is not desired, 106.Fa oldp 107and 108.Fa oldlenp 109should be set to NULL. 110.Pp 111The size of the available data can be determined by calling 112.Fn sysctl 113with a NULL parameter for 114.Fa oldp . 115The size of the available data will be returned in the location pointed to by 116.Fa oldlenp . 117For some operations, the amount of space may change often. 118For these operations, 119the system attempts to round up so that the returned size is 120large enough for a call to return the data shortly thereafter. 121.Pp 122To set a new value, 123.Fa newp 124is set to point to a buffer of length 125.Fa newlen 126from which the requested value is to be taken. 127If a new value is not to be set, 128.Fa newp 129should be set to NULL and 130.Fa newlen 131set to 0. 132.Pp 133The 134.Fn sysctlnametomib 135function accepts an ASCII representation of the name, 136looks up the integer name vector, 137and returns the numeric representation in the mib array pointed to by 138.Fa mibp . 139The number of elements in the mib array is given by the location specified by 140.Fa sizep 141before the call, 142and that location gives the number of entries copied after a successful call. 143The resulting 144.Fa mib 145and 146.Fa size 147may be used in subsequent 148.Fn sysctl 149calls to get the data associated with the requested ASCII name. 150This interface is intended for use by applications that want to 151repeatedly request the same variable (the 152.Fn sysctl 153function runs in about a third the time as the same request made via the 154.Fn sysctlbyname 155function). 156The 157.Fn sysctlnametomib 158function is also useful for fetching mib prefixes and then adding 159a final component. 160For example, to fetch process information 161for processes with pid's less than 100: 162.Pp 163.Bd -literal -offset indent -compact 164int i, mib[4]; 165size_t len; 166struct kinfo_proc kp; 167 168/* Fill out the first three components of the mib */ 169len = 4; 170sysctlnametomib("kern.proc.pid", mib, &len); 171 172/* Fetch and print entries for pid's < 100 */ 173for (i = 0; i < 100; i++) { 174 mib[3] = i; 175 len = sizeof(kp); 176 if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1) 177 perror("sysctl"); 178 else if (len > 0) 179 printkproc(&kp); 180} 181.Ed 182.Pp 183The top level names are defined with a CTL_ prefix in 184.In sys/sysctl.h , 185and are as follows. 186The next and subsequent levels down are found in the include files 187listed here, and described in separate sections below. 188.Pp 189.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent 190.It Sy "Name Next level names Description" 191.It "CTL\_DEBUG sys/sysctl.h Debugging" 192.It "CTL\_VFS sys/mount.h Filesystem" 193.It "CTL\_HW sys/sysctl.h Generic CPU, I/O" 194.It "CTL\_KERN sys/sysctl.h High kernel limits" 195.It "CTL\_MACHDEP sys/sysctl.h Machine dependent" 196.It "CTL\_NET sys/socket.h Networking" 197.It "CTL\_USER sys/sysctl.h User-level" 198.It "CTL\_VM vm/vm_param.h Virtual memory" 199.El 200.Pp 201For example, the following retrieves the maximum number of processes allowed 202in the system: 203.Pp 204.Bd -literal -offset indent -compact 205int mib[2], maxproc; 206size_t len; 207 208mib[0] = CTL_KERN; 209mib[1] = KERN_MAXPROC; 210len = sizeof(maxproc); 211sysctl(mib, 2, &maxproc, &len, NULL, 0); 212.Ed 213.Pp 214To retrieve the standard search path for the system utilities: 215.Pp 216.Bd -literal -offset indent -compact 217int mib[2]; 218size_t len; 219char *p; 220 221mib[0] = CTL_USER; 222mib[1] = USER_CS_PATH; 223sysctl(mib, 2, NULL, &len, NULL, 0); 224p = malloc(len); 225sysctl(mib, 2, p, &len, NULL, 0); 226.Ed 227.Ss CTL_DEBUG 228The debugging variables vary from system to system. 