2 .\" The Regents of the University of California. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this list of conditions and the following disclaimer.
9 .\" 2. Redistributions in binary form must reproduce the above copyright
10 .\" notice, this list of conditions and the following disclaimer in the
11 .\" documentation and/or other materials provided with the distribution.
12 .\" 3. Neither the name of the University nor the names of its contributors
13 .\" may be used to endorse or promote products derived from this software
14 .\" without specific prior written permission.
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
28 .\" @(#)sysconf.3 8.3 (Berkeley) 4/19/94
35 .Nd get configurable system variables
41 .Fn sysconf "int name"
43 This interface is defined by
45 A far more complete interface is available using
50 function provides a method for applications to determine the current
51 value of a configurable system limit or option variable.
54 argument specifies the system variable to be queried.
55 Symbolic constants for each name value are found in the include file
57 Shell programmers who need access to these parameters should use the
61 The available values are as follows:
64 The maximum bytes of argument to
67 The maximum number of simultaneous processes per user id.
69 The frequency of the statistics clock in ticks per second.
71 The maximum number of elements in the I/O vector used by
77 .It Li _SC_NGROUPS_MAX
78 The maximum number of supplemental groups.
79 .It Li _SC_NPROCESSORS_CONF
80 The number of processors configured.
81 .It Li _SC_NPROCESSORS_ONLN
82 The number of processors currently online.
84 One more than the maximum value the system may assign to a new file descriptor.
86 The size of a system page in bytes.
91 The minimum maximum number of streams that a process may have open
94 The minimum maximum number of types supported for the name of a
96 .It Li _SC_JOB_CONTROL
97 Return 1 if job control is available on this system, otherwise \-1.
99 Returns 1 if saved set-group and saved set-user ID is available,
104 with which the system
106 .It Li _SC_BC_BASE_MAX
107 The maximum ibase/obase values in the
110 .It Li _SC_BC_DIM_MAX
111 The maximum array size in the
114 .It Li _SC_BC_SCALE_MAX
115 The maximum scale value in the
118 .It Li _SC_BC_STRING_MAX
119 The maximum string length in the
122 .It Li _SC_COLL_WEIGHTS_MAX
123 The maximum number of weights that can be assigned to any entry of
124 the LC_COLLATE order keyword in the locale definition file.
125 .It Li _SC_EXPR_NEST_MAX
126 The maximum number of expressions that can be nested within
131 The maximum length in bytes of a text-processing utility's input
133 .It Li _SC_RE_DUP_MAX
134 The maximum number of repeated occurrences of a regular expression
135 permitted when using interval notation.
139 with which the system attempts to comply.
141 Return 1 if the system's C-language development facilities support the
142 C-Language Bindings Option, otherwise \-1.
144 Return 1 if the system supports the C-Language Development Utilities Option,
146 .It Li _SC_2_CHAR_TERM
147 Return 1 if the system supports at least one terminal type capable of
148 all operations described in
151 .It Li _SC_2_FORT_DEV
152 Return 1 if the system supports the FORTRAN Development Utilities Option,
154 .It Li _SC_2_FORT_RUN
155 Return 1 if the system supports the FORTRAN Runtime Utilities Option,
157 .It Li _SC_2_LOCALEDEF
158 Return 1 if the system supports the creation of locales, otherwise \-1.
160 Return 1 if the system supports the Software Development Utilities Option,
163 Return 1 if the system supports the User Portability Utilities Option,
165 .It Li _SC_AIO_LISTIO_MAX
166 Maximum number of I/O operations in a single list I/O call supported.
168 Maximum number of outstanding asynchronous I/O operations supported.
169 .It Li _SC_AIO_PRIO_DELTA_MAX
170 The maximum amount by which a process can decrease its asynchronous I/O
171 priority level from its own scheduling priority.
172 .It Li _SC_DELAYTIMER_MAX
173 Maximum number of timer expiration overruns.
174 .It Li _SC_MQ_OPEN_MAX
175 The maximum number of open message queue descriptors a process may hold.
177 Maximum number of realtime signals reserved for application use.
178 .It Li _SC_SEM_NSEMS_MAX
179 Maximum number of semaphores that a process may have.
180 .It Li _SC_SEM_VALUE_MAX
181 The maximum value a semaphore may have.
182 .It Li _SC_SIGQUEUE_MAX
183 Maximum number of queued signals that a process may send and have pending at
184 the receiver(s) at any time.
186 Maximum number of timers per process supported.
187 .It Li _SC_GETGR_R_SIZE_MAX
188 Suggested initial value for the size of the group entry buffer.
189 .It Li _SC_GETPW_R_SIZE_MAX
190 Suggested initial value for the size of the password entry buffer.
191 .It Li _SC_HOST_NAME_MAX
192 Maximum length of a host name (not including the terminating null) as
196 .It Li _SC_LOGIN_NAME_MAX
197 Maximum length of a login name.
198 .It Li _SC_THREAD_STACK_MIN
199 Minimum size in bytes of thread stack storage.
200 .It Li _SC_THREAD_THREADS_MAX
201 Maximum number of threads that can be created per process.
202 .It Li _SC_TTY_NAME_MAX
203 Maximum length of terminal device name.
204 .It Li _SC_SYMLOOP_MAX
205 Maximum number of symbolic links that can be reliably traversed in the
206 resolution of a pathname in the absence of a loop.
207 .It Li _SC_ATEXIT_MAX
208 Maximum number of functions that may be registered with
210 .It Li _SC_XOPEN_VERSION
211 An integer value greater than or equal to 4,
212 indicating the version of the X/Open Portability Guide to which this
214 .It Li _SC_XOPEN_XCU_VERSION
215 An integer value indicating the version of the XCU Specification to which
216 this system conforms.
219 These values also exist, but may not be standard:
221 .It Li _SC_CPUSET_SIZE
222 Size of the kernel cpuset.
223 .It Li _SC_PHYS_PAGES
224 The number of pages of physical memory.
225 Note that it is possible that the product of this value and the value of
229 in some configurations on a 32bit machine.
234 is not successful, \-1 is returned and
236 is set appropriately.
237 Otherwise, if the variable is associated with functionality that is not
238 supported, \-1 is returned and
241 Otherwise, the current variable value is returned.
245 function may fail and set
247 for any of the errors specified for the library function
249 In addition, the following error may be reported:
262 Except for the fact that values returned by
264 may change over the lifetime of the calling process,
265 this function conforms to
270 function first appeared in
273 The value for _SC_STREAM_MAX is a minimum maximum, and required to be
274 the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously
275 small and misleading number.