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. 87Apart 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 the 114.Dv NULL 115argument for 116.Fa oldp . 117The size of the available data will be returned in the location pointed to by 118.Fa oldlenp . 119For some operations, the amount of space may change often. 120For these operations, 121the system attempts to round up so that the returned size is 122large enough for a call to return the data shortly thereafter. 123.Pp 124To set a new value, 125.Fa newp 126is set to point to a buffer of length 127.Fa newlen 128from which the requested value is to be taken. 129If a new value is not to be set, 130.Fa newp 131should be set to NULL and 132.Fa newlen 133set to 0. 134.Pp 135The 136.Fn sysctlnametomib 137function accepts an ASCII representation of the name, 138looks up the integer name vector, 139and returns the numeric representation in the mib array pointed to by 140.Fa mibp . 141The number of elements in the mib array is given by the location specified by 142.Fa sizep 143before the call, 144and that location gives the number of entries copied after a successful call. 145The resulting 146.Fa mib 147and 148.Fa size 149may be used in subsequent 150.Fn sysctl 151calls to get the data associated with the requested ASCII name. 152This interface is intended for use by applications that want to 153repeatedly request the same variable (the 154.Fn sysctl 155function runs in about a third the time as the same request made via the 156.Fn sysctlbyname 157function). 158The 159.Fn sysctlnametomib 160function is also useful for fetching mib prefixes and then adding 161a final component. 162For example, to fetch process information 163for processes with pid's less than 100: 164.Pp 165.Bd -literal -offset indent -compact 166int i, mib[4]; 167size_t len; 168struct kinfo_proc kp; 169 170/* Fill out the first three components of the mib */ 171len = 4; 172sysctlnametomib("kern.proc.pid", mib, &len); 173 174/* Fetch and print entries for pid's < 100 */ 175for (i = 0; i < 100; i++) { 176 mib[3] = i; 177 len = sizeof(kp); 178 if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1) 179 perror("sysctl"); 180 else if (len > 0) 181 printkproc(&kp); 182} 183.Ed 184.Pp 185The top level names are defined with a CTL_ prefix in 186.In sys/sysctl.h , 187and are as follows. 188The next and subsequent levels down are found in the include files 189listed here, and described in separate sections below. 190.Pp 191.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent 192.It Sy "Name Next level names Description" 193.It "CTL_DEBUG sys/sysctl.h Debugging" 194.It "CTL_VFS sys/mount.h File system" 195.It "CTL_HW sys/sysctl.h Generic CPU, I/O" 196.It "CTL_KERN sys/sysctl.h High kernel limits" 197.It "CTL_MACHDEP sys/sysctl.h Machine dependent" 198.It "CTL_NET sys/socket.h Networking" 199.It "CTL_USER sys/sysctl.h User-level" 200.It "CTL_VM vm/vm_param.h Virtual memory" 201.El 202.Pp 203For example, the following retrieves the maximum number of processes allowed 204in the system: 205.Pp 206.Bd -literal -offset indent -compact 207int mib[2], maxproc; 208size_t len; 209 210mib[0] = CTL_KERN; 211mib[1] = KERN_MAXPROC; 212len = sizeof(maxproc); 213sysctl(mib, 2, &maxproc, &len, NULL, 0); 214.Ed 215.Pp 216To retrieve the standard search path for the system utilities: 217.Pp 218.Bd -literal -offset indent -compact 219int mib[2]; 220size_t len; 221char *p; 222 223mib[0] = CTL_USER; 224mib[1] = USER_CS_PATH; 225sysctl(mib, 2, NULL, &len, NULL, 0); 226p = malloc(len); 227sysctl(mib, 2, p, &len, NULL, 0); 228.Ed 229.Ss CTL_DEBUG 230The debugging variables vary from system to system. 231A debugging variable may be added or deleted without need to recompile 232.Fn sysctl 233to know about it. 234Each time it runs, 235.Fn sysctl 236gets the list of debugging variables from the kernel and 237displays their current values. 