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.\" $FreeBSD$ 34.\" 35.Dd January 23, 2001 36.Dt SYSCTL 3 37.Os 38.Sh NAME 39.Nm sysctl , 40.Nm sysctlbyname , 41.Nm sysctlnametomib 42.Nd get or set system information 43.Sh LIBRARY 44.Lb libc 45.Sh SYNOPSIS 46.In sys/types.h 47.In sys/sysctl.h 48.Ft int 49.Fn sysctl "int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" 50.Ft int 51.Fn sysctlbyname "const char *name" "void *oldp" "size_t *oldlenp" "void *newp" "size_t newlen" 52.Ft int 53.Fn sysctlnametomib "const char *name" "int *mibp" "size_t *sizep" 54.Sh DESCRIPTION 55The 56.Fn sysctl 57function retrieves system information and allows processes with 58appropriate privileges to set system information. 59The information available from 60.Fn sysctl 61consists of integers, strings, and tables. 62Information may be retrieved and set from the command interface 63using the 64.Xr sysctl 8 65utility. 66.Pp 67Unless explicitly noted below, 68.Fn sysctl 69returns a consistent snapshot of the data requested. 70Consistency is obtained by locking the destination 71buffer into memory so that the data may be copied out without blocking. 72Calls to 73.Fn sysctl 74are serialized to avoid deadlock. 75.Pp 76The state is described using a ``Management Information Base'' (MIB) 77style name, listed in 78.Fa name , 79which is a 80.Fa namelen 81length array of integers. 82.Pp 83The 84.Fn sysctlbyname 85function accepts an ASCII representation of the name and internally 86looks up the integer name vector. Apart from that, it behaves the same 87as the standard 88.Fn sysctl 89function. 90.Pp 91The information is copied into the buffer specified by 92.Fa oldp . 93The size of the buffer is given by the location specified by 94.Fa oldlenp 95before the call, 96and that location gives the amount of data copied after a successful call 97and after a call that returns with the error code 98.Er ENOMEM . 99If the amount of data available is greater 100than the size of the buffer supplied, 101the call supplies as much data as fits in the buffer provided 102and returns with the error code 103.Er ENOMEM . 104If the old value is not desired, 105.Fa oldp 106and 107.Fa oldlenp 108should be set to NULL. 109.Pp 110The size of the available data can be determined by calling 111.Fn sysctl 112with the 113.Dv NULL 114argument for 115.Fa oldp . 116The size of the available data will be returned in the location pointed to by 117.Fa oldlenp . 118For some operations, the amount of space may change often. 119For these operations, 120the system attempts to round up so that the returned size is 121large enough for a call to return the data shortly thereafter. 122.Pp 123To set a new value, 124.Fa newp 125is set to point to a buffer of length 126.Fa newlen 127from which the requested value is to be taken. 128If a new value is not to be set, 129.Fa newp 130should be set to NULL and 131.Fa newlen 132set to 0. 133.Pp 134The 135.Fn sysctlnametomib 136function accepts an ASCII representation of the name, 137looks up the integer name vector, 138and returns the numeric representation in the mib array pointed to by 139.Fa mibp . 140The number of elements in the mib array is given by the location specified by 141.Fa sizep 142before the call, 143and that location gives the number of entries copied after a successful call. 144The resulting 145.Fa mib 146and 147.Fa size 148may be used in subsequent 149.Fn sysctl 150calls to get the data associated with the requested ASCII name. 151This interface is intended for use by applications that want to 152repeatedly request the same variable (the 153.Fn sysctl 154function runs in about a third the time as the same request made via the 155.Fn sysctlbyname 156function). 157The 158.Fn sysctlnametomib 159function is also useful for fetching mib prefixes and then adding 160a final component. 