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 1.6 2007/02/01 10:33:26 corecode 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.El 289.Pp 290.Bl -tag -width 6n 291.It Li HW_MACHINE 292The machine class. 293.It Li HW_MODEL 294The machine model 295.It Li HW_NCPU 296The number of cpus. 297.It Li HW_BYTEORDER 298The byteorder (4,321, or 1,234). 299.It Li HW_PHYSMEM 300The bytes of physical memory. 301.It Li HW_USERMEM 302The bytes of non-kernel memory. 303.It Li HW_PAGESIZE 304The software page size. 305.It Li HW_FLOATINGPOINT 306Nonzero if the floating point support is in hardware. 307.It Li HW_MACHINE_ARCH 308The machine dependent architecture type. 309.\".It Fa HW_DISKNAMES 310.\".It Fa HW_DISKSTATS 311.El 312.Ss CTL_KERN 313The string and integer information available for the CTL_KERN level 314is detailed below. 315The changeable column shows whether a process with appropriate 316privilege may change the value. 317The types of data currently available are process information, 318system vnodes, the open file entries, routing table entries, 319virtual memory statistics, load average history, and clock rate 320information. 321.Bl -column "KERNXMAXPOSIXLOCKSPERUIDXXX" "struct clockrateXXX" -offset indent 322.It Sy "Second level name Type Changeable" 323.It "KERN\_ARGMAX integer no" 324.It "KERN\_BOOTFILE string yes" 325.It "KERN\_BOOTTIME struct timeval no" 326.It "KERN\_CLOCKRATE struct clockinfo no" 327.It "KERN\_FILE struct file no" 328.It "KERN\_HOSTID integer yes" 329.It "KERN\_HOSTNAME string yes" 330.It "KERN\_JOB\_CONTROL integer no" 331.It "KERN\_MAXFILES integer yes" 332.It "KERN\_MAXFILESPERPROC integer yes" 333.It "KERN\_MAXPOSIXLOCKSPERUID integer yes" 334.It "KERN\_MAXPROC integer no" 335.It "KERN\_MAXPROCPERUID integer yes" 336.It "KERN\_MAXVNODES integer yes" 337.It "KERN\_NGROUPS integer no" 338.It "KERN\_NISDOMAINNAME string yes" 339.It "KERN\_OSRELDATE integer no" 340.It "KERN\_OSRELEASE string no" 341.It "KERN\_OSREV integer no" 342.It "KERN\_OSTYPE string no" 343.It "KERN\_POSIX1 integer no" 344.It "KERN\_PROC struct proc no" 345.It "KERN\_PROF node not applicable" 346.It "KERN\_QUANTUM integer yes" 347.It "KERN\_SAVED\_IDS integer no" 348.It "KERN\_SECURELVL integer raise only" 349.It "KERN\_UPDATEINTERVAL integer no" 350.It "KERN\_VERSION string no" 351.It "KERN\_VNODE struct vnode no" 352.El 353.Pp 354.Bl -tag -width 6n 355.It Li KERN_ARGMAX 356The maximum bytes of argument to 357.Xr execve 2 . 358.It Li KERN_BOOTFILE 359The full pathname of the file from which the kernel was loaded. 360.It Li KERN_BOOTTIME 361A 362.Va struct timeval 363structure is returned. 364This structure contains the time that the system was booted. 365.It Li KERN_CLOCKRATE 366A 367.Va struct clockinfo 368structure is returned. 369This structure contains the clock, statistics clock and profiling clock 370frequencies, the number of micro-seconds per hz tick and the skew rate. 371.It Li KERN_FILE 372Return the entire file table. 373The returned data consists of a single 374.Va struct filehead 375followed by an array of 376.Va struct file , 377whose size depends on the current number of such objects in the system. 378.It Li KERN_HOSTID 379Get or set the host id. 380.It Li KERN_HOSTNAME 381Get or set the hostname. 382.It Li KERN_JOB_CONTROL 383Return 1 if job control is available on this system, otherwise 0. 384.It Li KERN_MAXFILES 385The maximum number of files that may be open in the system. 386.It Li KERN_MAXFILESPERPROC 387The maximum number of files that may be open for a single process. 388This limit only applies to processes with an effective uid of nonzero 389at the time of the open request. 390Files that have already been opened are not affected if the limit 391or the effective uid is changed. 392.It Li KERN_MAXPROC 393The maximum number of concurrent processes the system will allow. 