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.\" 4. 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.\" $FreeBSD$ 30.\" 31.Dd May 17, 2013 32.Dt SYSCTL 3 33.Os 34.Sh NAME 35.Nm sysctl , 36.Nm sysctlbyname , 37.Nm sysctlnametomib 38.Nd get or set system information 39.Sh LIBRARY 40.Lb libc 41.Sh SYNOPSIS 42.In sys/types.h 43.In sys/sysctl.h 44.Ft int 45.Fn sysctl "const int *name" "u_int namelen" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen" 46.Ft int 47.Fn sysctlbyname "const char *name" "void *oldp" "size_t *oldlenp" "const void *newp" "size_t newlen" 48.Ft int 49.Fn sysctlnametomib "const char *name" "int *mibp" "size_t *sizep" 50.Sh DESCRIPTION 51The 52.Fn sysctl 53function retrieves system information and allows processes with 54appropriate privileges to set system information. 55The information available from 56.Fn sysctl 57consists of integers, strings, and tables. 58Information may be retrieved and set from the command interface 59using the 60.Xr sysctl 8 61utility. 62.Pp 63Unless explicitly noted below, 64.Fn sysctl 65returns a consistent snapshot of the data requested. 66Consistency is obtained by locking the destination 67buffer into memory so that the data may be copied out without blocking. 68Calls to 69.Fn sysctl 70are serialized to avoid deadlock. 71.Pp 72The state is described using a ``Management Information Base'' (MIB) 73style name, listed in 74.Fa name , 75which is a 76.Fa namelen 77length array of integers. 78.Pp 79The 80.Fn sysctlbyname 81function accepts an ASCII representation of the name and internally 82looks up the integer name vector. 83Apart 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 the 110.Dv NULL 111argument for 112.Fa oldp . 113The size of the available data will be returned in the location pointed to by 114.Fa oldlenp . 115For some operations, the amount of space may change often. 116For these operations, 117the system attempts to round up so that the returned size is 118large enough for a call to return the data shortly thereafter. 119.Pp 120To set a new value, 121.Fa newp 122is set to point to a buffer of length 123.Fa newlen 124from which the requested value is to be taken. 125If a new value is not to be set, 126.Fa newp 127should be set to NULL and 128.Fa newlen 129set to 0. 130.Pp 131The 132.Fn sysctlnametomib 133function accepts an ASCII representation of the name, 134looks up the integer name vector, 135and returns the numeric representation in the mib array pointed to by 136.Fa mibp . 137The number of elements in the mib array is given by the location specified by 138.Fa sizep 139before the call, 140and that location gives the number of entries copied after a successful call. 141The resulting 142.Fa mib 143and 144.Fa size 145may be used in subsequent 146.Fn sysctl 147calls to get the data associated with the requested ASCII name. 148This interface is intended for use by applications that want to 149repeatedly request the same variable (the 150.Fn sysctl 151function runs in about a third the time as the same request made via the 152.Fn sysctlbyname 153function). 154The 155.Fn sysctlnametomib 156function is also useful for fetching mib prefixes and then adding 157a final component. 158For example, to fetch process information 159for processes with pid's less than 100: 160.Pp 161.Bd -literal -offset indent -compact 162int i, mib[4]; 163size_t len; 164struct kinfo_proc kp; 165 166/* Fill out the first three components of the mib */ 167len = 4; 168sysctlnametomib("kern.proc.pid", mib, &len); 169 170/* Fetch and print entries for pid's < 100 */ 171for (i = 0; i < 100; i++) { 172 mib[3] = i; 173 len = sizeof(kp); 174 if (sysctl(mib, 4, &kp, &len, NULL, 0) == -1) 175 perror("sysctl"); 176 else if (len > 0) 177 printkproc(&kp); 178} 179.Ed 180.Pp 181The top level names are defined with a CTL_ prefix in 182.In sys/sysctl.h , 183and are as follows. 