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28 .\" @(#)sysconf.3 8.3 (Berkeley) 4/19/94
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
58 Shell programmers who need access to these parameters should use the
62 The available values are as follows:
65 The maximum bytes of argument to
68 The maximum number of simultaneous processes per user id.
70 The frequency of the statistics clock in ticks per second.
72 The maximum number of elements in the I/O vector used by
78 .It Li _SC_NGROUPS_MAX
79 The maximum number of supplemental groups.
80 .It Li _SC_NPROCESSORS_CONF
81 The number of processors configured.
82 .It Li _SC_NPROCESSORS_ONLN
83 The number of processors currently online.
85 The maximum number of open files per user id.
87 The size of a system page in bytes.
89 The minimum maximum number of streams that a process may have open
92 The minimum maximum number of types supported for the name of a
94 .It Li _SC_JOB_CONTROL
95 Return 1 if job control is available on this system, otherwise \-1.
97 Returns 1 if saved set-group and saved set-user ID is available,
102 with which the system
104 .It Li _SC_BC_BASE_MAX
105 The maximum ibase/obase values in the
108 .It Li _SC_BC_DIM_MAX
109 The maximum array size in the
112 .It Li _SC_BC_SCALE_MAX
113 The maximum scale value in the
116 .It Li _SC_BC_STRING_MAX
117 The maximum string length in the
120 .It Li _SC_COLL_WEIGHTS_MAX
121 The maximum number of weights that can be assigned to any entry of
122 the LC_COLLATE order keyword in the locale definition file.
123 .It Li _SC_EXPR_NEST_MAX
124 The maximum number of expressions that can be nested within
129 The maximum length in bytes of a text-processing utility's input
131 .It Li _SC_RE_DUP_MAX
132 The maximum number of repeated occurrences of a regular expression
133 permitted when using interval notation.
137 with which the system attempts to comply.
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,
165 These values also exist, but may not be standard:
167 .It Li _SC_PHYS_PAGES
168 The number of pages of physical memory.
169 Note that it is possible that the product of this value and the value of
173 in some configurations on a 32bit machine.
178 is not successful, \-1 is returned and
180 is set appropriately.
181 Otherwise, if the variable is associated with functionality that is not
182 supported, \-1 is returned and
185 Otherwise, the current variable value is returned.
189 function may fail and set
191 for any of the errors specified for the library function
193 In addition, the following error may be reported:
206 Except for the fact that values returned by
208 may change over the lifetime of the calling process,
209 this function conforms to
214 function first appeared in
217 The value for _SC_STREAM_MAX is a minimum maximum, and required to be
218 the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously
219 small and misleading number.