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46 .\" Copyright (c) 2013 Gary Mills
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48 .TH SYSCONF 3C "Apr 16, 2013"
49 .SH NAME
50 sysconf \- get configurable system variables
51 .SH SYNOPSIS
52 .LP
53 .nf
54 #include <unistd.h>
56 \fBlong\fR \fBsysconf\fR(\fBint\fR \fIname\fR);
57 .fi
59 .SH DESCRIPTION
60 .sp
61 .LP
62 The \fBsysconf()\fR function provides a method for an application to determine
63 the current value of a configurable system limit or option (variable).
64 .sp
65 .LP
66 The \fIname\fR argument represents the system variable to be queried. The
67 following table lists the minimal set of system variables from \fB<limits.h>\fR
68 and \fB<unistd.h>\fR that can be returned by \fBsysconf()\fR and the symbolic
69 constants defined in \fB<unistd.h>\fR that are the corresponding values used
70 for \fIname\fR on the SPARC and x86 platforms.
71 .sp
72 .in +2
73 .nf
74 Name Return Value Meaning
75 _______________________________________________________________________
76 _SC_2_C_BIND _POSIX2_C_BIND Supports the C lang-
77 uage binding option
78 _SC_2_C_DEV _POSIX2_C_DEV Supports the C lang-
79 uage development
80 utilities option
81 _SC_2_C_VERSION _POSIX2_C_VERSION Integer value
82 indicates version
83 of ISO POSIX-2
84 standard (Commands)
85 _SC_2_CHAR_TERM _POSIX2_CHAR_TERM Supports at least
86 one terminal
87 _SC_2_FORT_DEV _POSIX2_FORT_DEV Supports FORTRAN
88 Development
89 Utilities Option
90 _SC_2_FORT_RUN _POSIX2_FORT_RUN Supports FORTRAN
91 Run-time Utilities
92 Option
93 _SC_2_LOCALEDEF _POSIX2_LOCALEDEF Supports creation
94 of locales by the
95 localedef utility
96 _SC_2_SW_DEV _POSIX2_SW_DEV Supports Software
97 Development Utility
98 Option
99 _SC_2_UPE _POSIX2_UPE Supports User
100 Portability
101 Utilities Option
102 _SC_2_VERSION _POSIX2_VERSION Integer value
103 indicates version
104 of ISO POSIX-2
105 standard (C language
106 binding)
107 _SC_AIO_LISTIO_MAX AIO_LISTIO_MAX Max number of I/O
108 operations in a
109 single list I/O call
110 supported
111 _SC_AIO_MAX AIO_MAX Max number of
112 outstanding
113 asynchronous I/O
114 operations supported
115 _SC_AIO_PRIO_DELTA_MAX AIO_PRIO_DELTA_MAX Max amount by which
116 process can decrease
117 its asynchronous
118 I/O priority level
119 from its own
120 scheduling priority
121 _SC_ARG_MAX ARG_MAX Max size of argv[]
122 plus envp[]
123 _SC_ASYNCHRONOUS_IO _POSIX_ASYNCHRONOUS_IO Supports
124 Asynchronous I/O
125 _SC_ATEXIT_MAX ATEXIT_MAX Max number of
126 functions that can
127 be registered with
128 atexit()
129 _SC_AVPHYS_PAGES Number of physical
130 memory pages not
131 currently in use by
132 system
133 _SC_BARRIERS _POSIX_BARRIERS Supports Barriers
134 option
135 _SC_BC_BASE_MAX BC_BASE_MAX Maximum obase values
136 allowed by bc
137 _SC_BC_DIM_MAX BC_DIM_MAX Max number of
138 elements permitted
139 in array by bc
140 _SC_BC_SCALE_MAX BC_SCALE_MAX Max scale value
141 allowed by bc
142 _SC_BC_STRING_MAX BC_STRING_MAX Max length of string
143 constant allowed by
144 bc
145 _SC_CHILD_MAX CHILD_MAX Max processes
146 allowed to a UID
147 _SC_CLK_TCK CLK_TCK Ticks per second
148 (clock_t)
149 _SC_CLOCK_SELECTION _POSIX_CLOCK_SELECTION Supports Clock
150 Selection option
151 _SC_COLL_WEIGHTS_MAX COLL_WEIGHTS_MAX Max number of
152 weights that can be
153 assigned to entry of
154 the LC_COLLATE order
155 keyword in locale
156 definition file
157 _SC_CPUID_MAX Max possible
158 processor ID
159 _SC_DELAYTIMER_MAX DELAYTIMER_MAX Max number of timer
160 expiration overruns
161 _SC_EXPR_NEST_MAX EXPR_NEST_MAX Max number of
162 parentheses by expr
163 _SC_FSYNC _POSIX_FSYNC Supports File
164 Synchronization
165 _SC_GETGR_R_SIZE_MAX Max size of group
166 entry buffer
167 _SC_GETPW_R_SIZE_MAX Max size of password
168 entry buffer
169 _SC_HOST_NAME_MAX _POSIX_HOST_NAME_MAX Maximum length of a
170 host name (excluding
171 terminating null)
172 _SC_IOV_MAX IOV_MAX Max number of iovec
173 structures available
174 to one process for
175 use with readv()
176 and writev()
177 _SC_JOB_CONTROL _POSIX_JOB_CONTROL Job control
178 supported?