161For example, to fetch process information 162for processes with pid's less than 100: 163.Pp 164.Bd -literal -offset indent -compact 165int i, mib[4]; 166size_t len; 167struct kinfo_proc kp; 168 169/* Fill out the first three components of the mib */ 170len = 4; 171sysctlnametomib("kern.proc.pid", mib, &len); 172 173/* Fetch and print entries for pid's < 100 */ 174for (i = 0; i < 100; i++) { 175 mib[3] = i; 176 len = sizeof(kp); 177 if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1) 178 perror("sysctl"); 179 else if (len > 0) 180 printkproc(&kp); 181} 182.Ed 183.Pp 184The top level names are defined with a CTL_ prefix in 185.Aq Pa sys/sysctl.h , 186and are as follows. 187The next and subsequent levels down are found in the include files 188listed here, and described in separate sections below. 189.Pp 190.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent 191.It Sy "Name Next level names Description" 192.It "CTL\_DEBUG sys/sysctl.h Debugging" 193.It "CTL\_VFS sys/mount.h File system" 194.It "CTL\_HW sys/sysctl.h Generic CPU, I/O" 195.It "CTL\_KERN sys/sysctl.h High kernel limits" 196.It "CTL\_MACHDEP sys/sysctl.h Machine dependent" 197.It "CTL\_NET sys/socket.h Networking" 198.It "CTL\_USER sys/sysctl.h User-level" 199.It "CTL\_VM vm/vm_param.h Virtual memory" 200.El 201.Pp 202For example, the following retrieves the maximum number of processes allowed 203in the system: 204.Pp 205.Bd -literal -offset indent -compact 206int mib[2], maxproc; 207size_t len; 208 209mib[0] = CTL_KERN; 210mib[1] = KERN_MAXPROC; 211len = sizeof(maxproc); 212sysctl(mib, 2, &maxproc, &len, NULL, 0); 213.Ed 214.Pp 215To retrieve the standard search path for the system utilities: 216.Pp 217.Bd -literal -offset indent -compact 218int mib[2]; 219size_t len; 220char *p; 221 222mib[0] = CTL_USER; 223mib[1] = USER_CS_PATH; 224sysctl(mib, 2, NULL, &len, NULL, 0); 225p = malloc(len); 226sysctl(mib, 2, p, &len, NULL, 0); 227.Ed 228.Ss CTL_DEBUG 229The debugging variables vary from system to system. 230A debugging variable may be added or deleted without need to recompile 231.Fn sysctl 232to know about it. 233Each time it runs, 234.Fn sysctl 235gets the list of debugging variables from the kernel and 236displays their current values. 237The system defines twenty 238.Pq Vt "struct ctldebug" 239variables named 240.Va debug0 241through 242.Va debug19 . 243They are declared as separate variables so that they can be 244individually initialized at the location of their associated variable. 245The loader prevents multiple use of the same variable by issuing errors 246if a variable is initialized in more than one place. 247For example, to export the variable 248.Va dospecialcheck 249as a debugging variable, the following declaration would be used: 250.Pp 251.Bd -literal -offset indent -compact 252int dospecialcheck = 1; 253struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck }; 254.Ed 255.Ss CTL_VFS 256A distinguished second level name, VFS_GENERIC, 257is used to get general information about all file systems. 258One of its third level identifiers is VFS_MAXTYPENUM 259that gives the highest valid file system type number. 260Its other third level identifier is VFS_CONF that 261returns configuration information about the file system 262type given as a fourth level identifier (see 263.Xr getvfsbyname 3 264as an example of its use). 265The remaining second level identifiers are the 266file system type number returned by a 267.Xr statfs 2 268call or from VFS_CONF. 269The third level identifiers available for each file system 270are given in the header file that defines the mount 271argument structure for that file system. 272.Ss CTL_HW 273The string and integer information available for the CTL_HW level 274is detailed below. 275The changeable column shows whether a process with appropriate 276privilege may change the value. 