184The next and subsequent levels down are found in the include files 185listed here, and described in separate sections below. 186.Bl -column CTLXMACHDEPXXX "Next level namesXXXXXX" -offset indent 187.It Sy "Name Next level names Description" 188.It "CTL_DEBUG sys/sysctl.h Debugging" 189.It "CTL_VFS sys/mount.h File system" 190.It "CTL_HW sys/sysctl.h Generic CPU, I/O" 191.It "CTL_KERN sys/sysctl.h High kernel limits" 192.It "CTL_MACHDEP sys/sysctl.h Machine dependent" 193.It "CTL_NET sys/socket.h Networking" 194.It "CTL_USER sys/sysctl.h User-level" 195.It "CTL_VM vm/vm_param.h Virtual memory" 196.El 197.Pp 198For example, the following retrieves the maximum number of processes allowed 199in the system: 200.Pp 201.Bd -literal -offset indent -compact 202int mib[2], maxproc; 203size_t len; 204 205mib[0] = CTL_KERN; 206mib[1] = KERN_MAXPROC; 207len = sizeof(maxproc); 208sysctl(mib, 2, &maxproc, &len, NULL, 0); 209.Ed 210.Pp 211To retrieve the standard search path for the system utilities: 212.Pp 213.Bd -literal -offset indent -compact 214int mib[2]; 215size_t len; 216char *p; 217 218mib[0] = CTL_USER; 219mib[1] = USER_CS_PATH; 220sysctl(mib, 2, NULL, &len, NULL, 0); 221p = malloc(len); 222sysctl(mib, 2, p, &len, NULL, 0); 223.Ed 224.Ss CTL_DEBUG 225The debugging variables vary from system to system. 226A debugging variable may be added or deleted without need to recompile 227.Fn sysctl 228to know about it. 229Each time it runs, 230.Fn sysctl 231gets the list of debugging variables from the kernel and 232displays their current values. 233The system defines twenty 234.Pq Vt "struct ctldebug" 235variables named 236.Va debug0 237through 238.Va debug19 . 239They are declared as separate variables so that they can be 240individually initialized at the location of their associated variable. 241The loader prevents multiple use of the same variable by issuing errors 242if a variable is initialized in more than one place. 243For example, to export the variable 244.Va dospecialcheck 245as a debugging variable, the following declaration would be used: 246.Pp 247.Bd -literal -offset indent -compact 248int dospecialcheck = 1; 249struct ctldebug debug5 = { "dospecialcheck", &dospecialcheck }; 250.Ed 251.Ss CTL_VFS 252A distinguished second level name, VFS_GENERIC, 253is used to get general information about all file systems. 254One of its third level identifiers is VFS_MAXTYPENUM 255that gives the highest valid file system type number. 256Its other third level identifier is VFS_CONF that 257returns configuration information about the file system 258type given as a fourth level identifier (see 259.Xr getvfsbyname 3 260as an example of its use). 261The remaining second level identifiers are the 262file system type number returned by a 263.Xr statfs 2 264call or from VFS_CONF. 265The third level identifiers available for each file system 266are given in the header file that defines the mount 267argument structure for that file system. 268.Ss CTL_HW 269The string and integer information available for the CTL_HW level 270is detailed below. 271The changeable column shows whether a process with appropriate 272privilege may change the value. 273.Bl -column "Second level nameXXXXXX" integerXXX -offset indent 274.It Sy "Second level name Type Changeable" 275.It "HW_MACHINE string no" 276.It "HW_MODEL string no" 277.It "HW_NCPU integer no" 278.It "HW_BYTEORDER integer no" 279.It "HW_PHYSMEM integer no" 280.It "HW_USERMEM integer no" 281.It "HW_PAGESIZE integer no" 282.\".It "HW_DISKNAMES integer no" 283.\".It "HW_DISKSTATS integer no" 284.It "HW_FLOATINGPT integer no" 285.It "HW_MACHINE_ARCH string no" 286.It "HW_REALMEM integer no" 287.El 288.Bl -tag -width 6n 289.It Li HW_MACHINE 290The machine class. 