229A debugging variable may be added or deleted without need to recompile 230.Fn sysctl 231to know about it. 232Each time it runs, 233.Fn sysctl 234gets the list of debugging variables from the kernel and 235displays their current values. 236The system defines twenty 237.Ns ( Va struct ctldebug ) 238variables named 239.Nm debug0 240through 241.Nm debug19 . 242They are declared as separate variables so that they can be 243individually initialized at the location of their associated variable. 244The loader prevents multiple use of the same variable by issuing errors 245if a variable is initialized in more than one place. 246For example, to export the variable 247.Nm dospecialcheck 248as a debugging variable, the following declaration would be used: 249.Bd -literal -offset indent -compact 250int dospecialcheck = 1; 251struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck }; 252.Ed 253.Ss CTL_VFS 254A distinguished second level name, VFS_GENERIC, 255is used to get general information about all filesystems. 256One of its third level identifiers is VFS_MAXTYPENUM 257that gives the highest valid filesystem type number. 258Its other third level identifier is VFS_CONF that 259returns configuration information about the filesystem 260type given as a fourth level identifier (see 261.Xr getvfsbyname 3 262as an example of its use). 263The remaining second level identifiers are the 264filesystem type number returned by a 265.Xr statfs 2 266call or from VFS_CONF. 267The third level identifiers available for each filesystem 268are given in the header file that defines the mount 269argument structure for that filesystem. 270.Ss CTL_HW 271The string and integer information available for the CTL_HW level 272is detailed below. 273The changeable column shows whether a process with appropriate 274privilege may change the value. 275.Bl -column "Second level nameXXXXXX" integerXXX -offset indent 276.It Sy "Second level name Type Changeable" 277.It "HW\_MACHINE string no" 278.It "HW\_MODEL string no" 279.It "HW\_NCPU integer no" 280.It "HW\_BYTEORDER integer no" 281.It "HW\_PHYSMEM integer no" 282.It "HW\_USERMEM integer no" 283.It "HW\_PAGESIZE integer no" 284.It "HW\_FLOATINGPOINT integer no" 285.It "HW\_MACHINE\_ARCH string no" 286.\".It "HW\_DISKNAMES integer no" 287.\".It "HW\_DISKSTATS integer no" 288.It "HW_SENSORS node not applicable" 289.El 290.Pp 291.Bl -tag -width 6n 292.It Li HW_MACHINE 293The machine class. 294.It Li HW_MODEL 295The machine model 296.It Li HW_NCPU 297The number of cpus. 298.It Li HW_BYTEORDER 299The byteorder (4,321, or 1,234). 300.It Li HW_PHYSMEM 301The bytes of physical memory. 302.It Li HW_USERMEM 303The bytes of non-kernel memory. 304.It Li HW_PAGESIZE 305The software page size. 306.It Li HW_FLOATINGPOINT 307Nonzero if the floating point support is in hardware. 308.It Li HW_MACHINE_ARCH 309The machine dependent architecture type. 310.\".It Fa HW_DISKNAMES 311.\".It Fa HW_DISKSTATS 312.It Li HW_SENSORS 313Third level comprises an array of 314.Vt "struct sensordev" 315structures containing information about devices 316that may attach hardware monitoring sensors. 317.Pp 318Third, fourth and fifth levels together comprise an array of 319.Vt "struct sensor" 320structures containing snapshot readings of hardware monitoring sensors. 321In such usage, third level indicates the numerical representation 322of the sensor device name to which the sensor is attached 323(device's 324.Va xname 325and number shall be matched with the help of 326.Vt "struct sensordev" 327structure above), 328fourth level indicates sensor type and 329fifth level is an ordinal sensor number (unique to 330the specified sensor type on the specified sensor device). 