Annotation of src/lib/libc/gen/sysconf.3, Revision 1.23
1.23 ! wiz 1: .\" $NetBSD: sysconf.3,v 1.22 2003/02/02 20:33:07 kleink Exp $
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34: .\" @(#)sysconf.3 8.3 (Berkeley) 4/19/94
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1.22 kleink 36: .Dd February 2, 2003
1.1 cgd 37: .Dt SYSCONF 3
1.11 garbled 38: .Os
1.1 cgd 39: .Sh NAME
40: .Nm sysconf
41: .Nd get configurable system variables
1.6 perry 42: .Sh LIBRARY
43: .Lb libc
1.1 cgd 44: .Sh SYNOPSIS
1.19 ross 45: .Fd #include \*[Lt]unistd.h\*[Gt]
1.1 cgd 46: .Ft long
47: .Fn sysconf "int name"
48: .Sh DESCRIPTION
49: This interface is defined by
50: .St -p1003.1-88 .
51: A far more complete interface is available using
52: .Xr sysctl 3 .
53: .Pp
54: The
55: .Fn sysconf
56: function provides a method for applications to determine the current
57: value of a configurable system limit or option variable.
58: The
59: .Fa name
60: argument specifies the system variable to be queried.
61: Symbolic constants for each name value are found in the include file
1.19 ross 62: .Li \*[Lt]unistd.h\*[Gt] .
1.1 cgd 63: .Pp
64: The available values are as follows:
65: .Pp
66: .Bl -tag -width "123456"
67: .Pp
68: .It Li _SC_ARG_MAX
69: The maximum bytes of argument to
1.7 fair 70: .Xr execve 2 .
1.21 kleink 71: .It Li _SC_ATEXIT_MAX
72: The maxmimum number of functions that may be registered with
73: .Xr atexit 3 .
1.22 kleink 74: .It Li _SC_BARRIERS
75: The version of
1.23 ! wiz 76: .St -p1003.1
! 77: and its
1.22 kleink 78: Barriers
79: option to which the system attempts to conform,
80: otherwise \-1.
1.1 cgd 81: .It Li _SC_CHILD_MAX
82: The maximum number of simultaneous processes per user id.
83: .It Li _SC_CLK_TCK
1.3 jtc 84: The number of clock ticks per second.
1.9 kleink 85: .It Li _SC_FSYNC
86: Return 1 if the File Synchronization Option is available on this system,
87: otherwise \-1.
88: .It Li _SC_IOV_MAX
89: The maximum number of
90: .Va iovec
91: structures that a process has available for use with
92: .Xr preadv 2 ,
93: .Xr pwritev 2 ,
94: .Xr readv 2 ,
95: .Xr recvmsg 2 ,
96: .Xr sendmsg 2
97: or
98: .Xr writev 2 .
99: .It Li _SC_JOB_CONTROL
100: Return 1 if job control is available on this system, otherwise \-1.
1.13 kleink 101: .It Li _SC_LOGIN_NAME_MAX
102: Returns the size of the storage required for a login name, in bytes,
103: including the terminating NUL.
1.12 kleink 104: .It Li _SC_MAPPED_FILES
105: Return 1 if the Memory Mapped Files Option is available on this system,
106: otherwise \-1.
107: .It Li _SC_MEMLOCK
108: Return 1 if the Process Memory Locking Option is available on this system,
109: otherwise \-1.
110: .It Li _SC_MEMLOCK_RANGE
111: Return 1 if the Range Memory Locking Option is available on this system,
112: otherwise \-1.
113: .It Li _SC_MEMORY_PROTECTION
114: Return 1 if the Memory Protection Option is available on this system,
115: otherwise \-1.
1.18 kleink 116: .It Li _SC_MONOTONIC_CLOCK
1.20 kleink 117: Return the
118: .Tn POSIX
119: version the implementation of the Monotonic Clock Option
120: on this system conforms to,
1.18 kleink 121: or \-1 if unavailable.
1.1 cgd 122: .It Li _SC_NGROUPS_MAX
123: The maximum number of supplemental groups.
124: .It Li _SC_OPEN_MAX
1.15 kleink 125: The maximum number of open files per process.
1.9 kleink 126: .It Li _SC_PAGESIZE
127: The size of a system page in bytes.
1.22 kleink 128: .It Li _SC_READER_WRITER_LOCKS
129: The version of
1.23 ! wiz 130: .St -p1003.1
! 131: and its
1.22 kleink 132: Read-Write Locks
133: option to which the system attempts to conform,
134: otherwise \-1.
135: .It Li _SC_SEMAPHORES
136: The version of
1.23 ! wiz 137: .St -p1003.1
! 138: and its
1.22 kleink 139: Semaphores
140: option to which the system attempts to conform,
141: otherwise \-1.
142: .It Li _SC_SPIN_LOCKS
143: The version of
1.23 ! wiz 144: .St -p1003.1
! 145: and its
1.22 kleink 146: Spin Locks
147: option to which the system attempts to conform,
148: otherwise \-1.