291.It Li HW_MODEL 292The machine model 293.It Li HW_NCPU 294The number of cpus. 295.It Li HW_BYTEORDER 296The byteorder (4,321, or 1,234). 297.It Li HW_PHYSMEM 298The bytes of physical memory. 299.It Li HW_USERMEM 300The bytes of non-kernel memory. 301.It Li HW_PAGESIZE 302The software page size. 303.\".It Fa HW_DISKNAMES 304.\".It Fa HW_DISKSTATS 305.It Li HW_FLOATINGPT 306Nonzero if the floating point support is in hardware. 307.It Li HW_MACHINE_ARCH 308The machine dependent architecture type. 309.It Li HW_REALMEM 310The bytes of real memory. 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 "KERNXMAXFILESPERPROCXXX" "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 xfile no" 328.It "KERN_HOSTID integer yes" 329.It "KERN_HOSTUUID string yes" 330.It "KERN_HOSTNAME string yes" 331.It "KERN_JOB_CONTROL integer no" 332.It "KERN_MAXFILES integer yes" 333.It "KERN_MAXFILESPERPROC 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 node not applicable" 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 xvnode no" 352.El 353.Bl -tag -width 6n 354.It Li KERN_ARGMAX 355The maximum bytes of argument to 356.Xr execve 2 . 357.It Li KERN_BOOTFILE 358The full pathname of the file from which the kernel was loaded. 359.It Li KERN_BOOTTIME 360A 361.Va struct timeval 362structure is returned. 363This structure contains the time that the system was booted. 364.It Li KERN_CLOCKRATE 365A 366.Va struct clockinfo 367structure is returned. 368This structure contains the clock, statistics clock and profiling clock 369frequencies, the number of micro-seconds per hz tick and the skew rate. 370.It Li KERN_FILE 371Return the entire file table. 372The returned data consists of an array of 373.Va struct xfile , 374whose size depends on the current number of such objects in the system. 375.It Li KERN_HOSTID 376Get or set the host ID. 377.It Li KERN_HOSTUUID 378Get or set the host's universally unique identifier (UUID). 379.It Li KERN_HOSTNAME 380Get or set the hostname. 381.It Li KERN_JOB_CONTROL 382Return 1 if job control is available on this system, otherwise 0. 383.It Li KERN_MAXFILES 384The maximum number of files that may be open in the system. 385.It Li KERN_MAXFILESPERPROC 386The maximum number of files that may be open for a single process. 387This limit only applies to processes with an effective uid of nonzero 388at the time of the open request. 389Files that have already been opened are not affected if the limit 390or the effective uid is changed. 391.It Li KERN_MAXPROC 392The maximum number of concurrent processes the system will allow. 393.It Li KERN_MAXPROCPERUID 394The maximum number of concurrent processes the system will allow 395for a single effective uid. 396This limit only applies to processes with an effective uid of nonzero 397at the time of a fork request. 398Processes that have already been started are not affected if the limit 399is changed. 400.It Li KERN_MAXVNODES 401The maximum number of vnodes available on the system. 402.It Li KERN_NGROUPS 403The maximum number of supplemental groups. 404.It Li KERN_NISDOMAINNAME 405The name of the current YP/NIS domain. 406.It Li KERN_OSRELDATE 407The kernel release version in the format 408.Ar M Ns Ar mm Ns Ar R Ns Ar xx , 409where 410.Ar M 411is the major version, 412.Ar mm 413is the two digit minor version, 414.Ar R 415is 0 if release branch, otherwise 1, 416and 417.Ar xx 418is updated when the available APIs change. 419.Pp 420The userland release version is available from 421.In osreldate.h ; 422parse this file if you need to get the release version of 423the currently installed userland. 424.It Li KERN_OSRELEASE 425The system release string. 426.It Li KERN_OSREV 427The system revision string. 428.It Li KERN_OSTYPE 429The system type string. 430.It Li KERN_POSIX1 431The version of 432.St -p1003.1 433with which the system 434attempts to comply. 