394.It Li KERN_MAXPROCPERUID 395The maximum number of concurrent processes the system will allow 396for a single effective uid. 397This limit only applies to processes with an effective uid of nonzero 398at the time of a fork request. 399Processes that have already been started are not affected if the limit 400is changed. 401.It Li KERN_MAXVNODES 402The maximum number of vnodes available on the system. 403.It Li KERN_NGROUPS 404The maximum number of supplemental groups. 405.It Li KERN_NISDOMAINNAME 406The name of the current YP/NIS domain. 407.It Li KERN_OSRELDATE 408The system release date in YYYYMM format 409(January 1996 is encoded as 199601). 410.It Li KERN_OSRELEASE 411The system release string. 412.It Li KERN_OSREV 413The system revision string. 414.It Li KERN_OSTYPE 415The system type string. 416.It Li KERN_POSIX1 417The version of 418.St -p1003.1 419with which the system 420attempts to comply. 421.It Li KERN_PROC 422Return the entire process table, or a subset of it. 423An array of 424.Va struct kinfo_proc 425structures is returned, 426whose size depends on the current number of such objects in the system. 427The third and fourth level names are as follows: 428.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 429.It "Third level name Fourth level is:" 430.It "KERN\_PROC\_ALL None" 431.It "KERN\_PROC\_PID A process ID" 432.It "KERN\_PROC\_PGRP A process group" 433.It "KERN\_PROC\_TTY A tty device" 434.It "KERN\_PROC\_UID A user ID" 435.It "KERN\_PROC\_RUID A real user ID" 436.El 437.Pp 438Adding the flag 439.Li KERN_PROC_FLAG_LWP 440to the third level name signals that information about all 441light weight processes of the selected processes should be returned. 442.It Li KERN_PROF 443Return profiling information about the kernel. 444If the kernel is not compiled for profiling, 445attempts to retrieve any of the KERN_PROF values will 446fail with 447.Er ENOENT . 448The third level names for the string and integer profiling information 449is detailed below. 450The changeable column shows whether a process with appropriate 451privilege may change the value. 452.Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent 453.It Sy "Third level name Type Changeable" 454.It "GPROF\_STATE integer yes" 455.It "GPROF\_COUNT u_short[\|] yes" 456.It "GPROF\_FROMS u_short[\|] yes" 457.It "GPROF\_TOS struct tostruct yes" 458.It "GPROF\_GMONPARAM struct gmonparam no" 459.El 460.Pp 461The variables are as follows: 462.Bl -tag -width 6n 463.It Li GPROF_STATE 464Returns GMON_PROF_ON or GMON_PROF_OFF to show that profiling 465is running or stopped. 466.It Li GPROF_COUNT 467Array of statistical program counter counts. 468.It Li GPROF_FROMS 469Array indexed by program counter of call-from points. 470.It Li GPROF_TOS 471Array of 472.Va struct tostruct 473describing destination of calls and their counts. 474.It Li GPROF_GMONPARAM 475Structure giving the sizes of the above arrays. 476.El 477.It Li KERN_QUANTUM 478The maximum period of time, in microseconds, for which a process is allowed 479to run without being preempted if other processes are in the run queue. 480.It Li KERN_SAVED_IDS 481Returns 1 if saved set-group and saved set-user ID is available. 482.It Li KERN_SECURELVL 483The system security level. 484This level may be raised by processes with appropriate privilege. 485It may not be lowered. 486.It Li KERN_VERSION 487The system version string. 488.It Li KERN_VNODE 489Return the entire vnode table. 490Note, the vnode table is not necessarily a consistent snapshot of 491the system. 492The returned data consists of an array whose size depends on the 493current number of such objects in the system. 494Each element of the array contains the kernel address of a vnode 495.Va struct vnode * 496followed by the vnode itself 497.Va struct vnode . 