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: src/lib/libc/gen/sysctl.3,v 1.33.2.13 2002/04/07 04:57:14 dd Exp $ 30.\" $DragonFly: src/lib/libc/gen/sysctl.3,v 1.10 2008/05/02 02:05:03 swildner Exp $ 31.\" 32.Dd January 23, 2001 33.Dt SYSCTL 3 34.Os 35.Sh NAME 36.Nm sysctl , 37.Nm sysctlbyname , 38.Nm sysctlnametomib 39.Nd get or set system information 40.Sh LIBRARY 41.Lb libc 42.Sh SYNOPSIS 43.In sys/types.h 44.In sys/sysctl.h 45.Ft int 46.Fn sysctl "int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" 47.Ft int 48.Fn sysctlbyname "const char *name" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" 49.Ft int 50.Fn sysctlnametomib "const char *name" "int *mibp" "size_t *sizep" 51.Sh DESCRIPTION 52The 53.Fn sysctl 54function retrieves system information and allows processes with 55appropriate privileges to set system information. 56The information available from 57.Fn sysctl 58consists of integers, strings, and tables. 59Information may be retrieved and set from the command interface 60using the 61.Xr sysctl 8 62utility. 63.Pp 64Unless explicitly noted below, 65.Fn sysctl 66returns a consistent snapshot of the data requested. 67Consistency is obtained by locking the destination 68buffer into memory so that the data may be copied out without blocking. 69Calls to 70.Fn sysctl 71are serialized to avoid deadlock. 72.Pp 73The state is described using a ``Management Information Base'' (MIB) 74style name, listed in 75.Fa name , 76which is a 77.Fa namelen 78length array of integers. 79.Pp 80The 81.Fn sysctlbyname 82function accepts an ASCII representation of the name and internally 83looks up the integer name vector. Apart from that, it behaves the same 84as the standard 85.Fn sysctl 86function. 87.Pp 88The information is copied into the buffer specified by 89.Fa oldp . 90The size of the buffer is given by the location specified by 91.Fa oldlenp 92before the call, 93and that location gives the amount of data copied after a successful call 94and after a call that returns with the error code 95.Er ENOMEM . 96If the amount of data available is greater 97than the size of the buffer supplied, 98the call supplies as much data as fits in the buffer provided 99and returns with the error code 100.Er ENOMEM . 101If the old value is not desired, 102.Fa oldp 103and 104.Fa oldlenp 105should be set to NULL. 106.Pp 107The size of the available data can be determined by calling 108.Fn sysctl 109with a NULL parameter for 110.Fa oldp . 111The size of the available data will be returned in the location pointed to by 112.Fa oldlenp . 113For some operations, the amount of space may change often. 114For these operations, 115the system attempts to round up so that the returned size is 116large enough for a call to return the data shortly thereafter. 117.Pp 118To set a new value, 119.Fa newp 120is set to point to a buffer of length 121.Fa newlen 122from which the requested value is to be taken. 123If a new value is not to be set, 124.Fa newp 125should be set to NULL and 126.Fa newlen 127set to 0. 128.Pp 129The 130.Fn sysctlnametomib 131function accepts an ASCII representation of the name, 132looks up the integer name vector, 133and returns the numeric representation in the mib array pointed to by 134.Fa mibp . 135The number of elements in the mib array is given by the location specified by 136.Fa sizep 137before the call, 138and that location gives the number of entries copied after a successful call. 139The resulting 140.Fa mib 141and 142.Fa size 143may be used in subsequent 144.Fn sysctl 145calls to get the data associated with the requested ASCII name. 146This interface is intended for use by applications that want to 147repeatedly request the same variable (the 148.Fn sysctl 149function runs in about a third the time as the same request made via the 150.Fn sysctlbyname 151function). 152The 153.Fn sysctlnametomib 154function is also useful for fetching mib prefixes and then adding 155a final component. 