435.It Li KERN_PROC 436Return selected information about specific running processes. 437.Pp 438For the following names, an array of 439.Va struct kinfo_proc 440structures is returned, 441whose size depends on the current number of such objects in the system. 442.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 443.It "Third level name Fourth level is:" 444.It "KERN_PROC_ALL None" 445.It "KERN_PROC_PID A process ID" 446.It "KERN_PROC_PGRP A process group" 447.It "KERN_PROC_TTY A tty device" 448.It "KERN_PROC_UID A user ID" 449.It "KERN_PROC_RUID A real user ID" 450.El 451.Pp 452If the third level name is 453.Dv KERN_PROC_ARGS 454then the command line argument 455array is returned in a flattened form, i.e., zero-terminated arguments 456follow each other. 457The total size of array is returned. 458It is also possible for a process to set its own process title this way. 459If the third level name is 460.Dv KERN_PROC_PATHNAME , 461the path of the 462process' text file is stored. 463For 464.Dv KERN_PROC_PATHNAME , 465a process ID of 466.Li \-1 467implies the current process. 468.Bl -column "Third level nameXXXXXX" "Fourth level is:XXXXXX" -offset indent 469.It Sy "Third level name Fourth level is:" 470.It Dv KERN_PROC_ARGS Ta "A process ID" 471.It Dv KERN_PROC_PATHNAME Ta "A process ID" 472.El 473.It Li KERN_PROF 474Return profiling information about the kernel. 475If the kernel is not compiled for profiling, 476attempts to retrieve any of the KERN_PROF values will 477fail with 478.Er ENOENT . 479The third level names for the string and integer profiling information 480is detailed below. 481The changeable column shows whether a process with appropriate 482privilege may change the value. 483.Bl -column "GPROFXGMONPARAMXXX" "struct gmonparamXXX" -offset indent 484.It Sy "Third level name Type Changeable" 485.It "GPROF_STATE integer yes" 486.It "GPROF_COUNT u_short[\|] yes" 487.It "GPROF_FROMS u_short[\|] yes" 488.It "GPROF_TOS struct tostruct yes" 489.It "GPROF_GMONPARAM struct gmonparam no" 490.El 491.Pp 492The variables are as follows: 493.Bl -tag -width 6n 494.It Li GPROF_STATE 495Returns GMON_PROF_ON or GMON_PROF_OFF to show that profiling 496is running or stopped. 497.It Li GPROF_COUNT 498Array of statistical program counter counts. 499.It Li GPROF_FROMS 500Array indexed by program counter of call-from points. 501.It Li GPROF_TOS 502Array of 503.Va struct tostruct 504describing destination of calls and their counts. 505.It Li GPROF_GMONPARAM 506Structure giving the sizes of the above arrays. 507.El 508.It Li KERN_QUANTUM 509The maximum period of time, in microseconds, for which a process is allowed 510to run without being preempted if other processes are in the run queue. 511.It Li KERN_SAVED_IDS 512Returns 1 if saved set-group and saved set-user ID is available. 513.It Li KERN_SECURELVL 514The system security level. 515This level may be raised by processes with appropriate privilege. 516It may not be lowered. 517.It Li KERN_VERSION 518The system version string. 519.It Li KERN_VNODE 520Return the entire vnode table. 521Note, the vnode table is not necessarily a consistent snapshot of 522the system. 523The returned data consists of an array whose size depends on the 524current number of such objects in the system. 525Each element of the array consists of a 526.Va struct xvnode . 527.El 528.Ss CTL_NET 529The string and integer information available for the CTL_NET level 530is detailed below. 531The changeable column shows whether a process with appropriate 532privilege may change the value. 533.Bl -column "Second level nameXXXXXX" "routing messagesXXX" -offset indent 534.It Sy "Second level name Type Changeable" 535.It "PF_ROUTE routing messages no" 536.It "PF_INET IPv4 values yes" 537.It "PF_INET6 IPv6 values yes" 538.El 539.Bl -tag -width 6n 540.It Li PF_ROUTE 541Return the entire routing table or a subset of it. 542The data is returned as a sequence of routing messages (see 543.Xr route 4 544for the header file, format and meaning). 