331.Pp 332The 333.Vt sensordev 334and 335.Vt sensor 336structures 337and 338.Vt sensor_type 339enumeration 340are defined in 341.In sys/sensors.h . 342.El 343.Ss CTL_KERN 344The string and integer information available for the CTL_KERN level 345is detailed below. 346The changeable column shows whether a process with appropriate 347privilege may change the value. 348The types of data currently available are process information, 349system vnodes, the open file entries, routing table entries, 350virtual memory statistics, load average history, and clock rate 351information. 352.Bl -column "KERNXMAXPOSIXLOCKSPERUIDXXX" "struct clockrateXXX" -offset indent 353.It Sy "Second level name Type Changeable" 354.It "KERN\_ARGMAX integer no" 355.It "KERN\_BOOTFILE string yes" 356.It "KERN\_BOOTTIME struct timeval no" 357.It "KERN\_CLOCKRATE struct clockinfo no" 358.It "KERN\_FILE struct file no" 359.It "KERN\_HOSTID integer yes" 360.It "KERN\_HOSTNAME string yes" 361.It "KERN\_JOB\_CONTROL integer no" 362.It "KERN\_MAXFILES integer yes" 363.It "KERN\_MAXFILESPERPROC integer yes" 364.It "KERN\_MAXPOSIXLOCKSPERUID integer yes" 365.It "KERN\_MAXPROC integer no" 366.It "KERN\_MAXPROCPERUID integer yes" 367.It "KERN\_MAXVNODES integer yes" 368.It "KERN\_NGROUPS integer no" 369.It "KERN\_NISDOMAINNAME string yes" 370.It "KERN\_OSRELDATE integer no" 371.It "KERN\_OSRELEASE string no" 372.It "KERN\_OSREV integer no" 373.It "KERN\_OSTYPE string no" 374.It "KERN\_POSIX1 integer no" 375.It "KERN\_PROC struct proc no" 376.It "KERN\_PROF node not applicable" 377.It "KERN\_QUANTUM integer yes" 378.It "KERN\_SAVED\_IDS integer no" 379.It "KERN\_SECURELVL integer raise only" 380.It "KERN\_UPDATEINTERVAL integer no" 381.It "KERN\_VERSION string no" 382.It "KERN\_VNODE struct vnode no" 383.El 384.Pp 385.Bl -tag -width 6n 386.It Li KERN_ARGMAX 387The maximum bytes of argument to 388.Xr execve 2 . 389.It Li KERN_BOOTFILE 390The full pathname of the file from which the kernel was loaded. 391.It Li KERN_BOOTTIME 392A 393.Va struct timeval 394structure is returned. 395This structure contains the time that the system was booted. 396.It Li KERN_CLOCKRATE 397A 398.Va struct clockinfo 399structure is returned. 400This structure contains the clock, statistics clock and profiling clock 401frequencies, the number of micro-seconds per hz tick and the skew rate. 402.It Li KERN_FILE 403Return the entire file table. 404The returned data consists of a single 405.Va struct filehead 406followed by an array of 407.Va struct file , 408whose size depends on the current number of such objects in the system. 409.It Li KERN_HOSTID 410Get or set the host id. 411.It Li KERN_HOSTNAME 412Get or set the hostname. 413.It Li KERN_JOB_CONTROL 414Return 1 if job control is available on this system, otherwise 0. 415.It Li KERN_MAXFILES 416The maximum number of files that may be open in the system. 417.It Li KERN_MAXFILESPERPROC 418The maximum number of files that may be open for a single process. 419This limit only applies to processes with an effective uid of nonzero 420at the time of the open request. 421Files that have already been opened are not affected if the limit 422or the effective uid is changed. 423.It Li KERN_MAXPROC 424The maximum number of concurrent processes the system will allow. 425.It Li KERN_MAXPROCPERUID 426The maximum number of concurrent processes the system will allow 427for a single effective uid. 428This limit only applies to processes with an effective uid of nonzero 429at the time of a fork request. 430Processes that have already been started are not affected if the limit 431is changed. 432.It Li KERN_MAXVNODES 433The maximum number of vnodes available on the system. 