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 1.10 2008/05/02 02:05:03 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.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent 189.It Sy "Name Next level names Description" 190.It "CTL\_DEBUG sys/sysctl.h Debugging" 191.It "CTL\_VFS sys/mount.h Filesystem" 192.It "CTL\_HW sys/sysctl.h Generic CPU, I/O" 193.It "CTL\_KERN sys/sysctl.h High kernel limits" 194.It "CTL\_MACHDEP sys/sysctl.h Machine dependent" 195.It "CTL\_NET sys/socket.h Networking" 196.It "CTL\_USER sys/sysctl.h User-level" 197.It "CTL\_VM vm/vm_param.h Virtual memory" 198.El 199.Pp 200For example, the following retrieves the maximum number of processes allowed 201in the system: 202.Pp 203.Bd -literal -offset indent -compact 204int mib[2], maxproc; 205size_t len; 206 207mib[0] = CTL_KERN; 208mib[1] = KERN_MAXPROC; 209len = sizeof(maxproc); 210sysctl(mib, 2, &maxproc, &len, NULL, 0); 211.Ed 212.Pp 213To retrieve the standard search path for the system utilities: 214.Pp 215.Bd -literal -offset indent -compact 216int mib[2]; 217size_t len; 218char *p; 219 220mib[0] = CTL_USER; 221mib[1] = USER_CS_PATH; 222sysctl(mib, 2, NULL, &len, NULL, 0); 223p = malloc(len); 224sysctl(mib, 2, p, &len, NULL, 0); 225.Ed 226.Ss CTL_DEBUG 227The debugging variables vary from system to system. 228A debugging variable may be added or deleted without need to recompile 229.Fn sysctl 230to know about it. 231Each time it runs, 232.Fn sysctl 233gets the list of debugging variables from the kernel and 234displays their current values. 235The system defines twenty 236.Ns ( Va struct ctldebug ) 237variables named 238.Nm debug0 239through 240.Nm debug19 . 241They are declared as separate variables so that they can be 242individually initialized at the location of their associated variable. 243The loader prevents multiple use of the same variable by issuing errors 244if a variable is initialized in more than one place. 245For example, to export the variable 246.Nm dospecialcheck 247as a debugging variable, the following declaration would be used: 248.Bd -literal -offset indent -compact 249int dospecialcheck = 1; 250struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck }; 251.Ed 252.Ss CTL_VFS 253A distinguished second level name, VFS_GENERIC, 254is used to get general information about all filesystems. 255One of its third level identifiers is VFS_MAXTYPENUM 256that gives the highest valid filesystem type number. 257Its other third level identifier is VFS_CONF that 258returns configuration information about the filesystem 259type given as a fourth level identifier (see 260.Xr getvfsbyname 3 261as an example of its use). 262The remaining second level identifiers are the 263filesystem type number returned by a 264.Xr statfs 2 265call or from VFS_CONF. 266The third level identifiers available for each filesystem 267are given in the header file that defines the mount 268argument structure for that filesystem. 269.Ss CTL_HW 270The string and integer information available for the CTL_HW level 271is detailed below. 272The changeable column shows whether a process with appropriate 273privilege may change the value. 274.Bl -column "Second level nameXXXXXX" integerXXX -offset indent 275.It Sy "Second level name Type Changeable" 276.It "HW\_MACHINE string no" 277.It "HW\_MODEL string no" 278.It "HW\_NCPU integer no" 279.It "HW\_BYTEORDER integer no" 280.It "HW\_PHYSMEM integer no" 281.It "HW\_USERMEM integer no" 282.It "HW\_PAGESIZE integer no" 283.It "HW\_FLOATINGPOINT integer no" 284.It "HW\_MACHINE\_ARCH string no" 285.\".It "HW\_DISKNAMES integer no" 286.\".It "HW\_DISKSTATS integer no" 287.It "HW_SENSORS node not applicable" 288.El 289.Bl -tag -width 6n 290.It Li HW_MACHINE 291The machine class. 292.It Li HW_MODEL 293The machine model 294.It Li HW_NCPU 295The number of cpus. 296.It Li HW_BYTEORDER 297The byteorder (4,321, or 1,234). 