156For example, to fetch process information 157for processes with pid's less than 100: 158.Pp 159.Bd -literal -offset indent -compact 160int i, mib[4]; 161size_t len; 162struct kinfo_proc kp; 163 164/* Fill out the first three components of the mib */ 165len = 4; 166sysctlnametomib("kern.proc.pid", mib, &len); 167 168/* Fetch and print entries for pid's < 100 */ 169for (i = 0; i < 100; i++) { 170 mib[3] = i; 171 len = sizeof(kp); 172 if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1) 173 perror("sysctl"); 174 else if (len > 0) 175 printkproc(&kp); 176} 177.Ed 178.Pp 179The top level names are defined with a CTL_ prefix in 180.In sys/sysctl.h , 181and are as follows. 182The next and subsequent levels down are found in the include files 183listed here, and described in separate sections below. 184.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent 185.It Sy "Name Next level names Description" 186.It "CTL\_DEBUG sys/sysctl.h Debugging" 187.It "CTL\_VFS sys/mount.h Filesystem" 188.It "CTL\_HW sys/sysctl.h Generic CPU, I/O" 189.It "CTL\_KERN sys/sysctl.h High kernel limits" 190.It "CTL\_MACHDEP sys/sysctl.h Machine dependent" 191.It "CTL\_NET sys/socket.h Networking" 192.It "CTL\_USER sys/sysctl.h User-level" 193.It "CTL\_VM vm/vm_param.h Virtual memory" 194.El 195.Pp 196For example, the following retrieves the maximum number of processes allowed 197in the system: 198.Pp 199.Bd -literal -offset indent -compact 200int mib[2], maxproc; 201size_t len; 202 203mib[0] = CTL_KERN; 204mib[1] = KERN_MAXPROC; 205len = sizeof(maxproc); 206sysctl(mib, 2, &maxproc, &len, NULL, 0); 207.Ed 208.Pp 209To retrieve the standard search path for the system utilities: 210.Pp 211.Bd -literal -offset indent -compact 212int mib[2]; 213size_t len; 214char *p; 215 216mib[0] = CTL_USER; 217mib[1] = USER_CS_PATH; 218sysctl(mib, 2, NULL, &len, NULL, 0); 219p = malloc(len); 220sysctl(mib, 2, p, &len, NULL, 0); 221.Ed 222.Ss CTL_DEBUG 223The debugging variables vary from system to system. 224A debugging variable may be added or deleted without need to recompile 225.Fn sysctl 226to know about it. 227Each time it runs, 228.Fn sysctl 229gets the list of debugging variables from the kernel and 230displays their current values. 231The system defines twenty 232.Ns ( Va struct ctldebug ) 233variables named 234.Nm debug0 235through 236.Nm debug19 . 237They are declared as separate variables so that they can be 238individually initialized at the location of their associated variable. 239The loader prevents multiple use of the same variable by issuing errors 240if a variable is initialized in more than one place. 241For example, to export the variable 242.Nm dospecialcheck 243as a debugging variable, the following declaration would be used: 244.Bd -literal -offset indent -compact 245int dospecialcheck = 1; 246struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck }; 247.Ed 248.Ss CTL_VFS 249A distinguished second level name, VFS_GENERIC, 250is used to get general information about all filesystems. 251One of its third level identifiers is VFS_MAXTYPENUM 252that gives the highest valid filesystem type number. 253Its other third level identifier is VFS_CONF that 254returns configuration information about the filesystem 255type given as a fourth level identifier (see 256.Xr getvfsbyname 3 257as an example of its use). 258The remaining second level identifiers are the 259filesystem type number returned by a 260.Xr statfs 2 261call or from VFS_CONF. 262The third level identifiers available for each filesystem 263are given in the header file that defines the mount 264argument structure for that filesystem. 265.Ss CTL_HW 266The string and integer information available for the CTL_HW level 267is detailed below. 268The changeable column shows whether a process with appropriate 269privilege may change the value. 