434.It Li KERN_NGROUPS 435The maximum number of supplemental groups. 436.It Li KERN_NISDOMAINNAME 437The name of the current YP/NIS domain. 438.It Li KERN_OSRELDATE 439The system release date in YYYYMM format 440(January 1996 is encoded as 199601). 441.It Li KERN_OSRELEASE 442The system release string. 443.It Li KERN_OSREV 444The system revision string. 445.It Li KERN_OSTYPE 446The system type string. 447.It Li KERN_POSIX1 448The version of 449.St -p1003.1 450with which the system 451attempts to comply. 452.It Li KERN_PROC 453Return the entire process table, or a subset of it. 454An array of 455.Va struct kinfo_proc 456structures is returned, 457whose size depends on the current number of such objects in the system. 458The third and fourth level names are as follows: 459.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 460.It "Third level name Fourth level is:" 461.It "KERN\_PROC\_ALL None" 462.It "KERN\_PROC\_PID A process ID" 463.It "KERN\_PROC\_PGRP A process group" 464.It "KERN\_PROC\_TTY A tty device" 465.It "KERN\_PROC\_UID A user ID" 466.It "KERN\_PROC\_RUID A real user ID" 467.El 468.Pp 469Adding the flag 470.Li KERN_PROC_FLAG_LWP 471to the third level name signals that information about all 472light weight processes of the selected processes should be returned. 473.It Li KERN_PROF 474Return profiling information about the kernel. 475If the kernel is not compiled for profiling, 476attempts to retrieve any of the KERN_PROF values will 477fail with 478.Er ENOENT . 479The third level names for the string and integer profiling information 480is detailed below. 481The changeable column shows whether a process with appropriate 482privilege may change the value. 483.Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent 484.It Sy "Third level name Type Changeable" 485.It "GPROF\_STATE integer yes" 486.It "GPROF\_COUNT u_short[\|] yes" 487.It "GPROF\_FROMS u_short[\|] yes" 488.It "GPROF\_TOS struct tostruct yes" 489.It "GPROF\_GMONPARAM struct gmonparam no" 490.El 491.Pp 492The variables are as follows: 493.Bl -tag -width 6n 494.It Li GPROF_STATE 495Returns GMON_PROF_ON or GMON_PROF_OFF to show that profiling 496is running or stopped. 497.It Li GPROF_COUNT 498Array of statistical program counter counts. 499.It Li GPROF_FROMS 500Array indexed by program counter of call-from points. 501.It Li GPROF_TOS 502Array of 503.Va struct tostruct 504describing destination of calls and their counts. 505.It Li GPROF_GMONPARAM 506Structure giving the sizes of the above arrays. 507.El 508.It Li KERN_QUANTUM 509The maximum period of time, in microseconds, for which a process is allowed 510to run without being preempted if other processes are in the run queue. 511.It Li KERN_SAVED_IDS 512Returns 1 if saved set-group and saved set-user ID is available. 513.It Li KERN_SECURELVL 514The system security level. 515This level may be raised by processes with appropriate privilege. 516It may not be lowered. 517.It Li KERN_VERSION 518The system version string. 519.It Li KERN_VNODE 520Return the entire vnode table. 521Note, the vnode table is not necessarily a consistent snapshot of 522the system. 523The returned data consists of an array whose size depends on the 524current number of such objects in the system. 525Each element of the array contains the kernel address of a vnode 526.Va struct vnode * 527followed by the vnode itself 528.Va struct vnode . 529.El 530.Ss CTL_MACHDEP 531The set of variables defined is architecture dependent. 532The following variables are defined for the i386 architecture. 