298.It Li HW_PHYSMEM 299The bytes of physical memory. 300.It Li HW_USERMEM 301The bytes of non-kernel memory. 302.It Li HW_PAGESIZE 303The software page size. 304.It Li HW_FLOATINGPOINT 305Nonzero if the floating point support is in hardware. 306.It Li HW_MACHINE_ARCH 307The machine dependent architecture type. 308.\".It Fa HW_DISKNAMES 309.\".It Fa HW_DISKSTATS 310.It Li HW_SENSORS 311Third level comprises an array of 312.Vt "struct sensordev" 313structures containing information about devices 314that may attach hardware monitoring sensors. 315.Pp 316Third, fourth and fifth levels together comprise an array of 317.Vt "struct sensor" 318structures containing snapshot readings of hardware monitoring sensors. 319In such usage, third level indicates the numerical representation 320of the sensor device name to which the sensor is attached 321(device's 322.Va xname 323and number shall be matched with the help of 324.Vt "struct sensordev" 325structure above), 326fourth level indicates sensor type and 327fifth level is an ordinal sensor number (unique to 328the specified sensor type on the specified sensor device). 329.Pp 330The 331.Vt sensordev 332and 333.Vt sensor 334structures 335and 336.Vt sensor_type 337enumeration 338are defined in 339.In sys/sensors.h . 340.El 341.Ss CTL_KERN 342The string and integer information available for the CTL_KERN level 343is detailed below. 344The changeable column shows whether a process with appropriate 345privilege may change the value. 346The types of data currently available are process information, 347system vnodes, the open file entries, routing table entries, 348virtual memory statistics, load average history, and clock rate 349information. 350.Bl -column "KERNXMAXPOSIXLOCKSPERUIDXXX" "struct clockrateXXX" -offset indent 351.It Sy "Second level name Type Changeable" 352.It "KERN\_ARGMAX integer no" 353.It "KERN\_BOOTFILE string yes" 354.It "KERN\_BOOTTIME struct timeval no" 355.It "KERN\_CLOCKRATE struct clockinfo no" 356.It "KERN\_FILE struct file no" 357.It "KERN\_HOSTID integer yes" 358.It "KERN\_HOSTNAME string yes" 359.It "KERN\_JOB\_CONTROL integer no" 360.It "KERN\_MAXFILES integer yes" 361.It "KERN\_MAXFILESPERPROC integer yes" 362.It "KERN\_MAXPOSIXLOCKSPERUID integer yes" 363.It "KERN\_MAXPROC integer no" 364.It "KERN\_MAXPROCPERUID integer yes" 365.It "KERN\_MAXVNODES integer yes" 366.It "KERN\_NGROUPS integer no" 367.It "KERN\_NISDOMAINNAME string yes" 368.It "KERN\_OSRELDATE integer no" 369.It "KERN\_OSRELEASE string no" 370.It "KERN\_OSREV integer no" 371.It "KERN\_OSTYPE string no" 372.It "KERN\_POSIX1 integer no" 373.It "KERN\_PROC struct proc no" 374.It "KERN\_PROF node not applicable" 375.It "KERN\_QUANTUM integer yes" 376.It "KERN\_SAVED\_IDS integer no" 377.It "KERN\_SECURELVL integer raise only" 378.It "KERN\_UPDATEINTERVAL integer no" 379.It "KERN\_VERSION string no" 380.It "KERN\_VNODE struct vnode no" 381.El 382.Bl -tag -width 6n 383.It Li KERN_ARGMAX 384The maximum bytes of argument to 385.Xr execve 2 . 386.It Li KERN_BOOTFILE 387The full pathname of the file from which the kernel was loaded. 388.It Li KERN_BOOTTIME 389A 390.Va struct timeval 391structure is returned. 392This structure contains the time that the system was booted. 393.It Li KERN_CLOCKRATE 394A 395.Va struct clockinfo 396structure is returned. 397This structure contains the clock, statistics clock and profiling clock 398frequencies, the number of micro-seconds per hz tick and the skew rate. 399.It Li KERN_FILE 400Return the entire file table. 401The returned data consists of a single 402.Va struct filehead 403followed by an array of 404.Va struct file , 405whose size depends on the current number of such objects in the system. 406.It Li KERN_HOSTID 407Get or set the host id. 408.It Li KERN_HOSTNAME 409Get or set the hostname. 