277.Bl -column "Second level nameXXXXXX" integerXXX -offset indent 278.It Sy "Second level name Type Changeable" 279.It "HW\_MACHINE string no" 280.It "HW\_MODEL string no" 281.It "HW\_NCPU integer no" 282.It "HW\_BYTEORDER integer no" 283.It "HW\_PHYSMEM integer no" 284.It "HW\_USERMEM integer no" 285.It "HW\_PAGESIZE integer no" 286.It "HW\_FLOATINGPOINT integer no" 287.It "HW\_MACHINE\_ARCH string no" 288.\".It "HW\_DISKNAMES integer no" 289.\".It "HW\_DISKSTATS integer no" 290.El 291.Pp 292.Bl -tag -width 6n 293.It Li HW_MACHINE 294The machine class. 295.It Li HW_MODEL 296The machine model 297.It Li HW_NCPU 298The number of cpus. 299.It Li HW_BYTEORDER 300The byteorder (4,321, or 1,234). 301.It Li HW_PHYSMEM 302The bytes of physical memory. 303.It Li HW_USERMEM 304The bytes of non-kernel memory. 305.It Li HW_PAGESIZE 306The software page size. 307.It Li HW_FLOATINGPOINT 308Nonzero if the floating point support is in hardware. 309.It Li HW_MACHINE_ARCH 310The machine dependent architecture type. 311.\".It Fa HW_DISKNAMES 312.\".It Fa HW_DISKSTATS 313.El 314.Ss CTL_KERN 315The string and integer information available for the CTL_KERN level 316is detailed below. 317The changeable column shows whether a process with appropriate 318privilege may change the value. 319The types of data currently available are process information, 320system vnodes, the open file entries, routing table entries, 321virtual memory statistics, load average history, and clock rate 322information. 323.Bl -column "KERNXMAXFILESPERPROCXXX" "struct clockrateXXX" -offset indent 324.It Sy "Second level name Type Changeable" 325.It "KERN\_ARGMAX integer no" 326.It "KERN\_BOOTFILE string yes" 327.It "KERN\_BOOTTIME struct timeval no" 328.It "KERN\_CLOCKRATE struct clockinfo no" 329.It "KERN\_FILE struct file no" 330.It "KERN\_HOSTID integer yes" 331.It "KERN\_HOSTNAME string yes" 332.It "KERN\_JOB\_CONTROL integer no" 333.It "KERN\_MAXFILES integer yes" 334.It "KERN\_MAXFILESPERPROC integer yes" 335.It "KERN\_MAXPROC integer no" 336.It "KERN\_MAXPROCPERUID integer yes" 337.It "KERN\_MAXVNODES integer yes" 338.It "KERN\_NGROUPS integer no" 339.It "KERN\_NISDOMAINNAME string yes" 340.It "KERN\_OSRELDATE integer no" 341.It "KERN\_OSRELEASE string no" 342.It "KERN\_OSREV integer no" 343.It "KERN\_OSTYPE string no" 344.It "KERN\_POSIX1 integer no" 345.It "KERN\_PROC struct proc no" 346.It "KERN\_PROF node not applicable" 347.It "KERN\_QUANTUM integer yes" 348.It "KERN\_SAVED\_IDS integer no" 349.It "KERN\_SECURELVL integer raise only" 350.It "KERN\_UPDATEINTERVAL integer no" 351.It "KERN\_VERSION string no" 352.It "KERN\_VNODE struct vnode no" 353.El 354.Pp 355.Bl -tag -width 6n 356.It Li KERN_ARGMAX 357The maximum bytes of argument to 358.Xr execve 2 . 359.It Li KERN_BOOTFILE 360The full pathname of the file from which the kernel was loaded. 361.It Li KERN_BOOTTIME 362A 363.Va struct timeval 364structure is returned. 365This structure contains the time that the system was booted. 366.It Li KERN_CLOCKRATE 367A 368.Va struct clockinfo 369structure is returned. 370This structure contains the clock, statistics clock and profiling clock 371frequencies, the number of micro-seconds per hz tick and the skew rate. 372.It Li KERN_FILE 373Return the entire file table. 374The returned data consists of a single 375.Va struct filehead 376followed by an array of 377.Va struct file , 378whose size depends on the current number of such objects in the system. 379.It Li KERN_HOSTID 380Get or set the host id. 381.It Li KERN_HOSTNAME 382Get or set the hostname. 383.It Li KERN_JOB_CONTROL 384Return 1 if job control is available on this system, otherwise 0. 385.It Li KERN_MAXFILES 386The maximum number of files that may be open in the system. 387.It Li KERN_MAXFILESPERPROC 388The maximum number of files that may be open for a single process. 389This limit only applies to processes with an effective uid of nonzero 390at the time of the open request. 391Files that have already been opened are not affected if the limit 392or the effective uid is changed. 