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28 .\" @(#)sysconf.3 8.3 (Berkeley) 4/19/94
29 .\" $FreeBSD: src/lib/libc/gen/sysconf.3,v 1.8.2.6 2001/12/14 18:33:51 ru Exp $
36 .Nd get configurable system variables
42 .Fn sysconf "int name"
44 This interface is defined by
46 A far more complete interface is available using
51 function provides a method for applications to determine the current
52 value of a configurable system limit or option variable.
55 argument specifies the system variable to be queried.
56 Symbolic constants for each name value are found in the include file
59 The available values are as follows:
62 The maximum bytes of argument to
64 .It Dv _SC_BC_BASE_MAX
65 The maximum ibase/obase values in the
69 The maximum array size in the
72 .It Dv _SC_BC_SCALE_MAX
73 The maximum scale value in the
76 .It Dv _SC_BC_STRING_MAX
77 The maximum string length in the
81 The maximum number of simultaneous processes per user id.
83 The frequency of the statistics clock in ticks per second.
84 .It Dv _SC_COLL_WEIGHTS_MAX
85 The maximum number of weights that can be assigned to any entry of
86 the LC_COLLATE order keyword in the locale definition file.
87 .It Dv _SC_EXPR_NEST_MAX
88 The maximum number of expressions that can be nested within
93 The maximum number of elements in the I/O vector used by
99 .It Dv _SC_JOB_CONTROL
100 Return 1 if job control is available on this system, otherwise \-1.
101 .It Dv _SC_LEVEL1_DCACHE_LINESIZE
102 Returns the L1 cache line size.
104 The maximum length in bytes of a text-processing utility's input
106 .It Dv _SC_MESSAGE_PASSING
107 Whether Message Passing option is supported.
108 .It Dv _SC_MQ_OPEN_MAX
109 The maximum number of open message queue descriptors per process.
110 .It Dv _SC_MQ_PRIO_MAX
111 The maximum number of message priorities supported by the implementation.
112 .It Dv _SC_NGROUPS_MAX
113 The maximum number of supplemental groups.
114 .It Dv _SC_NPROCESSORS_CONF
115 The number of processors configured.
116 .It Dv _SC_NPROCESSORS_ONLN
117 The number of processors online.
119 The maximum number of open files per user id.
121 The size of a system page in bytes.
125 .It Dv _SC_RE_DUP_MAX
126 The maximum number of repeated occurrences of a regular expression
127 permitted when using interval notation.
129 Return 1 if the system supports regular expression handling.
131 Return 1 if saved set-group and saved set-user ID is available,
134 Return 1 if the system supports the
137 .It Dv _SC_STREAM_MAX
138 The minimum maximum number of streams that a process may have open
140 .It Dv _SC_TZNAME_MAX
141 The minimum maximum number of types supported for the name of a
146 with which the system
149 Return 1 if the system supports the
151 Shared Memory Feature
152 for both compilation and execution, or 0 if only compilation support is
155 Return 1 if the system's C-language development facilities support the
156 C-Language Bindings Option, otherwise \-1.
158 Return 1 if the system supports the C-Language Development Utilities Option,
160 .It Dv _SC_2_CHAR_TERM
161 Return 1 if the system supports at least one terminal type capable of
162 all operations described in
165 .It Dv _SC_2_FORT_DEV
166 Return 1 if the system supports the FORTRAN Development Utilities Option,
168 .It Dv _SC_2_FORT_RUN
169 Return 1 if the system supports the FORTRAN Runtime Utilities Option,
171 .It Dv _SC_2_LOCALEDEF
172 Return 1 if the system supports the creation of locales, otherwise \-1.
174 Return 1 if the system supports the Software Development Utilities Option,
177 Return 1 if the system supports the User Portability Utilities Option,
182 with which the system attempts to comply.
185 These values also exist, but may not be standard:
187 .It Dv _SC_PHYS_PAGES
188 The number of pages of physical memory.
193 is not successful, \-1 is returned and
195 is set appropriately.
196 Otherwise, if the variable is associated with functionality that is not
197 supported, \-1 is returned and
200 Otherwise, the current variable value is returned.
204 function may fail and set
206 for any of the errors specified for the library function
208 In addition, the following error may be reported:
218 Except for the fact that values returned by
220 may change over the lifetime of the calling process,
221 this function conforms to
224 .Dv _SC_NPROCESSORS_CONF
226 .Dv _SC_NPROCESSORS_ONLN
227 are nonstandard, but implemented in many systems.
231 function first appeared in
236 is a minimum maximum, and required to be the same as ANSI C's
238 so the returned value is a ridiculously small and misleading number.