533.Bl -column "CONSOLE_DEVICEXXX" "struct bootinfoXXX" -offset indent 534.It Sy "Second level name Type Changeable" 535.It Li "CPU_CONSDEV dev_t no" 536.It Li "CPU_ADJKERNTZ int yes" 537.It Li "CPU_DISRTCSET int yes" 538.It Li "CPU_BOOTINFO struct bootinfo no" 539.It Li "CPU_WALLCLOCK int yes" 540.El 541.Ss CTL_NET 542The string and integer information available for the CTL_NET level 543is detailed below. 544The changeable column shows whether a process with appropriate 545privilege may change the value. 546.Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent 547.It Sy "Second level name Type Changeable" 548.It "PF\_ROUTE routing messages no" 549.It "PF\_INET IPv4 values yes" 550.It "PF\_INET6 IPv6 values yes" 551.El 552.Pp 553.Bl -tag -width 6n 554.It Li PF_ROUTE 555Return the entire routing table or a subset of it. 556The data is returned as a sequence of routing messages (see 557.Xr route 4 558for the header file, format and meaning). 559The length of each message is contained in the message header. 560.Pp 561The third level name is a protocol number, which is currently always 0. 562The fourth level name is an address family, which may be set to 0 to 563select all address families. 564The fifth and sixth level names are as follows: 565.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent 566.It Sy "Fifth level name Sixth level is:" 567.It "NET\_RT\_FLAGS rtflags" 568.It "NET\_RT\_DUMP None" 569.It "NET\_RT\_IFLIST None" 570.El 571.It Li PF_INET 572Get or set various global information about the IPv4 573(Internet Protocol version 4). 574The third level name is the protocol. 575The fourth level name is the variable name. 576The currently defined protocols and names are: 577.Bl -column ProtocolXX VariableXX TypeXX ChangeableXX 578.It Sy "Protocol Variable Type Changeable" 579.It "icmp bmcastecho integer yes" 580.It "icmp maskrepl integer yes" 581.It "ip forwarding integer yes" 582.It "ip redirect integer yes" 583.It "ip ttl integer yes" 584.It "udp checksum integer yes" 585.El 586.Pp 587The variables are as follows: 588.Bl -tag -width 6n 589.It Li icmp.bmcastecho 590Returns 1 if an ICMP echo request to a broadcast or multicast address is 591to be answered. 592.It Li icmp.maskrepl 593Returns 1 if ICMP network mask requests are to be answered. 594.It Li ip.forwarding 595Returns 1 when IP forwarding is enabled for the host, 596meaning that the host is acting as a router. 597.It Li ip.redirect 598Returns 1 when ICMP redirects may be sent by the host. 599This option is ignored unless the host is routing IP packets, 600and should normally be enabled on all systems. 601.It Li ip.ttl 602The maximum time-to-live (hop count) value for an IP packet sourced by 603the system. 604This value applies to normal transport protocols, not to ICMP. 605.It Li udp.checksum 606Returns 1 when UDP checksums are being computed and checked. 607Disabling UDP checksums is strongly discouraged. 608.Pp 609For variables net.inet.*.ipsec, please refer to 610.Xr ipsec 4 . 611.El 612.It Li PF_INET6 613Get or set various global information about the IPv6 614(Internet Protocol version 6). 615The third level name is the protocol. 616The fourth level name is the variable name. 617.Pp 618For variables net.inet6.* please refer to 619.Xr inet6 4 . 620For variables net.inet6.*.ipsec6, please refer to 621.Xr ipsec 4 . 622.El 623.Ss CTL_USER 624The string and integer information available for the CTL_USER level 625is detailed below. 626The changeable column shows whether a process with appropriate 627privilege may change the value. 628.