393.It Li KERN_MAXPROC 394The maximum number of concurrent processes the system will allow. 395.It Li KERN_MAXPROCPERUID 396The maximum number of concurrent processes the system will allow 397for a single effective uid. 398This limit only applies to processes with an effective uid of nonzero 399at the time of a fork request. 400Processes that have already been started are not affected if the limit 401is changed. 402.It Li KERN_MAXVNODES 403The maximum number of vnodes available on the system. 404.It Li KERN_NGROUPS 405The maximum number of supplemental groups. 406.It Li KERN_NISDOMAINNAME 407The name of the current YP/NIS domain. 408.It Li KERN_OSRELDATE 409The system release date in YYYYMM format 410(January 1996 is encoded as 199601). 411.It Li KERN_OSRELEASE 412The system release string. 413.It Li KERN_OSREV 414The system revision string. 415.It Li KERN_OSTYPE 416The system type string. 417.It Li KERN_POSIX1 418The version of 419.St -p1003.1 420with which the system 421attempts to comply. 422.It Li KERN_PROC 423Return the entire process table, or a subset of it. 424An array of pairs of 425.Va struct proc 426followed by corresponding 427.Va struct eproc 428structures is returned, 429whose size depends on the current number of such objects in the system. 430The third and fourth level names are as follows: 431.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 432.It "Third level name Fourth level is:" 433.It "KERN\_PROC\_ALL None" 434.It "KERN\_PROC\_PID A process ID" 435.It "KERN\_PROC\_PGRP A process group" 436.It "KERN\_PROC\_TTY A tty device" 437.It "KERN\_PROC\_UID A user ID" 438.It "KERN\_PROC\_RUID A real user ID" 439.El 440.Pp 441If the third level name is KERN_PROC_ARGS then the command line argument 442array is returned in a flattened form, i.e. zero-terminated arguments 443follow each other. 444The total size of array is returned. 445It is also possible for a process to set its own process title this way. 446.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 447.It Sy "Third level name Fourth level is:" 448.It "KERN\_PROC\_ARGS A process ID" 449.El 450.It Li KERN_PROF 451Return profiling information about the kernel. 452If the kernel is not compiled for profiling, 453attempts to retrieve any of the KERN_PROF values will 454fail with 455.Er ENOENT . 456The third level names for the string and integer profiling information 457is detailed below. 458The changeable column shows whether a process with appropriate 459privilege may change the value. 460.Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent 461.It Sy "Third level name Type Changeable" 462.It "GPROF\_STATE integer yes" 463.It "GPROF\_COUNT u_short[\|] yes" 464.It "GPROF\_FROMS u_short[\|] yes" 465.It "GPROF\_TOS struct tostruct yes" 466.It "GPROF\_GMONPARAM struct gmonparam no" 467.El 468.Pp 469The variables are as follows: 470.Bl -tag -width 6n 471.It Li GPROF_STATE 472Returns GMON_PROF_ON or GMON_PROF_OFF to show that profiling 473is running or stopped. 474.It Li GPROF_COUNT 475Array of statistical program counter counts. 476.It Li GPROF_FROMS 477Array indexed by program counter of call-from points. 478.It Li GPROF_TOS 479Array of 480.Va struct tostruct 481describing destination of calls and their counts. 482.It Li GPROF_GMONPARAM 483Structure giving the sizes of the above arrays. 484.El 485.It Li KERN_QUANTUM 486The maximum period of time, in microseconds, for which a process is allowed 487to run without being preempted if other processes are in the run queue. 488.It Li KERN_SAVED_IDS 489Returns 1 if saved set-group and saved set-user ID is available. 490.It Li KERN_SECURELVL 491The system security level. 492This level may be raised by processes with appropriate privilege. 493It may not be lowered. 494.It Li KERN_VERSION 495The system version string. 496.It Li KERN_VNODE 497Return the entire vnode table. 498Note, the vnode table is not necessarily a consistent snapshot of 499the system. 