545The length of each message is contained in the message header. 546.Pp 547The third level name is a protocol number, which is currently always 0. 548The fourth level name is an address family, which may be set to 0 to 549select all address families. 550The fifth, sixth, and seventh level names are as follows: 551.Bl -column -offset indent "Fifth level Sixth level" "Seventh level" 552.It Sy "Fifth level Sixth level" Ta Sy "Seventh level" 553.It "NET_RT_FLAGS rtflags" Ta "None" 554.It "NET_RT_DUMP None" Ta "None or fib number" 555.It "NET_RT_IFLIST 0 or if_index" Ta None 556.It "NET_RT_IFMALIST 0 or if_index" Ta None 557.It "NET_RT_IFLISTL 0 or if_index" Ta None 558.El 559.Pp 560The 561.Dv NET_RT_IFMALIST 562name returns information about multicast group memberships on all interfaces 563if 0 is specified, or for the interface specified by 564.Va if_index . 565.Pp 566The 567.Dv NET_RT_IFLISTL 568is like 569.Dv NET_RT_IFLIST , 570just returning message header structs with additional fields allowing the 571interface to be extended without breaking binary compatibility. 572The 573.Dv NET_RT_IFLISTL 574uses 'l' versions of the message header structures: 575.Va struct if_msghdrl 576and 577.Va struct ifa_msghdrl . 578.It Li PF_INET 579Get or set various global information about the IPv4 580(Internet Protocol version 4). 581The third level name is the protocol. 582The fourth level name is the variable name. 583The currently defined protocols and names are: 584.Bl -column ProtocolXX VariableXX TypeXX ChangeableXX 585.It Sy "Protocol Variable Type Changeable" 586.It "icmp bmcastecho integer yes" 587.It "icmp maskrepl integer yes" 588.It "ip forwarding integer yes" 589.It "ip redirect integer yes" 590.It "ip ttl integer yes" 591.It "udp checksum integer yes" 592.El 593.Pp 594The variables are as follows: 595.Bl -tag -width 6n 596.It Li icmp.bmcastecho 597Returns 1 if an ICMP echo request to a broadcast or multicast address is 598to be answered. 599.It Li icmp.maskrepl 600Returns 1 if ICMP network mask requests are to be answered. 601.It Li ip.forwarding 602Returns 1 when IP forwarding is enabled for the host, 603meaning that the host is acting as a router. 604.It Li ip.redirect 605Returns 1 when ICMP redirects may be sent by the host. 606This option is ignored unless the host is routing IP packets, 607and should normally be enabled on all systems. 608.It Li ip.ttl 609The maximum time-to-live (hop count) value for an IP packet sourced by 610the system. 611This value applies to normal transport protocols, not to ICMP. 612.It Li udp.checksum 613Returns 1 when UDP checksums are being computed and checked. 614Disabling UDP checksums is strongly discouraged. 615.Pp 616For variables net.inet.*.ipsec, please refer to 617.Xr ipsec 4 . 618.El 619.It Li PF_INET6 620Get or set various global information about the IPv6 621(Internet Protocol version 6). 622The third level name is the protocol. 623The fourth level name is the variable name. 624.Pp 625For variables net.inet6.* please refer to 626.Xr inet6 4 . 627For variables net.inet6.*.ipsec6, please refer to 628.Xr ipsec 4 . 629.El 630.Ss CTL_USER 631The string and integer information available for the CTL_USER level 632is detailed below. 633The changeable column shows whether a process with appropriate 634privilege may change the value. 