498.El 499.Ss CTL_MACHDEP 500The set of variables defined is architecture dependent. 501The following variables are defined for the i386 architecture. 502.Bl -column "CONSOLE_DEVICEXXX" "struct bootinfoXXX" -offset indent 503.It Sy "Second level name Type Changeable" 504.It Li "CPU_CONSDEV dev_t no" 505.It Li "CPU_ADJKERNTZ int yes" 506.It Li "CPU_DISRTCSET int yes" 507.It Li "CPU_BOOTINFO struct bootinfo no" 508.It Li "CPU_WALLCLOCK int yes" 509.El 510.Ss CTL_NET 511The string and integer information available for the CTL_NET level 512is detailed below. 513The changeable column shows whether a process with appropriate 514privilege may change the value. 515.Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent 516.It Sy "Second level name Type Changeable" 517.It "PF\_ROUTE routing messages no" 518.It "PF\_INET IPv4 values yes" 519.It "PF\_INET6 IPv6 values yes" 520.El 521.Pp 522.Bl -tag -width 6n 523.It Li PF_ROUTE 524Return the entire routing table or a subset of it. 525The data is returned as a sequence of routing messages (see 526.Xr route 4 527for the header file, format and meaning). 528The length of each message is contained in the message header. 529.Pp 530The third level name is a protocol number, which is currently always 0. 531The fourth level name is an address family, which may be set to 0 to 532select all address families. 533The fifth and sixth level names are as follows: 534.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent 535.It Sy "Fifth level name Sixth level is:" 536.It "NET\_RT\_FLAGS rtflags" 537.It "NET\_RT\_DUMP None" 538.It "NET\_RT\_IFLIST None" 539.El 540.It Li PF_INET 541Get or set various global information about the IPv4 542(Internet Protocol version 4). 543The third level name is the protocol. 544The fourth level name is the variable name. 545The currently defined protocols and names are: 546.Bl -column ProtocolXX VariableXX TypeXX ChangeableXX 547.It Sy "Protocol Variable Type Changeable" 548.It "icmp bmcastecho integer yes" 549.It "icmp maskrepl integer yes" 550.It "ip forwarding integer yes" 551.It "ip redirect integer yes" 552.It "ip ttl integer yes" 553.It "udp checksum integer yes" 554.El 555.Pp 556The variables are as follows: 557.Bl -tag -width 6n 558.It Li icmp.bmcastecho 559Returns 1 if an ICMP echo request to a broadcast or multicast address is 560to be answered. 561.It Li icmp.maskrepl 562Returns 1 if ICMP network mask requests are to be answered. 563.It Li ip.forwarding 564Returns 1 when IP forwarding is enabled for the host, 565meaning that the host is acting as a router. 566.It Li ip.redirect 567Returns 1 when ICMP redirects may be sent by the host. 568This option is ignored unless the host is routing IP packets, 569and should normally be enabled on all systems. 570.It Li ip.ttl 571The maximum time-to-live (hop count) value for an IP packet sourced by 572the system. 573This value applies to normal transport protocols, not to ICMP. 574.It Li udp.checksum 575Returns 1 when UDP checksums are being computed and checked. 576Disabling UDP checksums is strongly discouraged. 577.Pp 578For variables net.inet.*.ipsec, please refer to 579.Xr ipsec 4 . 580.El 581.It Li PF_INET6 582Get or set various global information about the IPv6 583(Internet Protocol version 6). 584The third level name is the protocol. 585The fourth level name is the variable name. 586.Pp 587For variables net.inet6.* please refer to 588.Xr inet6 4 . 589For variables net.inet6.*.ipsec6, please refer to 590.Xr ipsec 4 . 591.El 592.Ss CTL_USER 593The string and integer information available for the CTL_USER level 594is detailed below. 595The changeable column shows whether a process with appropriate 596privilege may change the value. 597.