238The system defines twenty 239.Pq Vt "struct ctldebug" 240variables named 241.Va debug0 242through 243.Va debug19 . 244They are declared as separate variables so that they can be 245individually initialized at the location of their associated variable. 246The loader prevents multiple use of the same variable by issuing errors 247if a variable is initialized in more than one place. 248For example, to export the variable 249.Va dospecialcheck 250as a debugging variable, the following declaration would be used: 251.Pp 252.Bd -literal -offset indent -compact 253int dospecialcheck = 1; 254struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck }; 255.Ed 256.Ss CTL_VFS 257A distinguished second level name, VFS_GENERIC, 258is used to get general information about all file systems. 259One of its third level identifiers is VFS_MAXTYPENUM 260that gives the highest valid file system type number. 261Its other third level identifier is VFS_CONF that 262returns configuration information about the file system 263type given as a fourth level identifier (see 264.Xr getvfsbyname 3 265as an example of its use). 266The remaining second level identifiers are the 267file system type number returned by a 268.Xr statfs 2 269call or from VFS_CONF. 270The third level identifiers available for each file system 271are given in the header file that defines the mount 272argument structure for that file system. 273.Ss CTL_HW 274The string and integer information available for the CTL_HW level 275is detailed below. 276The changeable column shows whether a process with appropriate 277privilege may change the value. 278.Bl -column "Second level nameXXXXXX" integerXXX -offset indent 279.It Sy "Second level name Type Changeable" 280.It "HW_MACHINE string no" 281.It "HW_MODEL string no" 282.It "HW_NCPU integer no" 283.It "HW_BYTEORDER integer no" 284.It "HW_PHYSMEM integer no" 285.It "HW_USERMEM integer no" 286.It "HW_PAGESIZE integer no" 287.It "HW_FLOATINGPOINT integer no" 288.It "HW_MACHINE_ARCH string no" 289.\".It "HW_DISKNAMES integer no" 290.\".It "HW_DISKSTATS integer no" 291.El 292.Pp 293.Bl -tag -width 6n 294.It Li HW_MACHINE 295The machine class. 296.It Li HW_MODEL 297The machine model 298.It Li HW_NCPU 299The number of cpus. 300.It Li HW_BYTEORDER 301The byteorder (4,321, or 1,234). 302.It Li HW_PHYSMEM 303The bytes of physical memory. 304.It Li HW_USERMEM 305The bytes of non-kernel memory. 306.It Li HW_PAGESIZE 307The software page size. 308.It Li HW_FLOATINGPOINT 309Nonzero if the floating point support is in hardware. 310.It Li HW_MACHINE_ARCH 311The machine dependent architecture type. 312.\".It Fa HW_DISKNAMES 313.\".It Fa HW_DISKSTATS 314.El 315.Ss CTL_KERN 316The string and integer information available for the CTL_KERN level 317is detailed below. 318The changeable column shows whether a process with appropriate 319privilege may change the value. 320The types of data currently available are process information, 321system vnodes, the open file entries, routing table entries, 322virtual memory statistics, load average history, and clock rate 323information. 324.Bl -column "KERNXMAXFILESPERPROCXXX" "struct clockrateXXX" -offset indent 325.It Sy "Second level name Type Changeable" 326.It "KERN_ARGMAX integer no" 327.It "KERN_BOOTFILE string yes" 328.It "KERN_BOOTTIME struct timeval no" 329.It "KERN_CLOCKRATE struct clockinfo no" 330.It "KERN_FILE struct file no" 331.It "KERN_HOSTID integer yes" 332.It "KERN_HOSTNAME string yes" 333.It "KERN_JOB_CONTROL integer no" 334.It "KERN_MAXFILES integer yes" 335.It "KERN_MAXFILESPERPROC integer yes" 336.It "KERN_MAXPROC integer no" 337.It "KERN_MAXPROCPERUID integer yes" 338.It "KERN_MAXVNODES integer yes" 339.It "KERN_NGROUPS integer no" 340.It "KERN_NISDOMAINNAME string yes" 341.It "KERN_OSRELDATE integer no" 342.It "KERN_OSRELEASE string no" 343.It "KERN_OSREV integer no" 344.It "KERN_OSTYPE string no" 345.It "KERN_POSIX1 integer no" 346.It "KERN_PROC struct proc no" 347.It "KERN_PROF node not applicable" 348.It "KERN_QUANTUM integer yes" 349.It "KERN_SAVED_IDS integer no" 350.It "KERN_SECURELVL integer raise only" 351.It "KERN_UPDATEINTERVAL integer no" 352.It "KERN_VERSION string no" 353.It "KERN_VNODE struct vnode no" 354.El 355.Pp 356.Bl -tag -width 6n 357.It Li KERN_ARGMAX 358The maximum bytes of argument to 359.Xr execve 2 . 