410.It Li KERN_JOB_CONTROL 411Return 1 if job control is available on this system, otherwise 0. 412.It Li KERN_MAXFILES 413The maximum number of files that may be open in the system. 414.It Li KERN_MAXFILESPERPROC 415The maximum number of files that may be open for a single process. 416This limit only applies to processes with an effective uid of nonzero 417at the time of the open request. 418Files that have already been opened are not affected if the limit 419or the effective uid is changed. 420.It Li KERN_MAXPROC 421The maximum number of concurrent processes the system will allow. 422.It Li KERN_MAXPROCPERUID 423The maximum number of concurrent processes the system will allow 424for a single effective uid. 425This limit only applies to processes with an effective uid of nonzero 426at the time of a fork request. 427Processes that have already been started are not affected if the limit 428is changed. 429.It Li KERN_MAXVNODES 430The maximum number of vnodes available on the system. 431.It Li KERN_NGROUPS 432The maximum number of supplemental groups. 433.It Li KERN_NISDOMAINNAME 434The name of the current YP/NIS domain. 435.It Li KERN_OSRELDATE 436The system release date in YYYYMM format 437(January 1996 is encoded as 199601). 438.It Li KERN_OSRELEASE 439The system release string. 440.It Li KERN_OSREV 441The system revision string. 442.It Li KERN_OSTYPE 443The system type string. 444.It Li KERN_POSIX1 445The version of 446.St -p1003.1 447with which the system 448attempts to comply. 449.It Li KERN_PROC 450Return the entire process table, or a subset of it. 451An array of 452.Va struct kinfo_proc 453structures is returned, 454whose size depends on the current number of such objects in the system. 455The third and fourth level names are as follows: 456.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 457.It "Third level name Fourth level is:" 458.It "KERN\_PROC\_ALL None" 459.It "KERN\_PROC\_PID A process ID" 460.It "KERN\_PROC\_PGRP A process group" 461.It "KERN\_PROC\_TTY A tty device" 462.It "KERN\_PROC\_UID A user ID" 463.It "KERN\_PROC\_RUID A real user ID" 464.El 465.Pp 466Adding the flag 467.Li KERN_PROC_FLAG_LWP 468to the third level name signals that information about all 469light weight processes of the selected processes should be returned. 470.It Li KERN_PROF 471Return profiling information about the kernel. 472If the kernel is not compiled for profiling, 473attempts to retrieve any of the KERN_PROF values will 474fail with 475.Er ENOENT . 476The third level names for the string and integer profiling information 477is detailed below. 478The changeable column shows whether a process with appropriate 479privilege may change the value. 480.Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent 481.It Sy "Third level name Type Changeable" 482.It "GPROF\_STATE integer yes" 483.It "GPROF\_COUNT u_short[\|] yes" 484.It "GPROF\_FROMS u_short[\|] yes" 485.It "GPROF\_TOS struct tostruct yes" 486.It "GPROF\_GMONPARAM struct gmonparam no" 487.El 488.Pp 489The variables are as follows: 490.Bl -tag -width 6n 491.It Li GPROF_STATE 492Returns GMON_PROF_ON or GMON_PROF_OFF to show that profiling 493is running or stopped. 494.It Li GPROF_COUNT 495Array of statistical program counter counts. 496.It Li GPROF_FROMS 497Array indexed by program counter of call-from points. 498.It Li GPROF_TOS 499Array of 500.Va struct tostruct 501describing destination of calls and their counts. 502.It Li GPROF_GMONPARAM 503Structure giving the sizes of the above arrays. 504.El 505.It Li KERN_QUANTUM 506The maximum period of time, in microseconds, for which a process is allowed 507to run without being preempted if other processes are in the run queue. 508.It Li KERN_SAVED_IDS 509Returns 1 if saved set-group and saved set-user ID is available. 510.It Li KERN_SECURELVL 511The system security level. 512This level may be raised by processes with appropriate privilege. 