179 _SC_LINE_MAX LINE_MAX Max length of input
180 line
181 _SC_LOGIN_NAME_MAX LOGIN_NAME_MAX Max length of login
182 name
183 _SC_LOGNAME_MAX LOGNAME_MAX
184 _SC_MAPPED_FILES _POSIX_MAPPED_FILES Supports Memory
185 Mapped Files
186 _SC_MAXPID Max pid value
187 _SC_MEMLOCK _POSIX_MEMLOCK Supports Process
188 Memory Locking
189 _SC_MEMLOCK_RANGE _POSIX_MEMLOCK_RANGE Supports Range
190 Memory Locking
191 _SC_MEMORY_PROTECTION _POSIX_MEMORY_PROTECTION Supports Memory
192 Protection
193 _SC_MESSAGE_PASSING _POSIX_MESSAGE_PASSING Supports Message
194 Passing
195 _SC_MONOTONIC_CLOCK _POSIX_MONOTONIC_CLOCK Supports Monotonic
196 Clock option
197 _SC_MQ_OPEN_MAX MQ_OPEN_MAX Max number of open
198 message queues a
199 process can hold
200 _SC_MQ_PRIO_MAX MQ_PRIO_MAX Max number of
201 message priorities
202 supported
203 _SC_NGROUPS_MAX NGROUPS_MAX Max simultaneous
204 groups to which
205 one can belong
206 _SC_NPROCESSORS_CONF Number of processors
207 configured
208 _SC_NPROCESSORS_MAX Max number of
209 processors supported
210 by platform
211 _SC_NPROCESSORS_ONLN Number of processors
212 online
213 _SC_OPEN_MAX OPEN_MAX Max open files per
214 process
215 _SC_PAGESIZE PAGESIZE System memory page
216 size
217 _SC_PAGE_SIZE PAGESIZE Same as _SC_PAGESIZE
218 _SC_PASS_MAX PASS_MAX Max number of
219 significant bytes
220 in a password
221 _SC_PHYS_PAGES Total number of
222 pages of physical
223 memory in system
224 _SC_PRIORITIZED_IO _POSIX_PRIORITIZED_IO Supports Prioritized
225 I/O
226 _SC_PRIORITY_SCHEDULING _POSIX_PRIORITY_SCHEDULING Supports Process
227 Scheduling
228 _SC_RAW_SOCKETS _POSIX_RAW_SOCKETS Supports Raw Sockets
229 option
230 _SC_RE_DUP_MAX RE_DUP_MAX Max number of
231 repeated occurrences
232 of a regular
233 expression permitted
234 when using interval
235 notation \e{m,n\e}
236 _SC_READER_WRITER_LOCKS _POSIX_READER_WRITER_LOCKS Supports IPV6 option
237 _SC_REALTIME_SIGNALS _POSIX_REALTIME_SIGNALS Supports Realtime
238 Signals
239 _SC_REGEXP _POSIX_REGEXP Supports Regular
240 Expression Handling
241 option
242 _SC_RTSIG_MAX RTSIG_MAX Max number of
243 realtime signals
244 reserved for
245 application use
246 _SC_SAVED_IDS _POSIX_SAVED_IDS Saved IDs
247 (seteuid())
248 supported?