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 629.It Sy "Second level name Type Changeable" 630.It "USER\_BC\_BASE\_MAX integer no" 631.It "USER\_BC\_DIM\_MAX integer no" 632.It "USER\_BC\_SCALE\_MAX integer no" 633.It "USER\_BC\_STRING\_MAX integer no" 634.It "USER\_COLL\_WEIGHTS\_MAX integer no" 635.It "USER\_CS\_PATH string no" 636.It "USER\_EXPR\_NEST\_MAX integer no" 637.It "USER\_LINE\_MAX integer no" 638.It "USER\_POSIX2\_CHAR\_TERM integer no" 639.It "USER\_POSIX2\_C\_BIND integer no" 640.It "USER\_POSIX2\_C\_DEV integer no" 641.It "USER\_POSIX2\_FORT\_DEV integer no" 642.It "USER\_POSIX2\_FORT\_RUN integer no" 643.It "USER\_POSIX2\_LOCALEDEF integer no" 644.It "USER\_POSIX2\_SW\_DEV integer no" 645.It "USER\_POSIX2\_UPE integer no" 646.It "USER\_POSIX2\_VERSION integer no" 647.It "USER\_RE\_DUP\_MAX integer no" 648.It "USER\_STREAM\_MAX integer no" 649.It "USER\_TZNAME\_MAX integer no" 650.El 651.Bl -tag -width 6n 652.Pp 653.It Li USER_BC_BASE_MAX 654The maximum ibase/obase values in the 655.Xr bc 1 656utility. 657.It Li USER_BC_DIM_MAX 658The maximum array size in the 659.Xr bc 1 660utility. 661.It Li USER_BC_SCALE_MAX 662The maximum scale value in the 663.Xr bc 1 664utility. 665.It Li USER_BC_STRING_MAX 666The maximum string length in the 667.Xr bc 1 668utility. 669.It Li USER_COLL_WEIGHTS_MAX 670The maximum number of weights that can be assigned to any entry of 671the LC_COLLATE order keyword in the locale definition file. 672.It Li USER_CS_PATH 673Return a value for the 674.Ev PATH 675environment variable that finds all the standard utilities. 676.It Li USER_EXPR_NEST_MAX 677The maximum number of expressions that can be nested within 678parenthesis by the 679.Xr expr 1 680utility. 681.It Li USER_LINE_MAX 682The maximum length in bytes of a text-processing utility's input 683line. 684.It Li USER_POSIX2_CHAR_TERM 685Return 1 if the system supports at least one terminal type capable of 686all operations described in 687.St -p1003.2 , 688otherwise 0. 689.It Li USER_POSIX2_C_BIND 690Return 1 if the system's C-language development facilities support the 691C-Language Bindings Option, otherwise 0. 692.It Li USER_POSIX2_C_DEV 693Return 1 if the system supports the C-Language Development Utilities Option, 694otherwise 0. 695.It Li USER_POSIX2_FORT_DEV 696Return 1 if the system supports the FORTRAN Development Utilities Option, 697otherwise 0. 698.It Li USER_POSIX2_FORT_RUN 699Return 1 if the system supports the FORTRAN Runtime Utilities Option, 700otherwise 0. 701.It Li USER_POSIX2_LOCALEDEF 702Return 1 if the system supports the creation of locales, otherwise 0. 703.It Li USER_POSIX2_SW_DEV 704Return 1 if the system supports the Software Development Utilities Option, 705otherwise 0. 706.It Li USER_POSIX2_UPE 707Return 1 if the system supports the User Portability Utilities Option, 708otherwise 0. 709.It Li USER_POSIX2_VERSION 710The version of 711.St -p1003.2 712with which the system attempts to comply. 713.It Li USER_RE_DUP_MAX 714The maximum number of repeated occurrences of a regular expression 715permitted when using interval notation. 716.It Li USER_STREAM_MAX 717The minimum maximum number of streams that a process may have open 718at any one time. 719.It Li USER_TZNAME_MAX 720The minimum maximum number of types supported for the name of a 721timezone. 722.El 723.Ss CTL_VM 724The string and integer information available for the CTL_VM level 725is detailed below. 726The changeable column shows whether a process with appropriate 727privilege may change the value. 728.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 729.It Sy "Second level name Type Changeable" 730.It "VM\_LOADAVG struct loadavg no" 731.It "VM\_METER struct vmtotal no" 732.It "VM\_PAGEOUT\_ALGORITHM integer yes" 733.It "VM\_SWAPPING\_ENABLED integer maybe" 734.It "VM\_V\_CACHE\_MAX integer yes" 735.It "VM\_V\_CACHE\_MIN integer yes" 736.It "VM\_V\_FREE\_MIN integer yes" 737.It "VM\_V\_FREE\_RESERVED integer yes" 738.It "VM\_V\_FREE\_TARGET integer yes" 739.It "VM\_V\_INACTIVE\_TARGET integer yes" 740.It "VM\_V\_PAGEOUT\_FREE\_MIN integer yes" 741.El 742.Pp 743.Bl -tag -width 6n 744.It Li VM_LOADAVG 745Return the load average history. 