500The returned data consists of an array whose size depends on the 501current number of such objects in the system. 502Each element of the array contains the kernel address of a vnode 503.Va struct vnode * 504followed by the vnode itself 505.Va struct vnode . 506.El 507.Ss CTL_MACHDEP 508The set of variables defined is architecture dependent. 509The following variables are defined for the i386 architecture. 510.Bl -column "CONSOLE_DEVICEXXX" "struct bootinfoXXX" -offset indent 511.It Sy "Second level name Type Changeable" 512.It Li "CPU_CONSDEV dev_t no" 513.It Li "CPU_ADJKERNTZ int yes" 514.It Li "CPU_DISRTCSET int yes" 515.It Li "CPU_BOOTINFO struct bootinfo no" 516.It Li "CPU_WALLCLOCK int yes" 517.El 518.Ss CTL_NET 519The string and integer information available for the CTL_NET level 520is detailed below. 521The changeable column shows whether a process with appropriate 522privilege may change the value. 523.Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent 524.It Sy "Second level name Type Changeable" 525.It "PF\_ROUTE routing messages no" 526.It "PF\_INET IPv4 values yes" 527.It "PF\_INET6 IPv6 values yes" 528.El 529.Pp 530.Bl -tag -width 6n 531.It Li PF_ROUTE 532Return the entire routing table or a subset of it. 533The data is returned as a sequence of routing messages (see 534.Xr route 4 535for the header file, format and meaning). 536The length of each message is contained in the message header. 537.Pp 538The third level name is a protocol number, which is currently always 0. 539The fourth level name is an address family, which may be set to 0 to 540select all address families. 541The fifth and sixth level names are as follows: 542.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent 543.It Sy "Fifth level name Sixth level is:" 544.It "NET\_RT\_FLAGS rtflags" 545.It "NET\_RT\_DUMP None" 546.It "NET\_RT\_IFLIST 0 or if_index" 547.El 548.It Li PF_INET 549Get or set various global information about the IPv4 550(Internet Protocol version 4). 551The third level name is the protocol. 552The fourth level name is the variable name. 553The currently defined protocols and names are: 554.Bl -column ProtocolXX VariableXX TypeXX ChangeableXX 555.It Sy "Protocol Variable Type Changeable" 556.It "icmp bmcastecho integer yes" 557.It "icmp maskrepl integer yes" 558.It "ip forwarding integer yes" 559.It "ip redirect integer yes" 560.It "ip ttl integer yes" 561.It "udp checksum integer yes" 562.El 563.Pp 564The variables are as follows: 565.Bl -tag -width 6n 566.It Li icmp.bmcastecho 567Returns 1 if an ICMP echo request to a broadcast or multicast address is 568to be answered. 569.It Li icmp.maskrepl 570Returns 1 if ICMP network mask requests are to be answered. 571.It Li ip.forwarding 572Returns 1 when IP forwarding is enabled for the host, 573meaning that the host is acting as a router. 574.It Li ip.redirect 575Returns 1 when ICMP redirects may be sent by the host. 576This option is ignored unless the host is routing IP packets, 577and should normally be enabled on all systems. 578.It Li ip.ttl 579The maximum time-to-live (hop count) value for an IP packet sourced by 580the system. 581This value applies to normal transport protocols, not to ICMP. 582.It Li udp.checksum 583Returns 1 when UDP checksums are being computed and checked. 584Disabling UDP checksums is strongly discouraged. 585.Pp 586For variables net.inet.*.ipsec, please refer to 587.Xr ipsec 4 . 588.El 589.It Li PF_INET6 590Get or set various global information about the IPv6 591(Internet Protocol version 6). 592The third level name is the protocol. 593The fourth level name is the variable name. 594.Pp 595For variables net.inet6.* please refer to 596.Xr inet6 4 . 597For variables net.inet6.*.ipsec6, please refer to 598.Xr ipsec 4 . 599.El 600.Ss CTL_USER 601The string and integer information available for the CTL_USER level 602is detailed below. 