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 598.It Sy "Second level name Type Changeable" 599.It "USER\_BC\_BASE\_MAX integer no" 600.It "USER\_BC\_DIM\_MAX integer no" 601.It "USER\_BC\_SCALE\_MAX integer no" 602.It "USER\_BC\_STRING\_MAX integer no" 603.It "USER\_COLL\_WEIGHTS\_MAX integer no" 604.It "USER\_CS\_PATH string no" 605.It "USER\_EXPR\_NEST\_MAX integer no" 606.It "USER\_LINE\_MAX integer no" 607.It "USER\_POSIX2\_CHAR\_TERM integer no" 608.It "USER\_POSIX2\_C\_BIND integer no" 609.It "USER\_POSIX2\_C\_DEV integer no" 610.It "USER\_POSIX2\_FORT\_DEV integer no" 611.It "USER\_POSIX2\_FORT\_RUN integer no" 612.It "USER\_POSIX2\_LOCALEDEF integer no" 613.It "USER\_POSIX2\_SW\_DEV integer no" 614.It "USER\_POSIX2\_UPE integer no" 615.It "USER\_POSIX2\_VERSION integer no" 616.It "USER\_RE\_DUP\_MAX integer no" 617.It "USER\_STREAM\_MAX integer no" 618.It "USER\_TZNAME\_MAX integer no" 619.El 620.Bl -tag -width 6n 621.Pp 622.It Li USER_BC_BASE_MAX 623The maximum ibase/obase values in the 624.Xr bc 1 625utility. 626.It Li USER_BC_DIM_MAX 627The maximum array size in the 628.Xr bc 1 629utility. 630.It Li USER_BC_SCALE_MAX 631The maximum scale value in the 632.Xr bc 1 633utility. 634.It Li USER_BC_STRING_MAX 635The maximum string length in the 636.Xr bc 1 637utility. 638.It Li USER_COLL_WEIGHTS_MAX 639The maximum number of weights that can be assigned to any entry of 640the LC_COLLATE order keyword in the locale definition file. 641.It Li USER_CS_PATH 642Return a value for the 643.Ev PATH 644environment variable that finds all the standard utilities. 645.It Li USER_EXPR_NEST_MAX 646The maximum number of expressions that can be nested within 647parenthesis by the 648.Xr expr 1 649utility. 650.It Li USER_LINE_MAX 651The maximum length in bytes of a text-processing utility's input 652line. 653.It Li USER_POSIX2_CHAR_TERM 654Return 1 if the system supports at least one terminal type capable of 655all operations described in 656.St -p1003.2 , 657otherwise 0. 658.It Li USER_POSIX2_C_BIND 659Return 1 if the system's C-language development facilities support the 660C-Language Bindings Option, otherwise 0. 661.It Li USER_POSIX2_C_DEV 662Return 1 if the system supports the C-Language Development Utilities Option, 663otherwise 0. 664.It Li USER_POSIX2_FORT_DEV 665Return 1 if the system supports the FORTRAN Development Utilities Option, 666otherwise 0. 667.It Li USER_POSIX2_FORT_RUN 668Return 1 if the system supports the FORTRAN Runtime Utilities Option, 669otherwise 0. 670.It Li USER_POSIX2_LOCALEDEF 671Return 1 if the system supports the creation of locales, otherwise 0. 672.It Li USER_POSIX2_SW_DEV 673Return 1 if the system supports the Software Development Utilities Option, 674otherwise 0. 675.It Li USER_POSIX2_UPE 676Return 1 if the system supports the User Portability Utilities Option, 677otherwise 0. 678.It Li USER_POSIX2_VERSION 679The version of 680.St -p1003.2 681with which the system attempts to comply. 682.It Li USER_RE_DUP_MAX 683The maximum number of repeated occurrences of a regular expression 684permitted when using interval notation. 685.It Li USER_STREAM_MAX 686The minimum maximum number of streams that a process may have open 687at any one time. 688.It Li USER_TZNAME_MAX 689The minimum maximum number of types supported for the name of a 690timezone. 691.El 692.Ss CTL_VM 693The string and integer information available for the CTL_VM level 694is detailed below. 695The changeable column shows whether a process with appropriate 696privilege may change the value. 697.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 698.It Sy "Second level name Type Changeable" 699.It "VM\_LOADAVG struct loadavg no" 700.It "VM\_METER struct vmtotal no" 701.It "VM\_PAGEOUT\_ALGORITHM integer yes" 702.It "VM\_SWAPPING\_ENABLED integer maybe" 703.It "VM\_V\_CACHE\_MAX integer yes" 704.It "VM\_V\_CACHE\_MIN integer yes" 705.It "VM\_V\_FREE\_MIN integer yes" 706.It "VM\_V\_FREE\_RESERVED integer yes" 707.It "VM\_V\_FREE\_TARGET integer yes" 708.It "VM\_V\_INACTIVE\_TARGET integer yes" 709.It "VM\_V\_PAGEOUT\_FREE\_MIN integer yes" 710.El 711.Pp 712.Bl -tag -width 6n 713.It Li VM_LOADAVG 714Return the load average history. 