513It may not be lowered. 514.It Li KERN_VERSION 515The system version string. 516.It Li KERN_VNODE 517Return the entire vnode table. 518Note, the vnode table is not necessarily a consistent snapshot of 519the system. 520The returned data consists of an array whose size depends on the 521current number of such objects in the system. 522Each element of the array contains the kernel address of a vnode 523.Va struct vnode * 524followed by the vnode itself 525.Va struct vnode . 526.El 527.Ss CTL_MACHDEP 528The set of variables defined is architecture dependent. 529The following variables are defined for the i386 architecture. 530.Bl -column "CONSOLE_DEVICEXXX" "struct bootinfoXXX" -offset indent 531.It Sy "Second level name Type Changeable" 532.It Li "CPU_CONSDEV dev_t no" 533.It Li "CPU_ADJKERNTZ int yes" 534.It Li "CPU_DISRTCSET int yes" 535.It Li "CPU_BOOTINFO struct bootinfo no" 536.It Li "CPU_WALLCLOCK int yes" 537.El 538.Ss 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 "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.Bl -tag -width 6n 550.It Li PF_ROUTE 551Return the entire routing table or a subset of it. 552The data is returned as a sequence of routing messages (see 553.Xr route 4 554for the header file, format and meaning). 555The length of each message is contained in the message header. 556.Pp 557The third level name is a protocol number, which is currently always 0. 558The fourth level name is an address family, which may be set to 0 to 559select all address families. 560The fifth and sixth level names are as follows: 561.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent 562.It Sy "Fifth level name Sixth level is:" 563.It "NET\_RT\_FLAGS rtflags" 564.It "NET\_RT\_DUMP None" 565.It "NET\_RT\_IFLIST None" 566.El 567.It Li PF_INET 568Get or set various global information about the IPv4 569(Internet Protocol version 4). 570The third level name is the protocol. 571The fourth level name is the variable name. 572The currently defined protocols and names are: 573.Bl -column ProtocolXX VariableXX TypeXX ChangeableXX 574.It Sy "Protocol Variable Type Changeable" 575.It "icmp bmcastecho integer yes" 576.It "icmp maskrepl integer yes" 577.It "ip forwarding integer yes" 578.It "ip redirect integer yes" 579.It "ip ttl integer yes" 580.It "udp checksum integer yes" 581.El 582.Pp 583The variables are as follows: 584.Bl -tag -width 6n 585.It Li icmp.bmcastecho 586Returns 1 if an ICMP echo request to a broadcast or multicast address is 587to be answered. 588.It Li icmp.maskrepl 589Returns 1 if ICMP network mask requests are to be answered. 590.It Li ip.forwarding 591Returns 1 when IP forwarding is enabled for the host, 592meaning that the host is acting as a router. 593.It Li ip.redirect 594Returns 1 when ICMP redirects may be sent by the host. 595This option is ignored unless the host is routing IP packets, 596and should normally be enabled on all systems. 597.It Li ip.ttl 598The maximum time-to-live (hop count) value for an IP packet sourced by 599the system. 600This value applies to normal transport protocols, not to ICMP. 601.It Li udp.checksum 602Returns 1 when UDP checksums are being computed and checked. 603Disabling UDP checksums is strongly discouraged. 604.Pp 605For variables net.inet.*.ipsec, please refer to 606.Xr ipsec 4 . 607.El 608.It Li PF_INET6 609Get or set various global information about the IPv6 610(Internet Protocol version 6). 611The third level name is the protocol. 612The fourth level name is the variable name. 613.Pp 614For variables net.inet6.* please refer to 615.Xr inet6 4 . 616For variables net.inet6.*.ipsec6, please refer to 617.Xr ipsec 4 . 618.El 619.Ss CTL_USER 620The string and integer information available for the CTL_USER level 621is detailed below. 622The changeable column shows whether a process with appropriate 623privilege may change the value. 