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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 $
30 .\" $DragonFly: src/lib/libc/gen/sysconf.3,v 1.7 2008/05/02 02:05:03 swildner Exp $
37 .Nd get configurable system variables
43 .Fn sysconf "int name"
45 This interface is defined by
47 A far more complete interface is available using
52 function provides a method for applications to determine the current
53 value of a configurable system limit or option variable.
56 argument specifies the system variable to be queried.
57 Symbolic constants for each name value are found in the include file
60 The available values are as follows:
63 The maximum bytes of argument to
65 .It Li _SC_BC_BASE_MAX
66 The maximum ibase/obase values in the
70 The maximum array size in the
73 .It Li _SC_BC_SCALE_MAX
74 The maximum scale value in the
77 .It Li _SC_BC_STRING_MAX
78 The maximum string length in the
82 The maximum number of simultaneous processes per user id.
84 The frequency of the statistics clock in ticks per second.
85 .It Li _SC_COLL_WEIGHTS_MAX
86 The maximum number of weights that can be assigned to any entry of
87 the LC_COLLATE order keyword in the locale definition file.
88 .It Li _SC_EXPR_NEST_MAX
89 The maximum number of expressions that can be nested within
94 The maximum number of elements in the I/O vector used by
100 .It Li _SC_JOB_CONTROL
101 Return 1 if job control is available on this system, otherwise \-1.
103 The maximum length in bytes of a text-processing utility's input
105 .It Li _SC_MESSAGE_PASSING
106 Whether Message Passing option is supported.
107 .It Li _SC_MQ_OPEN_MAX
108 The maximum number of open message queue descriptors per process.
109 .It Li _SC_MQ_PRIO_MAX
110 The maximum number of message priorities supported by the implementation.
111 .It Li _SC_NGROUPS_MAX
112 The maximum number of supplemental groups.
113 .It Li _SC_NPROCESSORS_CONF
114 The number of processors configured.
115 .It Li _SC_NPROCESSORS_ONLN
116 The number of processors online.
118 The maximum number of open files per user id.
120 The size of a system page in bytes.
121 .It Li _SC_RE_DUP_MAX
122 The maximum number of repeated occurrences of a regular expression
123 permitted when using interval notation.
125 Returns 1 if saved set-group and saved set-user ID is available,
127 .It Li _SC_STREAM_MAX
128 The minimum maximum number of streams that a process may have open
130 .It Li _SC_TZNAME_MAX
131 The minimum maximum number of types supported for the name of a
136 with which the system
139 Return 1 if the system's C-language development facilities support the
140 C-Language Bindings Option, otherwise \-1.
142 Return 1 if the system supports the C-Language Development Utilities Option,
144 .It Li _SC_2_CHAR_TERM
145 Return 1 if the system supports at least one terminal type capable of
146 all operations described in
149 .It Li _SC_2_FORT_DEV
150 Return 1 if the system supports the FORTRAN Development Utilities Option,
152 .It Li _SC_2_FORT_RUN
153 Return 1 if the system supports the FORTRAN Runtime Utilities Option,
155 .It Li _SC_2_LOCALEDEF
156 Return 1 if the system supports the creation of locales, otherwise \-1.
158 Return 1 if the system supports the Software Development Utilities Option,
161 Return 1 if the system supports the User Portability Utilities Option,
166 with which the system attempts to comply.
171 is not successful, \-1 is returned and
173 is set appropriately.
174 Otherwise, if the variable is associated with functionality that is not
175 supported, \-1 is returned and
178 Otherwise, the current variable value is returned.
182 function may fail and set
184 for any of the errors specified for the library function
186 In addition, the following error may be reported:
196 Except for the fact that values returned by
198 may change over the lifetime of the calling process,
199 this function conforms to
202 _SC_NPROCESSORS_CONF and _SC_NPROCESSORS_ONLN are nonstandard, but implemented
207 function first appeared in
210 The value for _SC_STREAM_MAX is a minimum maximum, and required to be
211 the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously
212 small and misleading number.