746The returned data consists of a 747.Va struct loadavg . 748.It Li VM_METER 749Return the system wide virtual memory statistics. 750The returned data consists of a 751.Va struct vmtotal . 752.It Li VM_PAGEOUT_ALGORITHM 7530 if the statistics-based page management algorithm is in use 754or 1 if the near-LRU algorithm is in use. 755.It Li VM_SWAPPING_ENABLED 7561 if process swapping is enabled or 0 if disabled. This variable is 757permanently set to 0 if the kernel was built with swapping disabled. 758.It Li VM_V_CACHE_MAX 759Maximum desired size of the cache queue. 760.It Li VM_V_CACHE_MIN 761Minimum desired size of the cache queue. If the cache queue size 762falls very far below this value, the pageout daemon is awakened. 763.It Li VM_V_FREE_MIN 764Minimum amount of memory (cache memory plus free memory) 765required to be available before a process waiting on memory will be 766awakened. 767.It Li VM_V_FREE_RESERVED 768Processes will awaken the pageout daemon and wait for memory if the 769number of free and cached pages drops below this value. 770.It Li VM_V_FREE_TARGET 771The total amount of free memory (including cache memory) that the 772pageout daemon tries to maintain. 773.It Li VM_V_INACTIVE_TARGET 774The desired number of inactive pages that the pageout daemon should 775achieve when it runs. Inactive pages can be quickly inserted into 776process address space when needed. 777.It Li VM_V_PAGEOUT_FREE_MIN 778If the amount of free and cache memory falls below this value, the 779pageout daemon will enter "memory conserving mode" to avoid deadlock. 780.El 781.Sh RETURN VALUES 782.Rv -std 783.Sh FILES 784.Bl -tag -width ".In netinet/icmp_var.h" -compact 785.It In sys/sysctl.h 786definitions for top level identifiers, second level kernel and hardware 787identifiers, and user level identifiers 788.It In sys/socket.h 789definitions for second level network identifiers 790.It In sys/gmon.h 791definitions for third level profiling identifiers 792.It In vm/vm_param.h 793definitions for second level virtual memory identifiers 794.It In netinet/in.h 795definitions for third level IPv4/IPv6 identifiers and 796fourth level IPv4/v6 identifiers 797.It In netinet/icmp_var.h 798definitions for fourth level ICMP identifiers 799.It In netinet/icmp6.h 800definitions for fourth level ICMPv6 identifiers 801.It In netinet/udp_var.h 802definitions for fourth level UDP identifiers 803.El 804.Sh ERRORS 805The following errors may be reported: 806.Bl -tag -width Er 807.It Bq Er EFAULT 808The buffer 809.Fa name , 810.Fa oldp , 811.Fa newp , 812or length pointer 813.Fa oldlenp 814contains an invalid address. 815.It Bq Er EINVAL 816The 817.Fa name 818array is less than two or greater than CTL_MAXNAME. 819.It Bq Er EINVAL 820A non-null 821.Fa newp 822is given and its specified length in 823.Fa newlen 824is too large or too small. 825.It Bq Er ENOMEM 826The length pointed to by 827.Fa oldlenp 828is too short to hold the requested value. 829.It Bq Er ENOTDIR 830The 831.Fa name 832array specifies an intermediate rather than terminal name. 833.It Bq Er EISDIR 834The 835.Fa name 836array specifies a terminal name, but the actual name is not terminal. 837.It Bq Er ENOENT 838The 839.Fa name 840array specifies a value that is unknown. 841.It Bq Er EPERM 842An attempt is made to set a read-only value. 843.It Bq Er EPERM 844A process without appropriate privilege attempts to set a value. 845.El 846.Sh SEE ALSO 847.Xr sysconf 3 , 848.Xr sysctl 8 849.Sh HISTORY 850The 851.Fn sysctl 852function first appeared in 853.Bx 4.4 . 854