360.It Li KERN_BOOTFILE 361The full pathname of the file from which the kernel was loaded. 362.It Li KERN_BOOTTIME 363A 364.Va struct timeval 365structure is returned. 366This structure contains the time that the system was booted. 367.It Li KERN_CLOCKRATE 368A 369.Va struct clockinfo 370structure is returned. 371This structure contains the clock, statistics clock and profiling clock 372frequencies, the number of micro-seconds per hz tick and the skew rate. 373.It Li KERN_FILE 374Return the entire file table. 375The returned data consists of a single 376.Va struct filehead 377followed by an array of 378.Va struct file , 379whose size depends on the current number of such objects in the system. 380.It Li KERN_HOSTID 381Get or set the host id. 382.It Li KERN_HOSTNAME 383Get or set the hostname. 384.It Li KERN_JOB_CONTROL 385Return 1 if job control is available on this system, otherwise 0. 386.It Li KERN_MAXFILES 387The maximum number of files that may be open in the system. 388.It Li KERN_MAXFILESPERPROC 389The maximum number of files that may be open for a single process. 390This limit only applies to processes with an effective uid of nonzero 391at the time of the open request. 392Files that have already been opened are not affected if the limit 393or the effective uid is changed. 394.It Li KERN_MAXPROC 395The maximum number of concurrent processes the system will allow. 396.It Li KERN_MAXPROCPERUID 397The maximum number of concurrent processes the system will allow 398for a single effective uid. 399This limit only applies to processes with an effective uid of nonzero 400at the time of a fork request. 401Processes that have already been started are not affected if the limit 402is changed. 403.It Li KERN_MAXVNODES 404The maximum number of vnodes available on the system. 405.It Li KERN_NGROUPS 406The maximum number of supplemental groups. 407.It Li KERN_NISDOMAINNAME 408The name of the current YP/NIS domain. 409.It Li KERN_OSRELDATE 410The kernel release version in the format 411.Ar M Ns Ar mm Ns Ar R Ns Ar xx , 412where 413.Ar M 414is the major version, 415.Ar mm 416is the two digit minor version, 417.Ar R 418is 0 if release branch, otherwise 1, 419and 420.Ar xx 421is updated when the available APIs change. 422.Pp 423The userland release version is available from 424.In osreldate.h ; 425parse this file if you need to get the release version of 426the currently installed userland. 427.It Li KERN_OSRELEASE 428The system release string. 429.It Li KERN_OSREV 430The system revision string. 431.It Li KERN_OSTYPE 432The system type string. 433.It Li KERN_POSIX1 434The version of 435.St -p1003.1 436with which the system 437attempts to comply. 438.It Li KERN_PROC 439Return the entire process table, or a subset of it. 440An array of pairs of 441.Va struct proc 442followed by corresponding 443.Va struct eproc 444structures is returned, 445whose size depends on the current number of such objects in the system. 446The third and fourth level names are as follows: 447.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 448.It "Third level name Fourth level is:" 449.It "KERN_PROC_ALL None" 450.It "KERN_PROC_PID A process ID" 451.It "KERN_PROC_PGRP A process group" 452.It "KERN_PROC_TTY A tty device" 453.It "KERN_PROC_UID A user ID" 454.It "KERN_PROC_RUID A real user ID" 455.El 456.Pp 457If the third level name is KERN_PROC_ARGS then the command line argument 458array is returned in a flattened form, i.e., zero-terminated arguments 459follow each other. 