603The changeable column shows whether a process with appropriate 604privilege may change the value. 605.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 606.It Sy "Second level name Type Changeable" 607.It "USER\_BC\_BASE\_MAX integer no" 608.It "USER\_BC\_DIM\_MAX integer no" 609.It "USER\_BC\_SCALE\_MAX integer no" 610.It "USER\_BC\_STRING\_MAX integer no" 611.It "USER\_COLL\_WEIGHTS\_MAX integer no" 612.It "USER\_CS\_PATH string no" 613.It "USER\_EXPR\_NEST\_MAX integer no" 614.It "USER\_LINE\_MAX integer no" 615.It "USER\_POSIX2\_CHAR\_TERM integer no" 616.It "USER\_POSIX2\_C\_BIND integer no" 617.It "USER\_POSIX2\_C\_DEV integer no" 618.It "USER\_POSIX2\_FORT\_DEV integer no" 619.It "USER\_POSIX2\_FORT\_RUN integer no" 620.It "USER\_POSIX2\_LOCALEDEF integer no" 621.It "USER\_POSIX2\_SW\_DEV integer no" 622.It "USER\_POSIX2\_UPE integer no" 623.It "USER\_POSIX2\_VERSION integer no" 624.It "USER\_RE\_DUP\_MAX integer no" 625.It "USER\_STREAM\_MAX integer no" 626.It "USER\_TZNAME\_MAX integer no" 627.El 628.Bl -tag -width 6n 629.Pp 630.It Li USER_BC_BASE_MAX 631The maximum ibase/obase values in the 632.Xr bc 1 633utility. 634.It Li USER_BC_DIM_MAX 635The maximum array size in the 636.Xr bc 1 637utility. 638.It Li USER_BC_SCALE_MAX 639The maximum scale value in the 640.Xr bc 1 641utility. 642.It Li USER_BC_STRING_MAX 643The maximum string length in the 644.Xr bc 1 645utility. 646.It Li USER_COLL_WEIGHTS_MAX 647The maximum number of weights that can be assigned to any entry of 648the LC_COLLATE order keyword in the locale definition file. 649.It Li USER_CS_PATH 650Return a value for the 651.Ev PATH 652environment variable that finds all the standard utilities. 653.It Li USER_EXPR_NEST_MAX 654The maximum number of expressions that can be nested within 655parenthesis by the 656.Xr expr 1 657utility. 658.It Li USER_LINE_MAX 659The maximum length in bytes of a text-processing utility's input 660line. 661.It Li USER_POSIX2_CHAR_TERM 662Return 1 if the system supports at least one terminal type capable of 663all operations described in 664.St -p1003.2 , 665otherwise 0. 666.It Li USER_POSIX2_C_BIND 667Return 1 if the system's C-language development facilities support the 668C-Language Bindings Option, otherwise 0. 669.It Li USER_POSIX2_C_DEV 670Return 1 if the system supports the C-Language Development Utilities Option, 671otherwise 0. 672.It Li USER_POSIX2_FORT_DEV 673Return 1 if the system supports the FORTRAN Development Utilities Option, 674otherwise 0. 675.It Li USER_POSIX2_FORT_RUN 676Return 1 if the system supports the FORTRAN Runtime Utilities Option, 677otherwise 0. 678.It Li USER_POSIX2_LOCALEDEF 679Return 1 if the system supports the creation of locales, otherwise 0. 680.It Li USER_POSIX2_SW_DEV 681Return 1 if the system supports the Software Development Utilities Option, 682otherwise 0. 683.It Li USER_POSIX2_UPE 684Return 1 if the system supports the User Portability Utilities Option, 685otherwise 0. 686.It Li USER_POSIX2_VERSION 687The version of 688.St -p1003.2 689with which the system attempts to comply. 690.It Li USER_RE_DUP_MAX 691The maximum number of repeated occurrences of a regular expression 692permitted when using interval notation. 693.It Li USER_STREAM_MAX 694The minimum maximum number of streams that a process may have open 695at any one time. 696.It Li USER_TZNAME_MAX 697The minimum maximum number of types supported for the name of a 698timezone. 699.El 700.Ss CTL_VM 701The string and integer information available for the CTL_VM level 702is detailed below. 703The changeable column shows whether a process with appropriate 704privilege may change the value. 705.