715The returned data consists of a 716.Va struct loadavg . 717.It Li VM_METER 718Return the system wide virtual memory statistics. 719The returned data consists of a 720.Va struct vmtotal . 721.It Li VM_PAGEOUT_ALGORITHM 7220 if the statistics-based page management algorithm is in use 723or 1 if the near-LRU algorithm is in use. 724.It Li VM_SWAPPING_ENABLED 7251 if process swapping is enabled or 0 if disabled. This variable is 726permanently set to 0 if the kernel was built with swapping disabled. 727.It Li VM_V_CACHE_MAX 728Maximum desired size of the cache queue. 729.It Li VM_V_CACHE_MIN 730Minimum desired size of the cache queue. If the cache queue size 731falls very far below this value, the pageout daemon is awakened. 732.It Li VM_V_FREE_MIN 733Minimum amount of memory (cache memory plus free memory) 734required to be available before a process waiting on memory will be 735awakened. 736.It Li VM_V_FREE_RESERVED 737Processes will awaken the pageout daemon and wait for memory if the 738number of free and cached pages drops below this value. 739.It Li VM_V_FREE_TARGET 740The total amount of free memory (including cache memory) that the 741pageout daemon tries to maintain. 742.It Li VM_V_INACTIVE_TARGET 743The desired number of inactive pages that the pageout daemon should 744achieve when it runs. Inactive pages can be quickly inserted into 745process address space when needed. 746.It Li VM_V_PAGEOUT_FREE_MIN 747If the amount of free and cache memory falls below this value, the 748pageout daemon will enter "memory conserving mode" to avoid deadlock. 749.El 750.Sh RETURN VALUES 751.Rv -std 752.Sh FILES 753.Bl -tag -width ".In netinet/icmp_var.h" -compact 754.It In sys/sysctl.h 755definitions for top level identifiers, second level kernel and hardware 756identifiers, and user level identifiers 757.It In sys/socket.h 758definitions for second level network identifiers 759.It In sys/gmon.h 760definitions for third level profiling identifiers 761.It In vm/vm_param.h 762definitions for second level virtual memory identifiers 763.It In netinet/in.h 764definitions for third level IPv4/IPv6 identifiers and 765fourth level IPv4/v6 identifiers 766.It In netinet/icmp_var.h 767definitions for fourth level ICMP identifiers 768.It In netinet/icmp6.h 769definitions for fourth level ICMPv6 identifiers 770.It In netinet/udp_var.h 771definitions for fourth level UDP identifiers 772.El 773.Sh ERRORS 774The following errors may be reported: 775.Bl -tag -width Er 776.It Bq Er EFAULT 777The buffer 778.Fa name , 779.Fa oldp , 780.Fa newp , 781or length pointer 782.Fa oldlenp 783contains an invalid address. 784.It Bq Er EINVAL 785The 786.Fa name 787array is less than two or greater than CTL_MAXNAME. 788.It Bq Er EINVAL 789A non-null 790.Fa newp 791is given and its specified length in 792.Fa newlen 793is too large or too small. 794.It Bq Er ENOMEM 795The length pointed to by 796.Fa oldlenp 797is too short to hold the requested value. 798.It Bq Er ENOTDIR 799The 800.Fa name 801array specifies an intermediate rather than terminal name. 802.It Bq Er EISDIR 803The 804.Fa name 805array specifies a terminal name, but the actual name is not terminal. 806.It Bq Er ENOENT 807The 808.Fa name 809array specifies a value that is unknown. 810.It Bq Er EPERM 811An attempt is made to set a read-only value. 812.It Bq Er EPERM 813A process without appropriate privilege attempts to set a value. 814.El 815.Sh SEE ALSO 816.Xr sysconf 3 , 817.Xr sysctl 8 818.Sh HISTORY 819The 820.Fn sysctl 821function first appeared in 822.Bx 4.4 . 823