249 _SC_SEM_NSEMS_MAX SEM_NSEMS_MAX Max number of POSIX
250 semaphores a process
251 can have
252 _SC_SEM_VALUE_MAX SEM_VALUE_MAX Max value a POSIX
253 semaphore can have
254 _SC_SEMAPHORES _POSIX_SEMAPHORES Supports Semaphores
255 _SC_SHARED_MEMORY_ _POSIX_SHARED_MEMORY_ Supports Shared
256 OBJECTS OBJECTS Memory Objects
257 _SC_SHELL _POSIX_SHELL Supports POSIX shell
258 _SC_SIGQUEUE_MAX SIGQUEUE_MAX Max number of queued
259 signals that a
260 process can send and
261 have pending at
262 receiver(s) at a
263 time
264 _SC_SPAWN _POSIX_SPAWN Supports Spawn option
265 _SC_SPIN_LOCKS _POSIX_SPIN_LOCKS Supports Spin Locks
266 option
267 _SC_STACK_PROT Default stack
268 protection
269 _SC_STREAM_MAX STREAM_MAX Number of streams
270 one process can
271 have open at a time
272 _SC_SYMLOOP_MAX _POSIX_SYMLOOP_MAX Max number of symbolic
273 links that can be
274 reliably traversed in
275 the resolution of a
276 pathname in the absence
277 of a loop
278 _SC_SYNCHRONIZED_IO _POSIX_SYNCHRONIZED_IO Supports
279 Synchronized I/O
280 _SC_THREAD_ATTR_ _POSIX_THREAD_ATTR_ Supports Thread
281 STACKADDR STACKADDR Stack Address
282 Attribute option
283 _SC_THREAD_ATTR_ _POSIX_THREAD_ATTR_ Supports Thread
284 STACKSIZE STACKSIZE Stack Size
285 Attribute option
286 _SC_THREAD_DESTRUCTOR_ PTHREAD_DESTRUCTOR_ Number attempts made
287 ITERATIONS ITERATIONS to destroy thread-
288 specific data on
289 thread exit
290 _SC_THREAD_KEYS_MAX PTHREAD_KEYS_MAX Max number of data
291 keys per process
292 _SC_THREAD_PRIO_ _POSIX_THREAD_PRIO_ Supports Priority
293 INHERIT INHERIT Inheritance option
294 _SC_THREAD_PRIO_ _POSIX_THREAD_PRIO_ Supports Priority
295 PROTECT PROTECT Protection option
296 _SC_THREAD_PRIORITY_ _POSIX_THREAD_PRIORITY_ Supports Thread
297 SCHEDULING SCHEDULING Execution
298 Scheduling option
299 _SC_THREAD_PROCESS_ _POSIX_THREAD_PROCESS_ Supports
300 SHARED SHARED Process-Shared
301 Synchronization
302 option
303 _SC_THREAD_SAFE_ _POSIX_THREAD_SAFE_ Supports Thread-Safe
304 FUNCTIONS FUNCTIONS Functions option
305 _SC_THREAD_STACK_MIN PTHREAD_STACK_MIN Min byte size of
306 thread stack storage
307 _SC_THREAD_THREADS_MAX PTHREAD_THREADS_MAX Max number of
308 threads per process
309 _SC_THREADS _POSIX_THREADS Supports Threads
310 option
311 _SC_TIMEOUTS _POSIX_TIMEOUTS Supports Timeouts
312 option
313 _SC_TIMER_MAX TIMER_MAX Max number of timer
314 per process
315 supported
316 _SC_TIMERS _POSIX_TIMERS Supports Timers
317 _SC_TTY_NAME_MAX TTYNAME_MAX Max length of tty
318 device name
319 _SC_TZNAME_MAX TZNAME_MAX Max number of bytes
320 supported for name
321 of a time zone
322 _SC_V6_ILP32_OFF32 _POSIX_V6_ILP32_OFF32 Supports X/Open
323 ILP32 w/32-bit
324 offset build
325 environment
326 _SC_V6_ILP32_OFFBIG _POSIX_V6_ILP32_OFFBIG Supports X/Open
327 ILP32 w/64-bit
328 offset build
329 environment
330 _SC_V6_LP64_OFF64 _POSIX_V6_LP64_OFF64 Supports X/Open
331 LP64 w/64-bit
332 offset build
333 environment
334 _SC_V6_LPBIG_OFFBIG _POSIX_V6_LPBIG_OFFBIG Same as
335 _SC_V6_LP64_OFF64
336 _SC_VERSION _POSIX_VERSION POSIX.1 version
337 supported
338 _SC_XBS5_ILP32_OFF32 _XBS_ILP32_OFF32 Indicates support
339 for X/Open ILP32
340 w/32-bit offset
341 build environment
342 _SC_XBS5_ILP32_OFFBIG _XBS5_ILP32_OFFBIG Indicates support