624.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 625.It Sy "Second level name Type Changeable" 626.It "USER\_BC\_BASE\_MAX integer no" 627.It "USER\_BC\_DIM\_MAX integer no" 628.It "USER\_BC\_SCALE\_MAX integer no" 629.It "USER\_BC\_STRING\_MAX integer no" 630.It "USER\_COLL\_WEIGHTS\_MAX integer no" 631.It "USER\_CS\_PATH string no" 632.It "USER\_EXPR\_NEST\_MAX integer no" 633.It "USER\_LINE\_MAX integer no" 634.It "USER\_POSIX2\_CHAR\_TERM integer no" 635.It "USER\_POSIX2\_C\_BIND integer no" 636.It "USER\_POSIX2\_C\_DEV integer no" 637.It "USER\_POSIX2\_FORT\_DEV integer no" 638.It "USER\_POSIX2\_FORT\_RUN integer no" 639.It "USER\_POSIX2\_LOCALEDEF integer no" 640.It "USER\_POSIX2\_SW\_DEV integer no" 641.It "USER\_POSIX2\_UPE integer no" 642.It "USER\_POSIX2\_VERSION integer no" 643.It "USER\_RE\_DUP\_MAX integer no" 644.It "USER\_STREAM\_MAX integer no" 645.It "USER\_TZNAME\_MAX integer no" 646.El 647.Bl -tag -width 6n 648.It Li USER_BC_BASE_MAX 649The maximum ibase/obase values in the 650.Xr bc 1 651utility. 652.It Li USER_BC_DIM_MAX 653The maximum array size in the 654.Xr bc 1 655utility. 656.It Li USER_BC_SCALE_MAX 657The maximum scale value in the 658.Xr bc 1 659utility. 660.It Li USER_BC_STRING_MAX 661The maximum string length in the 662.Xr bc 1 663utility. 664.It Li USER_COLL_WEIGHTS_MAX 665The maximum number of weights that can be assigned to any entry of 666the LC_COLLATE order keyword in the locale definition file. 667.It Li USER_CS_PATH 668Return a value for the 669.Ev PATH 670environment variable that finds all the standard utilities. 671.It Li USER_EXPR_NEST_MAX 672The maximum number of expressions that can be nested within 673parenthesis by the 674.Xr expr 1 675utility. 676.It Li USER_LINE_MAX 677The maximum length in bytes of a text-processing utility's input 678line. 679.It Li USER_POSIX2_CHAR_TERM 680Return 1 if the system supports at least one terminal type capable of 681all operations described in 682.St -p1003.2 , 683otherwise 0. 684.It Li USER_POSIX2_C_BIND 685Return 1 if the system's C-language development facilities support the 686C-Language Bindings Option, otherwise 0. 687.It Li USER_POSIX2_C_DEV 688Return 1 if the system supports the C-Language Development Utilities Option, 689otherwise 0. 690.It Li USER_POSIX2_FORT_DEV 691Return 1 if the system supports the FORTRAN Development Utilities Option, 692otherwise 0. 693.It Li USER_POSIX2_FORT_RUN 694Return 1 if the system supports the FORTRAN Runtime Utilities Option, 695otherwise 0. 696.It Li USER_POSIX2_LOCALEDEF 697Return 1 if the system supports the creation of locales, otherwise 0. 698.It Li USER_POSIX2_SW_DEV 699Return 1 if the system supports the Software Development Utilities Option, 700otherwise 0. 701.It Li USER_POSIX2_UPE 702Return 1 if the system supports the User Portability Utilities Option, 703otherwise 0. 704.It Li USER_POSIX2_VERSION 705The version of 706.St -p1003.2 707with which the system attempts to comply. 708.It Li USER_RE_DUP_MAX 709The maximum number of repeated occurrences of a regular expression 710permitted when using interval notation. 711.It Li USER_STREAM_MAX 712The minimum maximum number of streams that a process may have open 713at any one time. 714.It Li USER_TZNAME_MAX 715The minimum maximum number of types supported for the name of a 716timezone. 717.El 718.Ss CTL_VM 719The string and integer information available for the CTL_VM level 720is detailed below. 721The changeable column shows whether a process with appropriate 722privilege may change the value. 723.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 724.It Sy "Second level name Type Changeable" 725.It "VM\_LOADAVG struct loadavg no" 726.It "VM\_METER struct vmtotal no" 727.It "VM\_PAGEOUT\_ALGORITHM integer yes" 728.It "VM\_SWAPPING\_ENABLED integer maybe" 729.It "VM\_V\_CACHE\_MAX integer yes" 730.It "VM\_V\_CACHE\_MIN integer yes" 731.It "VM\_V\_FREE\_MIN integer yes" 732.It "VM\_V\_FREE\_RESERVED integer yes" 733.It "VM\_V\_FREE\_TARGET integer yes" 734.It "VM\_V\_INACTIVE\_TARGET integer yes" 735.It "VM\_V\_PAGEOUT\_FREE\_MIN integer yes" 736.El 737.Bl -tag -width 6n 738.It Li VM_LOADAVG 739Return the load average history. 