635.Bl -column "USER_COLL_WEIGHTS_MAXXXX" "integerXXX" -offset indent 636.It Sy "Second level name Type Changeable" 637.It "USER_BC_BASE_MAX integer no" 638.It "USER_BC_DIM_MAX integer no" 639.It "USER_BC_SCALE_MAX integer no" 640.It "USER_BC_STRING_MAX integer no" 641.It "USER_COLL_WEIGHTS_MAX integer no" 642.It "USER_CS_PATH string no" 643.It "USER_EXPR_NEST_MAX integer no" 644.It "USER_LINE_MAX integer no" 645.It "USER_POSIX2_CHAR_TERM integer no" 646.It "USER_POSIX2_C_BIND integer no" 647.It "USER_POSIX2_C_DEV integer no" 648.It "USER_POSIX2_FORT_DEV integer no" 649.It "USER_POSIX2_FORT_RUN integer no" 650.It "USER_POSIX2_LOCALEDEF integer no" 651.It "USER_POSIX2_SW_DEV integer no" 652.It "USER_POSIX2_UPE integer no" 653.It "USER_POSIX2_VERSION integer no" 654.It "USER_RE_DUP_MAX integer no" 655.It "USER_STREAM_MAX integer no" 656.It "USER_TZNAME_MAX integer no" 657.El 658.Bl -tag -width 6n 659.It Li USER_BC_BASE_MAX 660The maximum ibase/obase values in the 661.Xr bc 1 662utility. 663.It Li USER_BC_DIM_MAX 664The maximum array size in the 665.Xr bc 1 666utility. 667.It Li USER_BC_SCALE_MAX 668The maximum scale value in the 669.Xr bc 1 670utility. 671.It Li USER_BC_STRING_MAX 672The maximum string length in the 673.Xr bc 1 674utility. 675.It Li USER_COLL_WEIGHTS_MAX 676The maximum number of weights that can be assigned to any entry of 677the LC_COLLATE order keyword in the locale definition file. 678.It Li USER_CS_PATH 679Return a value for the 680.Ev PATH 681environment variable that finds all the standard utilities. 682.It Li USER_EXPR_NEST_MAX 683The maximum number of expressions that can be nested within 684parenthesis by the 685.Xr expr 1 686utility. 687.It Li USER_LINE_MAX 688The maximum length in bytes of a text-processing utility's input 689line. 690.It Li USER_POSIX2_CHAR_TERM 691Return 1 if the system supports at least one terminal type capable of 692all operations described in 693.St -p1003.2 , 694otherwise 0. 695.It Li USER_POSIX2_C_BIND 696Return 1 if the system's C-language development facilities support the 697C-Language Bindings Option, otherwise 0. 698.It Li USER_POSIX2_C_DEV 699Return 1 if the system supports the C-Language Development Utilities Option, 700otherwise 0. 701.It Li USER_POSIX2_FORT_DEV 702Return 1 if the system supports the FORTRAN Development Utilities Option, 703otherwise 0. 704.It Li USER_POSIX2_FORT_RUN 705Return 1 if the system supports the FORTRAN Runtime Utilities Option, 706otherwise 0. 707.It Li USER_POSIX2_LOCALEDEF 708Return 1 if the system supports the creation of locales, otherwise 0. 709.It Li USER_POSIX2_SW_DEV 710Return 1 if the system supports the Software Development Utilities Option, 711otherwise 0. 712.It Li USER_POSIX2_UPE 713Return 1 if the system supports the User Portability Utilities Option, 714otherwise 0. 715.It Li USER_POSIX2_VERSION 716The version of 717.St -p1003.2 718with which the system attempts to comply. 719.It Li USER_RE_DUP_MAX 720The maximum number of repeated occurrences of a regular expression 721permitted when using interval notation. 722.It Li USER_STREAM_MAX 723The minimum maximum number of streams that a process may have open 724at any one time. 725.It Li USER_TZNAME_MAX 726The minimum maximum number of types supported for the name of a 727timezone. 728.El 729.Ss CTL_VM 730The string and integer information available for the CTL_VM level 731is detailed below. 732The changeable column shows whether a process with appropriate 733privilege may change the value. 734.Bl -column "Second level nameXXXXXX" "struct loadavgXXX" -offset indent 735.It Sy "Second level name Type Changeable" 736.It "VM_LOADAVG struct loadavg no" 737.It "VM_TOTAL struct vmtotal no" 738.It "VM_SWAPPING_ENABLED integer maybe" 739.It "VM_V_CACHE_MAX integer yes" 740.It "VM_V_CACHE_MIN integer yes" 741.It "VM_V_FREE_MIN integer yes" 742.It "VM_V_FREE_RESERVED integer yes" 743.It "VM_V_FREE_TARGET integer yes" 744.It "VM_V_INACTIVE_TARGET integer yes" 745.It "VM_V_PAGEOUT_FREE_MIN integer yes" 746.El 747.Bl -tag -width 6n 748.It Li VM_LOADAVG 749Return the load average history. 