460The total size of array is returned. 461It is also possible for a process to set its own process title this way. 462.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 463.It Sy "Third level name Fourth level is:" 464.It "KERN_PROC_ARGS A process ID" 465.El 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.Pp 546.Bl -tag -width 6n 547.It Li PF_ROUTE 548Return the entire routing table or a subset of it. 549The data is returned as a sequence of routing messages (see 550.Xr route 4 551for the header file, format and meaning). 552The length of each message is contained in the message header. 553.Pp 554The third level name is a protocol number, which is currently always 0. 555The fourth level name is an address family, which may be set to 0 to 556select all address families. 557The fifth and sixth level names are as follows: 558.Bl -column "Fifth level nameXXXXXX" "Sixth level is:XXX" -offset indent 559.It Sy "Fifth level name Sixth level is:" 560.It "NET_RT_FLAGS rtflags" 561.It "NET_RT_DUMP None" 562.It "NET_RT_IFLIST 0 or if_index" 563.It "NET_RT_IFMALIST 0 or if_index" 564.El 565.Pp 566The 567.Dv NET_RT_IFMALIST 568name returns information about multicast group memberships on all interfaces 569if 0 is specified, or for the interface specified by 570.Va if_index . 571.It Li PF_INET 572Get or set various global information about the IPv4 573(Internet Protocol version 4). 574The third level name is the protocol. 575The fourth level name is the variable name. 576The currently defined protocols and names are: 577.Bl -column ProtocolXX VariableXX TypeXX ChangeableXX 578.It Sy "Protocol Variable Type Changeable" 579.It "icmp bmcastecho integer yes" 580.It "icmp maskrepl integer yes" 581.It "ip forwarding integer yes" 582.It "ip redirect integer yes" 583.It "ip ttl integer yes" 584.It "udp checksum integer yes" 585.El 586.Pp 587The variables are as follows: 588.Bl -tag -width 6n 589.It Li icmp.bmcastecho 590Returns 1 if an ICMP echo request to a broadcast or multicast address is 591to be answered. 592.It Li icmp.maskrepl 593Returns 1 if ICMP network mask requests are to be answered. 594.It Li ip.forwarding 595Returns 1 when IP forwarding is enabled for the host, 596meaning that the host is acting as a router. 597.It Li ip.redirect 598Returns 1 when ICMP redirects may be sent by the host. 599This option is ignored unless the host is routing IP packets, 600and should normally be enabled on all systems. 601.It Li ip.ttl 602The maximum time-to-live (hop count) value for an IP packet sourced by 603the system. 604This value applies to normal transport protocols, not to ICMP. 605.It Li udp.checksum 606Returns 1 when UDP checksums are being computed and checked. 607Disabling UDP checksums is strongly discouraged. 608.Pp 609For variables net.inet.*.ipsec, please refer to 610.Xr ipsec 4 . 611.El 612.It Li PF_INET6 613Get or set various global information about the IPv6 614(Internet Protocol version 6). 615The third level name is the protocol. 616The fourth level name is the variable name. 617.Pp 618For variables net.inet6.* please refer to 619.Xr inet6 4 . 620For variables net.inet6.*.ipsec6, please refer to 621.Xr ipsec 4 . 622.El 623.Ss CTL_USER 624The string and integer information available for the CTL_USER level 625is detailed below. 626The changeable column shows whether a process with appropriate 627privilege may change the value. 628.