740The returned data consists of a 741.Va struct loadavg . 742.It Li VM_METER 743Return the system wide virtual memory statistics. 744The returned data consists of a 745.Va struct vmtotal . 746.It Li VM_PAGEOUT_ALGORITHM 7470 if the statistics-based page management algorithm is in use 748or 1 if the near-LRU algorithm is in use. 749.It Li VM_SWAPPING_ENABLED 7501 if process swapping is enabled or 0 if disabled. This variable is 751permanently set to 0 if the kernel was built with swapping disabled. 752.It Li VM_V_CACHE_MAX 753Maximum desired size of the cache queue. 754.It Li VM_V_CACHE_MIN 755Minimum desired size of the cache queue. If the cache queue size 756falls very far below this value, the pageout daemon is awakened. 757.It Li VM_V_FREE_MIN 758Minimum amount of memory (cache memory plus free memory) 759required to be available before a process waiting on memory will be 760awakened. 761.It Li VM_V_FREE_RESERVED 762Processes will awaken the pageout daemon and wait for memory if the 763number of free and cached pages drops below this value. 764.It Li VM_V_FREE_TARGET 765The total amount of free memory (including cache memory) that the 766pageout daemon tries to maintain. 767.It Li VM_V_INACTIVE_TARGET 768The desired number of inactive pages that the pageout daemon should 769achieve when it runs. Inactive pages can be quickly inserted into 770process address space when needed. 771.It Li VM_V_PAGEOUT_FREE_MIN 772If the amount of free and cache memory falls below this value, the 773pageout daemon will enter "memory conserving mode" to avoid deadlock. 774.El 775.Sh RETURN VALUES 776.Rv -std 777.Sh FILES 778.Bl -tag -width ".In netinet/icmp_var.h" -compact 779.It In sys/sysctl.h 780definitions for top level identifiers, second level kernel and hardware 781identifiers, and user level identifiers 782.It In sys/socket.h 783definitions for second level network identifiers 784.It In sys/gmon.h 785definitions for third level profiling identifiers 786.It In vm/vm_param.h 787definitions for second level virtual memory identifiers 788.It In netinet/in.h 789definitions for third level IPv4/IPv6 identifiers and 790fourth level IPv4/v6 identifiers 791.It In netinet/icmp_var.h 792definitions for fourth level ICMP identifiers 793.It In netinet/icmp6.h 794definitions for fourth level ICMPv6 identifiers 795.It In netinet/udp_var.h 796definitions for fourth level UDP identifiers 797.El 798.Sh ERRORS 799The following errors may be reported: 800.Bl -tag -width Er 801.It Bq Er EFAULT 802The buffer 803.Fa name , 804.Fa oldp , 805.Fa newp , 806or length pointer 807.Fa oldlenp 808contains an invalid address. 809.It Bq Er EINVAL 810The 811.Fa name 812array is less than two or greater than CTL_MAXNAME. 813.It Bq Er EINVAL 814A non-null 815.Fa newp 816is given and its specified length in 817.Fa newlen 818is too large or too small. 819.It Bq Er ENOMEM 820The length pointed to by 821.Fa oldlenp 822is too short to hold the requested value. 823.It Bq Er ENOTDIR 824The 825.Fa name 826array specifies an intermediate rather than terminal name. 827.It Bq Er EISDIR 828The 829.Fa name 830array specifies a terminal name, but the actual name is not terminal. 831.It Bq Er ENOENT 832The 833.Fa name 834array specifies a value that is unknown. 835.It Bq Er EPERM 836An attempt is made to set a read-only value. 837.It Bq Er EPERM 838A process without appropriate privilege attempts to set a value. 839.El 840.Sh SEE ALSO 841.Xr sysconf 3 , 842.Xr sysctl 8 843.Sh HISTORY 844The 845.Fn sysctl 846function first appeared in 847.Bx 4.4 . 848