270.Bl -column "Second level nameXXXXXX" integerXXX -offset indent 271.It Sy "Second level name Type Changeable" 272.It "HW\_MACHINE string no" 273.It "HW\_MODEL string no" 274.It "HW\_NCPU integer no" 275.It "HW\_BYTEORDER integer no" 276.It "HW\_PHYSMEM integer no" 277.It "HW\_USERMEM integer no" 278.It "HW\_PAGESIZE integer no" 279.It "HW\_FLOATINGPOINT integer no" 280.It "HW\_MACHINE\_ARCH string no" 281.\".It "HW\_DISKNAMES integer no" 282.\".It "HW\_DISKSTATS integer no" 283.It "HW_SENSORS node not applicable" 284.El 285.Bl -tag -width 6n 286.It Li HW_MACHINE 287The machine class. 288.It Li HW_MODEL 289The machine model 290.It Li HW_NCPU 291The number of cpus. 292.It Li HW_BYTEORDER 293The byteorder (4,321, or 1,234). 294.It Li HW_PHYSMEM 295The bytes of physical memory. 296.It Li HW_USERMEM 297The bytes of non-kernel memory. 298.It Li HW_PAGESIZE 299The software page size. 300.It Li HW_FLOATINGPOINT 301Nonzero if the floating point support is in hardware. 302.It Li HW_MACHINE_ARCH 303The machine dependent architecture type. 304.\".It Fa HW_DISKNAMES 305.\".It Fa HW_DISKSTATS 306.It Li HW_SENSORS 307Third level comprises an array of 308.Vt "struct sensordev" 309structures containing information about devices 310that may attach hardware monitoring sensors. 311.Pp 312Third, fourth and fifth levels together comprise an array of 313.Vt "struct sensor" 314structures containing snapshot readings of hardware monitoring sensors. 315In such usage, third level indicates the numerical representation 316of the sensor device name to which the sensor is attached 317(device's 318.Va xname 319and number shall be matched with the help of 320.Vt "struct sensordev" 321structure above), 322fourth level indicates sensor type and 323fifth level is an ordinal sensor number (unique to 324the specified sensor type on the specified sensor device). 325.Pp 326The 327.Vt sensordev 328and 329.Vt sensor 330structures 331and 332.Vt sensor_type 333enumeration 334are defined in 335.In sys/sensors.h . 336.El 337.Ss CTL_KERN 338The string and integer information available for the CTL_KERN level 339is detailed below. 340The changeable column shows whether a process with appropriate 341privilege may change the value. 342The types of data currently available are process information, 343system vnodes, the open file entries, routing table entries, 344virtual memory statistics, load average history, and clock rate 345information. 346.Bl -column "KERNXMAXPOSIXLOCKSPERUIDXXX" "struct clockrateXXX" -offset indent 347.It Sy "Second level name Type Changeable" 348.It "KERN\_ARGMAX integer no" 349.It "KERN\_BOOTFILE string yes" 350.It "KERN\_BOOTTIME struct timeval no" 351.It "KERN\_CLOCKRATE struct clockinfo no" 352.It "KERN\_FILE struct file no" 353.It "KERN\_HOSTID integer yes" 354.It "KERN\_HOSTNAME string yes" 355.It "KERN\_JOB\_CONTROL integer no" 356.It "KERN\_MAXFILES integer yes" 357.It "KERN\_MAXFILESPERPROC integer yes" 358.It "KERN\_MAXPOSIXLOCKSPERUID integer yes" 359.It "KERN\_MAXPROC integer no" 360.It "KERN\_MAXPROCPERUID integer yes" 361.It "KERN\_MAXVNODES integer yes" 362.It "KERN\_NGROUPS integer no" 363.It "KERN\_NISDOMAINNAME string yes" 364.It "KERN\_OSRELDATE integer no" 365.It "KERN\_OSRELEASE string no" 366.It "KERN\_OSREV integer no" 367.It "KERN\_OSTYPE string no" 368.It "KERN\_POSIX1 integer no" 369.It "KERN\_PROC struct proc no" 370.It "KERN\_PROF node not applicable" 371.It "KERN\_QUANTUM integer yes" 372.It "KERN\_SAVED\_IDS integer no" 373.It "KERN\_SECURELVL integer raise only" 374.It "KERN\_UPDATEINTERVAL integer no" 375.It "KERN\_VERSION string no" 376.It "KERN\_VNODE struct vnode no" 377.El 378.Bl -tag -width 6n 379.It Li KERN_ARGMAX 380The maximum bytes of argument to 381.Xr execve 2 . 382.It Li KERN_BOOTFILE 383The full pathname of the file from which the kernel was loaded. 384.It Li KERN_BOOTTIME 385A 386.Va struct timeval 387structure is returned. 388This structure contains the time that the system was booted. 389.It Li KERN_CLOCKRATE 390A 391.Va struct clockinfo 392structure is returned. 