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 629.It Sy "Second level name Type Changeable" 630.It "USER_BC_BASE_MAX integer no" 631.It "USER_BC_DIM_MAX integer no" 632.It "USER_BC_SCALE_MAX integer no" 633.It "USER_BC_STRING_MAX integer no" 634.It "USER_COLL_WEIGHTS_MAX integer no" 635.It "USER_CS_PATH string no" 636.It "USER_EXPR_NEST_MAX integer no" 637.It "USER_LINE_MAX integer no" 638.It "USER_POSIX2_CHAR_TERM integer no" 639.It "USER_POSIX2_C_BIND integer no" 640.It "USER_POSIX2_C_DEV integer no" 641.It "USER_POSIX2_FORT_DEV integer no" 642.It "USER_POSIX2_FORT_RUN integer no" 643.It "USER_POSIX2_LOCALEDEF integer no" 644.It "USER_POSIX2_SW_DEV integer no" 645.It "USER_POSIX2_UPE integer no" 646.It "USER_POSIX2_VERSION integer no" 647.It "USER_RE_DUP_MAX integer no" 648.It "USER_STREAM_MAX integer no" 649.It "USER_TZNAME_MAX integer no" 650.El 651.Bl -tag -width 6n 652.Pp 653.It Li USER_BC_BASE_MAX 654The maximum ibase/obase values in the 655.Xr bc 1 656utility. 657.It Li USER_BC_DIM_MAX 658The maximum array size in the 659.Xr bc 1 660utility. 661.It Li USER_BC_SCALE_MAX 662The maximum scale value in the 663.Xr bc 1 664utility. 665.It Li USER_BC_STRING_MAX 666The maximum string length in the 667.Xr bc 1 668utility. 669.It Li USER_COLL_WEIGHTS_MAX 670The maximum number of weights that can be assigned to any entry of 671the LC_COLLATE order keyword in the locale definition file. 672.It Li USER_CS_PATH 673Return a value for the 674.Ev PATH 675environment variable that finds all the standard utilities. 676.It Li USER_EXPR_NEST_MAX 677The maximum number of expressions that can be nested within 678parenthesis by the 679.Xr expr 1 680utility. 681.It Li USER_LINE_MAX 682The maximum length in bytes of a text-processing utility's input 683line. 684.It Li USER_POSIX2_CHAR_TERM 685Return 1 if the system supports at least one terminal type capable of 686all operations described in 687.St -p1003.2 , 688otherwise 0. 689.It Li USER_POSIX2_C_BIND 690Return 1 if the system's C-language development facilities support the 691C-Language Bindings Option, otherwise 0. 692.It Li USER_POSIX2_C_DEV 693Return 1 if the system supports the C-Language Development Utilities Option, 694otherwise 0. 695.It Li USER_POSIX2_FORT_DEV 696Return 1 if the system supports the FORTRAN Development Utilities Option, 697otherwise 0. 698.It Li USER_POSIX2_FORT_RUN 699Return 1 if the system supports the FORTRAN Runtime Utilities Option, 700otherwise 0. 701.It Li USER_POSIX2_LOCALEDEF 702Return 1 if the system supports the creation of locales, otherwise 0. 703.It Li USER_POSIX2_SW_DEV 704Return 1 if the system supports the Software Development Utilities Option, 705otherwise 0. 706.It Li USER_POSIX2_UPE 707Return 1 if the system supports the User Portability Utilities Option, 708otherwise 0. 709.It Li USER_POSIX2_VERSION 710The version of 711.St -p1003.2 712with which the system attempts to comply. 713.It Li USER_RE_DUP_MAX 714The maximum number of repeated occurrences of a regular expression 715permitted when using interval notation. 716.It Li USER_STREAM_MAX 717The minimum maximum number of streams that a process may have open 718at any one time. 719.It Li USER_TZNAME_MAX 720The minimum maximum number of types supported for the name of a 721timezone. 722.El 723.Ss CTL_VM 724The string and integer information available for the CTL_VM level 725is detailed below. 726The changeable column shows whether a process with appropriate 727privilege may change the value. 728.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 729.It Sy "Second level name Type Changeable" 730.It "VM_LOADAVG struct loadavg no" 731.It "VM_METER struct vmtotal no" 732.It "VM_PAGEOUT_ALGORITHM integer yes" 733.It "VM_SWAPPING_ENABLED integer maybe" 734.It "VM_V_CACHE_MAX integer yes" 735.It "VM_V_CACHE_MIN integer yes" 736.It "VM_V_FREE_MIN integer yes" 737.It "VM_V_FREE_RESERVED integer yes" 738.It "VM_V_FREE_TARGET integer yes" 739.It "VM_V_INACTIVE_TARGET integer yes" 740.It "VM_V_PAGEOUT_FREE_MIN integer yes" 741.El 742.Pp 743.Bl -tag -width 6n 744.It Li VM_LOADAVG 745Return the load average history. 746The returned data consists of a 747.Va struct loadavg . 