343 for X/Open ILP32
344 w/64-bit offset
345 build environment
346 _SC_XBS5_LP64_OFF64 _XBS5_LP64_OFF64 Indicates support of
347 X/Open LP64,
348 64-bit offset
349 build environment
350 _SC_XBS5_LPBIG_OFFBIG _XBS5_LP64_OFF64 Same as
351 _SC_XBS5_LP64_OFF64
352 _SC_XOPEN_CRYPT _XOPEN_CRYPT Supports X/Open
353 Encryption Feature
354 Group
355 _SC_XOPEN_ENH_I18N _XOPEN_ENH_I18N Supports X/Open
356 Enhanced
357 Internationalization
358 Feature Group
359 _SC_XOPEN_LEGACY _XOPEN_LEGACY Supports X/Open
360 Legacy Feature Group
361 _SC_XOPEN_REALTIME _XOPEN_REALTIME Supports X/Open
362 POSIX Realtime
363 Feature Group
364 _SC_XOPEN_REALTIME_ _XOPEN_REALTIME_THREADS Supports X/Open
365 THREADS POSIX Reatime
366 Threads Feature
367 Group
368 _SC_XOPEN_SHM _XOPEN_SHM Supports X/Open
369 Shared Memory
370 Feature Group
371 _SC_XOPEN_STREAMS _POSIX_XOPEN_STREAMS Supports XSI Streams
372 option group
373 _SC_XOPEN_UNIX _XOPEN_UNIX Supports X/Open CAE
374 Specification,
375 August 1994, System
376 Interfaces and
377 Headers, Issue 4,
378 Version 2
379 _SC_XOPEN_VERSION _XOPEN_VERSION Integer value
380 indicates version of
381 X/Open Portability
382 Guide to which
383 implementation
384 conforms
385 _SC_XOPEN_XCU_VERSION _XOPEN_XCU_VERSION Integer value
386 indicates version of
387 XCU specification to
388 which implementation
389 conforms
390 .fi
391 .in -2
392 .sp
394 .sp
395 .LP
396 The following options are not supported and return \(mi1:
397 .sp
399 .sp
400 .TS
401 l l
402 l l .
403 \fB_SC_2_PBS\fR \fB_POSIX2_PBS\fR
404 \fB_SC_2_PBS_ACCOUNTING\fR \fB_POSIX2_PBS_ACCOUNTING\fR
405 \fB_SC_2_PBS_CHECKPOINT\fR \fB_POSIX2_PBS_CHECKPOINT\fR
406 \fB_SC_2_PBS_LOCATE\fR \fB_POSIX2_PBS_LOCATE\fR
407 \fB_SC_2_PBS_MESSAGE\fR \fB_POSIX2_PBS_MESSAGE\fR
408 \fB_SC_2_PBS_TRACK\fR \fB_POSIX2_PBS_TRACK\fR
409 \fB_SC_ADVISORY_INFO\fR \fB_POSIX_ADVISORY_INFO\fR
410 \fB_SC_CPUTIME\fR \fB_POSIX_CPUTIME\fR
411 \fB_SC_SPORADIC_SERVER\fR \fB_POSIX_SPORADIC_SERVER\fR
412 \fB_SC_SS_REPL_MAX\fR \fB_POSIX_SS_REPL_MAX\fR
413 \fB_SC_THREAD_CPUTIME\fR \fB_POSIX_THREAD_CPUTIME\fR
414 \fB_SC_THREAD_SPORADIC_SERVER\fR \fB_POSIX_THREAD_SPORADIC_SERVER\fR
415 \fB_SC_TRACE\fR \fB_POSIX_TRACE\fR
416 \fB_SC_TRACE_EVENT_FILTER\fR \fB_POSIX_TRACE_EVENT_FILTER\fR
417 \fB_SC_TRACE_EVENT_NAME_MAX\fR \fB_POSIX_TRACE_EVENT_NAME_MAX\fR
418 \fB_SC_TRACE_INHERIT\fR \fB_POSIX_TRACE_INHERIT\fR
419 \fB_SC_TRACE_LOG\fR \fB_POSIX_TRACE_LOG\fR
420 \fB_SC_TRACE_NAME_MAX\fR \fB_POSIX_TRACE_NAME_MAX\fR
421 \fB_SC_TRACE_SYS_MAX\fR \fB_POSIX_TRACE_SYS_MAX\fR
422 \fB_SC_TRACE_USER_EVENT_MAX\fR \fB_POSIX_TRACE_USER_EVENT_MAX\fR
423 \fB_SC_TYPED_MEMORY_OBJECTS\fR \fB_POSIX_TYPED_MEMORY_OBJECTS\fR
424 .TE
426 .SH RETURN VALUES
427 .sp
428 .LP
429 Upon successful completion, \fBsysconf()\fR returns the current variable value
430 on the system. The value returned will not be more restrictive than the
431 corresponding value described to the application when it was compiled with the
432 implementation's <\fBlimits.h\fR>, <\fBunistd.h\fR> or <\fBtime.h\fR>. With
433 only a few obvious exceptions such as \fB_SC_AVPHYS_PAGES\fR and
434 \fB_SC_NPROCESSORS_ONLN\fR, the value will not change during the lifetime of
435 the calling process.