393This structure contains the clock, statistics clock and profiling clock 394frequencies, the number of micro-seconds per hz tick and the skew rate. 395.It Li KERN_FILE 396Return the entire file table. 397The returned data consists of a single 398.Va struct filehead 399followed by an array of 400.Va struct file , 401whose size depends on the current number of such objects in the system. 402.It Li KERN_HOSTID 403Get or set the host id. 404.It Li KERN_HOSTNAME 405Get or set the hostname. 406.It Li KERN_JOB_CONTROL 407Return 1 if job control is available on this system, otherwise 0. 408.It Li KERN_MAXFILES 409The maximum number of files that may be open in the system. 410.It Li KERN_MAXFILESPERPROC 411The maximum number of files that may be open for a single process. 412This limit only applies to processes with an effective uid of nonzero 413at the time of the open request. 414Files that have already been opened are not affected if the limit 415or the effective uid is changed. 416.It Li KERN_MAXPROC 417The maximum number of concurrent processes the system will allow. 418.It Li KERN_MAXPROCPERUID 419The maximum number of concurrent processes the system will allow 420for a single effective uid. 421This limit only applies to processes with an effective uid of nonzero 422at the time of a fork request. 423Processes that have already been started are not affected if the limit 424is changed. 425.It Li KERN_MAXVNODES 426The maximum number of vnodes available on the system. 427.It Li KERN_NGROUPS 428The maximum number of supplemental groups. 429.It Li KERN_NISDOMAINNAME 430The name of the current YP/NIS domain. 431.It Li KERN_OSRELDATE 432The system release date in YYYYMM format 433(January 1996 is encoded as 199601). 434.It Li KERN_OSRELEASE 435The system release string. 436.It Li KERN_OSREV 437The system revision string. 438.It Li KERN_OSTYPE 439The system type string. 440.It Li KERN_POSIX1 441The version of 442.St -p1003.1 443with which the system 444attempts to comply. 445.It Li KERN_PROC 446Return the entire process table, or a subset of it. 447An array of 448.Va struct kinfo_proc 449structures is returned, 450whose size depends on the current number of such objects in the system. 451The third and fourth level names are as follows: 452.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 453.It "Third level name Fourth level is:" 454.It "KERN\_PROC\_ALL None" 455.It "KERN\_PROC\_PID A process ID" 456.It "KERN\_PROC\_PGRP A process group" 457.It "KERN\_PROC\_TTY A tty device" 458.It "KERN\_PROC\_UID A user ID" 459.It "KERN\_PROC\_RUID A real user ID" 460.El 461.Pp 462Adding the flag 463.Li KERN_PROC_FLAG_LWP 464to the third level name signals that information about all 465light weight processes of the selected processes should be returned. 466.It Li KERN_PROF 467Return profiling information about the kernel. 468If the kernel is not compiled for profiling, 469attempts to retrieve any of the KERN_PROF values will 470fail with 471.Er ENOENT . 472The third level names for the string and integer profiling information 473is detailed below. 474The changeable column shows whether a process with appropriate 475privilege may change the value. 476.Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent 477.It Sy "Third level name Type Changeable" 478.It "GPROF\_STATE integer yes" 479.It "GPROF\_COUNT u_short[\|] yes" 480.It "GPROF\_FROMS u_short[\|] yes" 481.It "GPROF\_TOS struct tostruct yes" 482.It "GPROF\_GMONPARAM struct gmonparam no" 483.El 484.Pp 485The variables are as follows: 486.Bl -tag -width 6n 487.It Li GPROF_STATE 488Returns GMON_PROF_ON or GMON_PROF_OFF to show that profiling 489is running or stopped. 490.It Li GPROF_COUNT 491Array of statistical program counter counts. 492.It Li GPROF_FROMS 493Array indexed by program counter of call-from points. 494.It Li GPROF_TOS 495Array of 496.Va struct tostruct 497describing destination of calls and their counts. 498.It Li GPROF_GMONPARAM 499Structure giving the sizes of the above arrays. 