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1 perry 1 SYSCONF
2 !!!SYSCONF
3 NAME
4 SYNOPSIS
5 DESCRIPTION
6 RETURN VALUE
7 CONFORMING TO
8 BUGS
9 SEE ALSO
10 ----
11 !!NAME
12
13
14 sysconf - Get configuration information at runtime
15 !!SYNOPSIS
16
17
18 __#include
19 __ ''name''__);
20 __
21 !!DESCRIPTION
22
23
24 __sysconf()__ provides a way for the application to
25 determine values for system limits or options at
26 runtime.
27
28
29 The equivalent macros defined in ____ can
30 only give conservative values; if an application wants to
31 take advantage of values which may change, a call to
32 __sysconf()__ can be made, which may yield more liberal
33 results.
34
35
36 For getting information about a particular file, see
37 __fpathconf()__ or __pathconf()__.
38
39
40 The following values are supported for ''name''. First,
41 the POSIX.1 compatible values:
42
43
44 ___SC_ARG_MAX__
45
46
47 The maximum length of the arguments to the __exec()__
48 family of functions; the corresponding macro is
49 __ARG_MAX__.
50
51
52 ___SC_CHILD_MAX__
53
54
55 The number of simultaneous processes per user id, the
56 corresponding macro is ___POSIX_CHILD_MAX__.
57
58
59 ___SC_CLK_TCK__
60
61
62 The number of clock ticks per second; the corresponding
63 macro is __CLK_TCK__.
64
65
66 ___SC_STREAM_MAX__
67
68
69 The maximum number of streams that a process can have open
70 at any time. The corresponding POSIX macro is
71 __STREAM_MAX__, the corresponding standard C macro is
72 __FOPEN_MAX__.
73
74
75 ___SC_TZNAME_MAX__
76
77
78 The maximum number of bytes in a timezone name, the
79 corresponding macro is __TZNAME_MAX__.
80
81
82 ___SC_OPEN_MAX__
83
84
85 The maximum number of files that a process can have open at
86 any time, the corresponding macro is
87 ___POSIX_OPEN_MAX__.
88
89
90 ___SC_JOB_CONTROL__
91
92
93 This indicates whether POSIX - style job control is
94 supported, the corresponding macro is
95 ___POSIX_JOB_CONTROL__.
96
97
98 ___SC_SAVED_IDS__
99
100
101 This indicates whether a process has a saved set-user-ID and
102 a saved set-group-ID; the corresponding macro is
103 ___POSIX_SAVED_IDS__.
104
105
106 ___SC_VERSION__
107
108
109 indicates the year and month the POSIX.1 standard was
110 approved in the format __YYYYMML__;__the__ value
111 __199009L__ indicates the most recent revision,
112 1990.
113
114
115 Next, the POSIX.2 values:
116
117
118 ___SC_BC_BASE_MAX__
119
120
121 indicates the maximum ''obase'' value accepted by the
122 bc(1) utility; the corresponding macro is
123 __BC_BASE_MAX__.
124
125
126 ___SC_BC_DIM_MAX__
127
128
129 indicates the maximum value of elements permitted in an
130 array by bc(1); the corresponding macro is
131 __BC_DIM_MAX__.
132
133
134 ___SC_BC_SCALE_MAX__
135
136
137 indicates the maximum ''scale'' value allowed by
138 bc(1); the corresponding macro is
139 __BC_SCALE_MAX__.
140
141
142 ___SC_BC_STRING_MAX__
143
144
145 indicates the maximum length of a string accepted by
146 bc(1); the corresponding macro is
147 __BC_STRING_MAX__.
148
149
150 ___SC_COLL_WEIGHTS_MAX__
151
152
153 indicates the maximum numbers of weights that can be
154 assigned to an entry of the __LC_COLLATE order__ keyword
155 in the locale definition file; the corresponding macro is
156 __COLL_WEIGHTS_MAX__.
157
158
159 ___SC_EXPR_NEST_MAX__
160
161
162 is the maximum number of expressions which can be nested
163 within parentheses by expr(1). The corresponding
164 macro is __EXPR_NEST_MAX__.
165
166
167 ___SC_LINE_MAX__
168
169
170 The maximum length of a utility's input line length, either
171 from standard input or from a file. This includes length for
172 a trailing newline. The corresponding macro is
173 __LINE_MAX__.
174
175
176 ___SC_RE_DUP_MAX__
177
178
179 The maximum number of repeated occurrences of a regular
180 expression when the interval notation __{m,n}__ is used.
181 The value of the corresponding macro is
182 __RE_DUP_MAX__.
183
184
185 ___SC_2_VERSION__
186
187
188 indicates the version of the POSIX.2 standard in the format
189 of YYYYMML. The corresponding macro is
190 __POSIX2_VERSION__.
191
192
193 ___SC_2_DEV__
194
195
196 indicates whether the POSIX.2 C language development
197 facilities are supported. The corresponding macro is
198 __POSIX2_C_DEV__.
199
200
201 ___SC_2_FORT_DEV__
202
203
204 indicates whether the POSIX.2 FORTRAN development utilities
205 are supported. The corresponding macro is
206 __POSIX2_FORT_RUN__.
207
208
209 ___SC_2_FORT_RUN__
210
211
212 indicates whether the POSIX.2 FORTRAN runtime utilities are
213 supported. The corresponding macro is
214 __POSIX2_FORT_RUN__.
215
216
217 ___SC_2_LOCALEDEF__
218
219
220 indicates whether the POSIX.2 creation of locates via
221 localedef(1) is supported. The corresponding macro is
222 ___POSIX2_LOCALEDEF__.
223
224
225 ___SC_2_SW_DEV__
226
227
228 indicates whether the POSIX.2 software development utilities
229 option is supported. The corresponding macro is
230 __POSIX2_SW_DEV__.
231
232
233 SUSv2 also lists
234
235
236 ___SC_PAGESIZE _SC_PAGE_SIZE__
237
238
239 The size of a page (in bytes).
240
241
242 These values also exist, but may not be
243 standard.
244
245
246 ___SC_PHYS_PAGES__
247
248
249 The number of pages of physical memory. Note that it is
250 possible for the product of this value and the value of
251 ___SC_PAGE_SIZE__ to overflow.
252
253
254 ___SC_AVPHYS_PAGES__
255
256
257 The number of currently available pages of physical
258 memory.
259 !!RETURN VALUE
260
261
262 The value returned is the value of the system resource, 1 if
263 a queried option is available, 0 if it is not, or -1 on
264 error. The variable ''errno'' is not set.
265 !!CONFORMING TO
266
267
268 POSIX.1, proposed POSIX.2
269 !!BUGS
270
271
272 It is difficult to use __ARG_MAX__ because it is not
273 specified how much of the argument space for __exec()__
274 is consumed by the user's environment
275 variables.
276
277
278 Some returned values may be huge; they are not suitable for
279 allocating memory.
280
281
282 POSIX.2 is not yet an approved standard; the information in
283 this manpage is subject to change.
284 !!SEE ALSO
285
286
287 bc(1), expr(1), locale(1),
288 fpathconf(3), pathconf(3)
289 ----
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