748.It Li VM_METER 749Return the system wide virtual memory statistics. 750The returned data consists of a 751.Va struct vmtotal . 752.It Li VM_PAGEOUT_ALGORITHM 7530 if the statistics-based page management algorithm is in use 754or 1 if the near-LRU algorithm is in use. 755.It Li VM_SWAPPING_ENABLED 7561 if process swapping is enabled or 0 if disabled. 757This variable is 758permanently set to 0 if the kernel was built with swapping disabled. 759.It Li VM_V_CACHE_MAX 760Maximum desired size of the cache queue. 761.It Li VM_V_CACHE_MIN 762Minimum desired size of the cache queue. 763If the cache queue size 764falls very far below this value, the pageout daemon is awakened. 765.It Li VM_V_FREE_MIN 766Minimum amount of memory (cache memory plus free memory) 767required to be available before a process waiting on memory will be 768awakened. 769.It Li VM_V_FREE_RESERVED 770Processes will awaken the pageout daemon and wait for memory if the 771number of free and cached pages drops below this value. 772.It Li VM_V_FREE_TARGET 773The total amount of free memory (including cache memory) that the 774pageout daemon tries to maintain. 775.It Li VM_V_INACTIVE_TARGET 776The desired number of inactive pages that the pageout daemon should 777achieve when it runs. 778Inactive pages can be quickly inserted into 779process address space when needed. 780.It Li VM_V_PAGEOUT_FREE_MIN 781If the amount of free and cache memory falls below this value, the 782pageout daemon will enter "memory conserving mode" to avoid deadlock. 783.El 784.Sh RETURN VALUES 785.Rv -std 786.Sh ERRORS 787The following errors may be reported: 788.Bl -tag -width Er 789.It Bq Er EFAULT 790The buffer 791.Fa name , 792.Fa oldp , 793.Fa newp , 794or length pointer 795.Fa oldlenp 796contains an invalid address. 797.It Bq Er EINVAL 798The 799.Fa name 800array is less than two or greater than CTL_MAXNAME. 801.It Bq Er EINVAL 802A non-null 803.Fa newp 804is given and its specified length in 805.Fa newlen 806is too large or too small. 807.It Bq Er ENOMEM 808The length pointed to by 809.Fa oldlenp 810is too short to hold the requested value. 811.It Bq Er ENOMEM 812The smaller of either the length pointed to by 813.Fa oldlenp 814or the estimated size of the returned data exceeds the 815system limit on locked memory. 816.It Bq Er ENOMEM 817Locking the buffer 818.Fa oldp , 819or a portion of the buffer if the estimated size of the data 820to be returned is smaller, 821would cause the process to exceed its per-process locked memory limit. 822.It Bq Er ENOTDIR 823The 824.Fa name 825array specifies an intermediate rather than terminal name. 826.It Bq Er EISDIR 827The 828.Fa name 829array specifies a terminal name, but the actual name is not terminal. 830.It Bq Er ENOENT 831The 832.Fa name 833array specifies a value that is unknown. 834.It Bq Er EPERM 835An attempt is made to set a read-only value. 836.It Bq Er EPERM 837A process without appropriate privilege attempts to set a value. 838.El 839.Sh FILES 840.Bl -tag -width <netinet/icmpXvar.h> -compact 841.It In sys/sysctl.h 842definitions for top level identifiers, second level kernel and hardware 843identifiers, and user level identifiers 844.It In sys/socket.h 845definitions for second level network identifiers 846.It In sys/gmon.h 847definitions for third level profiling identifiers 848.It In vm/vm_param.h 849definitions for second level virtual memory identifiers 850.It In netinet/in.h 851definitions for third level IPv4/IPv6 identifiers and 852fourth level IPv4/v6 identifiers 853.It In netinet/icmp_var.h 854definitions for fourth level ICMP identifiers 855.It In netinet/icmp6.h 856definitions for fourth level ICMPv6 identifiers 857.It In netinet/udp_var.h 858definitions for fourth level UDP identifiers 859.El 860.Sh SEE ALSO 861.Xr sysconf 3 , 862.Xr sysctl 8 863.Sh HISTORY 864The 865.Fn sysctl 866function first appeared in 867.Bx 4.4 . 868