500.El 501.It Li KERN_QUANTUM 502The maximum period of time, in microseconds, for which a process is allowed 503to run without being preempted if other processes are in the run queue. 504.It Li KERN_SAVED_IDS 505Returns 1 if saved set-group and saved set-user ID is available. 506.It Li KERN_SECURELVL 507The system security level. 508This level may be raised by processes with appropriate privilege. 509It may not be lowered. 510.It Li KERN_VERSION 511The system version string. 512.It Li KERN_VNODE 513Return the entire vnode table. 514Note, the vnode table is not necessarily a consistent snapshot of 515the system. 516The returned data consists of an array whose size depends on the 517current number of such objects in the system. 518Each element of the array contains the kernel address of a vnode 519.Va struct vnode * 520followed by the vnode itself 521.Va struct vnode . 522.El 523.Ss CTL_MACHDEP 524The set of variables defined is architecture dependent. 525The following variables are defined for the i386 architecture. 526.Bl -column "CONSOLE_DEVICEXXX" "struct bootinfoXXX" -offset indent 527.It Sy "Second level name Type Changeable" 528.It Li "CPU_CONSDEV dev_t no" 529.It Li "CPU_ADJKERNTZ int yes" 530.It Li "CPU_DISRTCSET int yes" 531.It Li "CPU_BOOTINFO struct bootinfo no" 532.It Li "CPU_WALLCLOCK int yes" 533.El 534.Ss CTL_NET 535The string and integer information available for the CTL_NET level 536is detailed below. 537The changeable column shows whether a process with appropriate 538privilege may change the value. 539.Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent 540.It Sy "Second level name Type Changeable" 541.It "PF\_ROUTE routing messages no" 542.It "PF\_INET IPv4 values yes" 543.It "PF\_INET6 IPv6 values yes" 544.El 545.Bl -tag -width 6n 546.It Li PF_ROUTE 547Return the entire routing table or a subset of it. 548The data is returned as a sequence of routing messages (see 549.Xr route 4 550for the header file, format and meaning). 551The length of each message is contained in the message header. 552.Pp 553The third level name is a protocol number, which is currently always 0. 554The fourth level name is an address family, which may be set to 0 to 555select all address families. 556The fifth and sixth level names are as follows: 557.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent 558.It Sy "Fifth level name Sixth level is:" 559.It "NET\_RT\_FLAGS rtflags" 560.It "NET\_RT\_DUMP None" 561.It "NET\_RT\_IFLIST None" 562.El 563.It Li PF_INET 564Get or set various global information about the IPv4 565(Internet Protocol version 4). 566The third level name is the protocol. 567The fourth level name is the variable name. 568The currently defined protocols and names are: 569.Bl -column ProtocolXX VariableXX TypeXX ChangeableXX 570.It Sy "Protocol Variable Type Changeable" 571.It "icmp bmcastecho integer yes" 572.It "icmp maskrepl integer yes" 573.It "ip forwarding integer yes" 574.It "ip redirect integer yes" 575.It "ip ttl integer yes" 576.It "udp checksum integer yes" 577.El 578.Pp 579The variables are as follows: 580.Bl -tag -width 6n 581.It Li icmp.bmcastecho 582Returns 1 if an ICMP echo request to a broadcast or multicast address is 583to be answered. 584.It Li icmp.maskrepl 585Returns 1 if ICMP network mask requests are to be answered. 586.It Li ip.forwarding 587Returns 1 when IP forwarding is enabled for the host, 588meaning that the host is acting as a router. 589.It Li ip.redirect 590Returns 1 when ICMP redirects may be sent by the host. 591This option is ignored unless the host is routing IP packets, 592and should normally be enabled on all systems. 593.It Li ip.ttl 594The maximum time-to-live (hop count) value for an IP packet sourced by 595the system. 596This value applies to normal transport protocols, not to ICMP. 597.It Li udp.checksum 598Returns 1 when UDP checksums are being computed and checked. 599Disabling UDP checksums is strongly discouraged. 