750The returned data consists of a 751.Va struct loadavg . 752.It Li VM_TOTAL 753Return the system wide virtual memory statistics. 754The returned data consists of a 755.Va struct vmtotal . 756.It Li VM_SWAPPING_ENABLED 7571 if process swapping is enabled or 0 if disabled. 758This variable is 759permanently set to 0 if the kernel was built with swapping disabled. 760.It Li VM_V_CACHE_MAX 761Maximum desired size of the cache queue. 762.It Li VM_V_CACHE_MIN 763Minimum desired size of the cache queue. 764If the cache queue size 765falls very far below this value, the pageout daemon is awakened. 766.It Li VM_V_FREE_MIN 767Minimum amount of memory (cache memory plus free memory) 768required to be available before a process waiting on memory will be 769awakened. 770.It Li VM_V_FREE_RESERVED 771Processes will awaken the pageout daemon and wait for memory if the 772number of free and cached pages drops below this value. 773.It Li VM_V_FREE_TARGET 774The total amount of free memory (including cache memory) that the 775pageout daemon tries to maintain. 776.It Li VM_V_INACTIVE_TARGET 777The desired number of inactive pages that the pageout daemon should 778achieve when it runs. 779Inactive pages can be quickly inserted into 780process address space when needed. 781.It Li VM_V_PAGEOUT_FREE_MIN 782If the amount of free and cache memory falls below this value, the 783pageout daemon will enter "memory conserving mode" to avoid deadlock. 784.El 785.Sh RETURN VALUES 786.Rv -std 787.Sh FILES 788.Bl -tag -width <netinet/icmpXvar.h> -compact 789.It In sys/sysctl.h 790definitions for top level identifiers, second level kernel and hardware 791identifiers, and user level identifiers 792.It In sys/socket.h 793definitions for second level network identifiers 794.It In sys/gmon.h 795definitions for third level profiling identifiers 796.It In vm/vm_param.h 797definitions for second level virtual memory identifiers 798.It In netinet/in.h 799definitions for third level IPv4/IPv6 identifiers and 800fourth level IPv4/v6 identifiers 801.It In netinet/icmp_var.h 802definitions for fourth level ICMP identifiers 803.It In netinet/icmp6.h 804definitions for fourth level ICMPv6 identifiers 805.It In netinet/udp_var.h 806definitions for fourth level UDP identifiers 807.El 808.Sh ERRORS 809The following errors may be reported: 810.Bl -tag -width Er 811.It Bq Er EFAULT 812The buffer 813.Fa name , 814.Fa oldp , 815.Fa newp , 816or length pointer 817.Fa oldlenp 818contains an invalid address. 819.It Bq Er EINVAL 820The 821.Fa name 822array is less than two or greater than CTL_MAXNAME. 823.It Bq Er EINVAL 824A non-null 825.Fa newp 826is given and its specified length in 827.Fa newlen 828is too large or too small. 829.It Bq Er ENOMEM 830The length pointed to by 831.Fa oldlenp 832is too short to hold the requested value. 833.It Bq Er ENOMEM 834The smaller of either the length pointed to by 835.Fa oldlenp 836or the estimated size of the returned data exceeds the 837system limit on locked memory. 838.It Bq Er ENOMEM 839Locking the buffer 840.Fa oldp , 841or a portion of the buffer if the estimated size of the data 842to be returned is smaller, 843would cause the process to exceed its per-process locked memory limit. 844.It Bq Er ENOTDIR 845The 846.Fa name 847array specifies an intermediate rather than terminal name. 848.It Bq Er EISDIR 849The 850.Fa name 851array specifies a terminal name, but the actual name is not terminal. 852.It Bq Er ENOENT 853The 854.Fa name 855array specifies a value that is unknown. 856.It Bq Er EPERM 857An attempt is made to set a read-only value. 858.It Bq Er EPERM 859A process without appropriate privilege attempts to set a value. 860.El 861.Sh SEE ALSO 862.Xr confstr 3 , 863.Xr kvm 3 , 864.Xr sysconf 3 , 865.Xr sysctl 8 866.Sh HISTORY 867The 868.Fn sysctl 869function first appeared in 870.Bx 4.4 . 871