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 706.It Sy "Second level name Type Changeable" 707.It "VM\_LOADAVG struct loadavg no" 708.It "VM\_METER struct vmtotal no" 709.It "VM\_PAGEOUT\_ALGORITHM integer yes" 710.It "VM\_SWAPPING\_ENABLED integer maybe" 711.It "VM\_V\_CACHE\_MAX integer yes" 712.It "VM\_V\_CACHE\_MIN integer yes" 713.It "VM\_V\_FREE\_MIN integer yes" 714.It "VM\_V\_FREE\_RESERVED integer yes" 715.It "VM\_V\_FREE\_TARGET integer yes" 716.It "VM\_V\_INACTIVE\_TARGET integer yes" 717.It "VM\_V\_PAGEOUT\_FREE\_MIN integer yes" 718.El 719.Pp 720.Bl -tag -width 6n 721.It Li VM_LOADAVG 722Return the load average history. 723The returned data consists of a 724.Va struct loadavg . 725.It Li VM_METER 726Return the system wide virtual memory statistics. 727The returned data consists of a 728.Va struct vmtotal . 729.It Li VM_PAGEOUT_ALGORITHM 7300 if the statistics-based page management algorithm is in use 731or 1 if the near-LRU algorithm is in use. 732.It Li VM_SWAPPING_ENABLED 7331 if process swapping is enabled or 0 if disabled. This variable is 734permanently set to 0 if the kernel was built with swapping disabled. 735.It Li VM_V_CACHE_MAX 736Maximum desired size of the cache queue. 737.It Li VM_V_CACHE_MIN 738Minimum desired size of the cache queue. If the cache queue size 739falls very far below this value, the pageout daemon is awakened. 740.It Li VM_V_FREE_MIN 741Minimum amount of memory (cache memory plus free memory) 742required to be available before a process waiting on memory will be 743awakened. 744.It Li VM_V_FREE_RESERVED 745Processes will awaken the pageout daemon and wait for memory if the 746number of free and cached pages drops below this value. 747.It Li VM_V_FREE_TARGET 748The total amount of free memory (including cache memory) that the 749pageout daemon tries to maintain. 750.It Li VM_V_INACTIVE_TARGET 751The desired number of inactive pages that the pageout daemon should 752achieve when it runs. Inactive pages can be quickly inserted into 753process address space when needed. 754.It Li VM_V_PAGEOUT_FREE_MIN 755If the amount of free and cache memory falls below this value, the 756pageout daemon will enter "memory conserving mode" to avoid deadlock. 757.El 758.Sh RETURN VALUES 759.Rv -std 760.Sh ERRORS 761The following errors may be reported: 762.Bl -tag -width Er 763.It Bq Er EFAULT 764The buffer 765.Fa name , 766.Fa oldp , 767.Fa newp , 768or length pointer 769.Fa oldlenp 770contains an invalid address. 771.It Bq Er EINVAL 772The 773.Fa name 774array is less than two or greater than CTL_MAXNAME. 775.It Bq Er EINVAL 776A non-null 777.Fa newp 778is given and its specified length in 779.Fa newlen 780is too large or too small. 781.It Bq Er ENOMEM 782The length pointed to by 783.Fa oldlenp 784is too short to hold the requested value. 785.It Bq Er ENOTDIR 786The 787.Fa name 788array specifies an intermediate rather than terminal name. 789.It Bq Er EISDIR 790The 791.Fa name 792array specifies a terminal name, but the actual name is not terminal. 793.It Bq Er ENOENT 794The 795.Fa name 796array specifies a value that is unknown. 797.It Bq Er EPERM 798An attempt is made to set a read-only value. 799.It Bq Er EPERM 800A process without appropriate privilege attempts to set a value. 801.El 802.Sh FILES 803.Bl -tag -width <netinet/icmpXvar.h> -compact 804.It Aq Pa sys/sysctl.h 805definitions for top level identifiers, second level kernel and hardware 806identifiers, and user level identifiers 807.It Aq Pa sys/socket.h 808definitions for second level network identifiers 809.It Aq Pa sys/gmon.h 810definitions for third level profiling identifiers 811.It Aq Pa vm/vm_param.h 812definitions for second level virtual memory identifiers 813.It Aq Pa netinet/in.h 814definitions for third level IPv4/IPv6 identifiers and 815fourth level IPv4/v6 identifiers 816.It Aq Pa netinet/icmp_var.h 817definitions for fourth level ICMP identifiers 818.It Aq Pa netinet/icmp6.h 819definitions for fourth level ICMPv6 identifiers 820.It Aq Pa netinet/udp_var.h 821definitions for fourth level UDP identifiers 822.El 823.Sh SEE ALSO 824.Xr sysconf 3 , 825.Xr sysctl 8 826.Sh HISTORY 827The 828.Fn sysctl 829function first appeared in 830.Bx 4.4 . 831