600.Pp 601For variables net.inet.*.ipsec, please refer to 602.Xr ipsec 4 . 603.El 604.It Li PF_INET6 605Get or set various global information about the IPv6 606(Internet Protocol version 6). 607The third level name is the protocol. 608The fourth level name is the variable name. 609.Pp 610For variables net.inet6.* please refer to 611.Xr inet6 4 . 612For variables net.inet6.*.ipsec6, please refer to 613.Xr ipsec 4 . 614.El 615.Ss CTL_USER 616The string and integer information available for the CTL_USER level 617is detailed below. 618The changeable column shows whether a process with appropriate 619privilege may change the value. 620.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 621.It Sy "Second level name Type Changeable" 622.It "USER\_BC\_BASE\_MAX integer no" 623.It "USER\_BC\_DIM\_MAX integer no" 624.It "USER\_BC\_SCALE\_MAX integer no" 625.It "USER\_BC\_STRING\_MAX integer no" 626.It "USER\_COLL\_WEIGHTS\_MAX integer no" 627.It "USER\_CS\_PATH string no" 628.It "USER\_EXPR\_NEST\_MAX integer no" 629.It "USER\_LINE\_MAX integer no" 630.It "USER\_POSIX2\_CHAR\_TERM integer no" 631.It "USER\_POSIX2\_C\_BIND integer no" 632.It "USER\_POSIX2\_C\_DEV integer no" 633.It "USER\_POSIX2\_FORT\_DEV integer no" 634.It "USER\_POSIX2\_FORT\_RUN integer no" 635.It "USER\_POSIX2\_LOCALEDEF integer no" 636.It "USER\_POSIX2\_SW\_DEV integer no" 637.It "USER\_POSIX2\_UPE integer no" 638.It "USER\_POSIX2\_VERSION integer no" 639.It "USER\_RE\_DUP\_MAX integer no" 640.It "USER\_STREAM\_MAX integer no" 641.It "USER\_TZNAME\_MAX integer no" 642.El 643.Bl -tag -width 6n 644.It Li USER_BC_BASE_MAX 645The maximum ibase/obase values in the 646.Xr bc 1 647utility. 648.It Li USER_BC_DIM_MAX 649The maximum array size in the 650.Xr bc 1 651utility. 652.It Li USER_BC_SCALE_MAX 653The maximum scale value in the 654.Xr bc 1 655utility. 656.It Li USER_BC_STRING_MAX 657The maximum string length in the 658.Xr bc 1 659utility. 660.It Li USER_COLL_WEIGHTS_MAX 661The maximum number of weights that can be assigned to any entry of 662the LC_COLLATE order keyword in the locale definition file. 663.It Li USER_CS_PATH 664Return a value for the 665.Ev PATH 666environment variable that finds all the standard utilities. 667.It Li USER_EXPR_NEST_MAX 668The maximum number of expressions that can be nested within 669parenthesis by the 670.Xr expr 1 671utility. 672.It Li USER_LINE_MAX 673The maximum length in bytes of a text-processing utility's input 674line. 675.It Li USER_POSIX2_CHAR_TERM 676Return 1 if the system supports at least one terminal type capable of 677all operations described in 678.St -p1003.2 , 679otherwise 0. 680.It Li USER_POSIX2_C_BIND 681Return 1 if the system's C-language development facilities support the 682C-Language Bindings Option, otherwise 0. 683.It Li USER_POSIX2_C_DEV 684Return 1 if the system supports the C-Language Development Utilities Option, 685otherwise 0. 686.It Li USER_POSIX2_FORT_DEV 687Return 1 if the system supports the FORTRAN Development Utilities Option, 688otherwise 0. 689.It Li USER_POSIX2_FORT_RUN 690Return 1 if the system supports the FORTRAN Runtime Utilities Option, 691otherwise 0. 692.It Li USER_POSIX2_LOCALEDEF 693Return 1 if the system supports the creation of locales, otherwise 0. 694.It Li USER_POSIX2_SW_DEV 695Return 1 if the system supports the Software Development Utilities Option, 696otherwise 0. 697.It Li USER_POSIX2_UPE 698Return 1 if the system supports the User Portability Utilities Option, 699otherwise 0. 700.It Li USER_POSIX2_VERSION 701The version of 702.St -p1003.2 703with which the system attempts to comply. 704.It Li USER_RE_DUP_MAX 705The maximum number of repeated occurrences of a regular expression 706permitted when using interval notation. 707.It Li USER_STREAM_MAX 708The minimum maximum number of streams that a process may have open 709at any one time. 710.It Li USER_TZNAME_MAX 711The minimum maximum number of types supported for the name of a 712timezone. 