436 .sp
437 .LP
438 If \fIname\fR is an invalid value, \fBsysconf()\fR returns \fB\(mi1\fR and sets
439 \fBerrno\fR to indicate the error. If the variable corresponding to \fIname\fR
440 is associated with functionality that is not supported by the system,
441 \fBsysconf()\fR returns \fB\(mi1\fR without changing the value of \fIerrno\fR.
442 .sp
443 .LP
444 Calling \fBsysconf()\fR with the following returns \fB\(mi1\fR without setting
445 \fBerrno\fR, because no maximum limit can be determined. The system supports at
446 least the minimum values and can support higher values depending upon system
447 resources.
448 .sp
449 .in +2
450 .nf
451 Variable Minimum supported value
452 _SC_AIO_MAX _POSIX_AIO_MAX
453 _SC_ATEXIT_MAX 32
454 _SC_MQ_OPEN_MAX 32
455 _SC_THREAD_THREADS_MAX _POSIX_THREAD_THREADS_MAX
456 _SC_THREAD_KEYS_MAX _POSIX_THREAD_KEYS_MAX
457 _SC_THREAD_DESTRUCTOR_ITERATIONS _POSIX_THREAD_DESTRUCTOR_ITERATIONS
458 .fi
459 .in -2
461 .sp
462 .LP
463 The following SPARC and x86 platform variables return \fBEINVAL\fR:
464 .sp
465 .in +2
466 .nf
467 _SC_COHER_BLKSZ _SC_DCACHE_ASSOC
468 _SC_DCACHE_BLKSZ _SC_DCACHE_LINESZ
469 _SC_DCACHE_SZ _SC_DCACHE_TBLKSZ
470 _SC_ICACHE_ASSOC _SC_ICACHE_BLKSZ
471 _SC_ICACHE_LINESZ _SC_ICACHE_SZ
472 _SC_SPLIT_CACHE
473 .fi
474 .in -2
476 .SH ERRORS
477 .sp
478 .LP
479 The \fBsysconf()\fR function will fail if:
480 .sp
481 .ne 2
482 .na
483 \fB\fBEINVAL\fR\fR
484 .ad
485 .RS 10n
486 The value of the \fIname\fR argument is invalid.
487 .RE
489 .SH ATTRIBUTES
490 .sp
491 .LP
492 See \fBattributes\fR(5) for descriptions of the following attributes:
493 .sp
495 .sp
496 .TS
497 box;
498 c | c
499 l | l .
500 ATTRIBUTE TYPE ATTRIBUTE VALUE
501 _
502 Architecture SPARC and x86
503 _
504 Interface Stability Committed
505 _
506 MT-Level MT-Safe, Async-Signal-Safe
507 _
508 Standard See \fBstandards\fR(5).
509 .TE
511 .SH SEE ALSO
512 .sp
513 .LP
514 \fBpooladm\fR(1M), \fBzoneadm\fR(1M), \fBfpathconf\fR(2), \fBseteuid\fR(2),
515 \fBsetrlimit\fR(2), \fBconfstr\fR(3C), \fBattributes\fR(5), \fBstandards\fR(5)
516 .SH NOTES
517 .sp
518 .LP
519 A call to \fBsetrlimit()\fR can cause the value of \fBOPEN_MAX\fR to change.
520 .sp
521 .LP
522 Multiplying \fBsysconf\fR(\fB_SC_PHYS_PAGES\fR) or
523 \fBsysconf\fR(\fB_SC_AVPHYS_PAGES\fR) by \fBsysconf\fR(\fB_SC_PAGESIZE\fR) to
524 determine memory amount in bytes can exceed the maximum values representable in
525 a 32-bit signed or unsigned integer.
526 .sp
527 .LP
528 The value of \fBCLK_TCK\fR can be variable and it should not be assumed that
529 \fBCLK_TCK\fR is a compile-time constant.
530 .sp
531 .LP
532 If the caller is in a non-global zone and the pools facility is active,
533 \fBsysconf\fR(\fB_SC_NPROCESSORS_CONF\fR) and
534 \fBsysconf\fR(\fB_SC_NPROCESSORS_ONLN\fR) return the number of processors in
535 the processor set of the pool to which the zone is bound.