713.El 714.Ss CTL_VM 715The string and integer information available for the CTL_VM level 716is detailed below. 717The changeable column shows whether a process with appropriate 718privilege may change the value. 719.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 720.It Sy "Second level name Type Changeable" 721.It "VM\_LOADAVG struct loadavg no" 722.It "VM\_METER struct vmtotal no" 723.It "VM\_PAGEOUT\_ALGORITHM integer yes" 724.It "VM\_SWAPPING\_ENABLED integer maybe" 725.It "VM\_V\_CACHE\_MAX integer yes" 726.It "VM\_V\_CACHE\_MIN integer yes" 727.It "VM\_V\_FREE\_MIN integer yes" 728.It "VM\_V\_FREE\_RESERVED integer yes" 729.It "VM\_V\_FREE\_TARGET integer yes" 730.It "VM\_V\_INACTIVE\_TARGET integer yes" 731.It "VM\_V\_PAGEOUT\_FREE\_MIN integer yes" 732.El 733.Bl -tag -width 6n 734.It Li VM_LOADAVG 735Return the load average history. 736The returned data consists of a 737.Va struct loadavg . 738.It Li VM_METER 739Return the system wide virtual memory statistics. 740The returned data consists of a 741.Va struct vmtotal . 742.It Li VM_PAGEOUT_ALGORITHM 7430 if the statistics-based page management algorithm is in use 744or 1 if the near-LRU algorithm is in use. 745.It Li VM_SWAPPING_ENABLED 7461 if process swapping is enabled or 0 if disabled. This variable is 747permanently set to 0 if the kernel was built with swapping disabled. 748.It Li VM_V_CACHE_MAX 749Maximum desired size of the cache queue. 750.It Li VM_V_CACHE_MIN 751Minimum desired size of the cache queue. If the cache queue size 752falls very far below this value, the pageout daemon is awakened. 753.It Li VM_V_FREE_MIN 754Minimum amount of memory (cache memory plus free memory) 755required to be available before a process waiting on memory will be 756awakened. 757.It Li VM_V_FREE_RESERVED 758Processes will awaken the pageout daemon and wait for memory if the 759number of free and cached pages drops below this value. 760.It Li VM_V_FREE_TARGET 761The total amount of free memory (including cache memory) that the 762pageout daemon tries to maintain. 763.It Li VM_V_INACTIVE_TARGET 764The desired number of inactive pages that the pageout daemon should 765achieve when it runs. Inactive pages can be quickly inserted into 766process address space when needed. 767.It Li VM_V_PAGEOUT_FREE_MIN 768If the amount of free and cache memory falls below this value, the 769pageout daemon will enter "memory conserving mode" to avoid deadlock. 770.El 771.Sh RETURN VALUES 772.Rv -std 773.Sh FILES 774.Bl -tag -width ".In netinet/icmp_var.h" -compact 775.It In sys/sysctl.h 776definitions for top level identifiers, second level kernel and hardware 777identifiers, and user level identifiers 778.It In sys/socket.h 779definitions for second level network identifiers 780.It In sys/gmon.h 781definitions for third level profiling identifiers 782.It In vm/vm_param.h 783definitions for second level virtual memory identifiers 784.It In netinet/in.h 785definitions for third level IPv4/IPv6 identifiers and 786fourth level IPv4/v6 identifiers 787.It In netinet/icmp_var.h 788definitions for fourth level ICMP identifiers 789.It In netinet/icmp6.h 790definitions for fourth level ICMPv6 identifiers 791.It In netinet/udp_var.h 792definitions for fourth level UDP identifiers 793.El 794.Sh ERRORS 795The following errors may be reported: 796.Bl -tag -width Er 797.It Bq Er EFAULT 798The buffer 799.Fa name , 800.Fa oldp , 801.Fa newp , 802or length pointer 803.Fa oldlenp 804contains an invalid address. 805.It Bq Er EINVAL 806The 807.Fa name 808array is less than two or greater than CTL_MAXNAME. 809.It Bq Er EINVAL 810A non-null 811.Fa newp 812is given and its specified length in 813.Fa newlen 814is too large or too small. 815.It Bq Er ENOMEM 816The length pointed to by 817.Fa oldlenp 818is too short to hold the requested value. 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 sysconf 3 , 838.Xr sysctl 8 839.Sh HISTORY 840The 841.Fn sysctl 842function first appeared in 843.Bx 4.4 . 844