1.1 cgd 149: .It Li _SC_STREAM_MAX
150: The minimum maximum number of streams that a process may have open
151: at any one time.
1.9 kleink 152: .It Li _SC_SYNCHRONIZED_IO
153: Return 1 if the Synchronized I/O Option is available on this system,
1.22 kleink 154: otherwise \-1.
155: .It Li _SC_THREADS
156: The version of
1.23 ! wiz 157: .St -p1003.1
! 158: and its
1.22 kleink 159: Threads
160: option to which the system attempts to conform,
161: otherwise \-1.
162: .It Li _SC_TIMERS
163: The version of
1.23 ! wiz 164: .St -p1003.1
! 165: and its
1.22 kleink 166: Timers
167: option to which the system attempts to conform,
1.9 kleink 168: otherwise \-1.
1.1 cgd 169: .It Li _SC_TZNAME_MAX
170: The minimum maximum number of types supported for the name of a
171: timezone.
172: .It Li _SC_SAVED_IDS
173: Returns 1 if saved set-group and saved set-user ID is available,
174: otherwise \-1.
175: .It Li _SC_VERSION
176: The version of ISO/IEC 9945 (POSIX 1003.1) with which the system
177: attempts to comply.
1.14 kleink 178: .It Li _SC_XOPEN_SHM
179: Return 1 of the system supports System V style shared memory,
180: otherwise \-1.
1.1 cgd 181: .It Li _SC_BC_BASE_MAX
182: The maximum ibase/obase values in the
183: .Xr bc 1
184: utility.
185: .It Li _SC_BC_DIM_MAX
186: The maximum array size in the
187: .Xr bc 1
188: utility.
189: .It Li _SC_BC_SCALE_MAX
190: The maximum scale value in the
191: .Xr bc 1
192: utility.
193: .It Li _SC_BC_STRING_MAX
194: The maximum string length in the
195: .Xr bc 1
196: utility.
197: .It Li _SC_COLL_WEIGHTS_MAX
198: The maximum number of weights that can be assigned to any entry of
199: the LC_COLLATE order keyword in the locale definition file.
200: .It Li _SC_EXPR_NEST_MAX
201: The maximum number of expressions that can be nested within
202: parenthesis by the
203: .Xr expr 1
204: utility.
205: .It Li _SC_LINE_MAX
206: The maximum length in bytes of a text-processing utility's input
207: line.
208: .It Li _SC_RE_DUP_MAX
209: The maximum number of repeated occurrences of a regular expression
210: permitted when using interval notation.
211: .It Li _SC_2_VERSION
212: The version of POSIX 1003.2 with which the system attempts to comply.
1.16 wiz 213: .It Li _SC_2_C_BIND
1.1 cgd 214: Return 1 if the system's C-language development facilities support the
215: C-Language Bindings Option, otherwise \-1.
216: .It Li _SC_2_C_DEV
217: Return 1 if the system supports the C-Language Development Utilities Option,
218: otherwise \-1.
219: .It Li _SC_2_CHAR_TERM
220: Return 1 if the system supports at least one terminal type capable of
221: all operations described in POSIX 1003.2, otherwise \-1.
222: .It Li _SC_2_FORT_DEV
223: Return 1 if the system supports the FORTRAN Development Utilities Option,
224: otherwise \-1.
225: .It Li _SC_2_FORT_RUN
226: Return 1 if the system supports the FORTRAN Runtime Utilities Option,
227: otherwise \-1.
228: .It Li _SC_2_LOCALEDEF
229: Return 1 if the system supports the creation of locales, otherwise \-1.
230: .It Li _SC_2_SW_DEV
231: Return 1 if the system supports the Software Development Utilities Option,
232: otherwise \-1.
233: .It Li _SC_2_UPE
234: Return 1 if the system supports the User Portability Utilities Option,
1.9 kleink 235: otherwise \-1.
1.1 cgd 236: .El
237: .Sh RETURN VALUES
238: If the call to
239: .Nm sysconf
240: is not successful, \-1 is returned and
241: .Va errno
242: is set appropriately.
243: Otherwise, if the variable is associated with functionality that is not
244: supported, \-1 is returned and
245: .Va errno
246: is not modified.
247: Otherwise, the current variable value is returned.
248: .Sh ERRORS
249: The
250: .Fn sysconf
251: function may fail and set
252: .Va errno
253: for any of the errors specified for the library functions
254: .Xr sysctl 3 .
255: In addition, the following error may be reported:
256: .Bl -tag -width Er
257: .It Bq Er EINVAL
258: The value of the
259: .Fa name
260: argument is invalid.
1.10 erh 261: .El
1.1 cgd 262: .Sh SEE ALSO
263: .Xr sysctl 3
264: .Sh STANDARDS
265: The
266: .Fn sysconf
267: function conforms to
1.4 kleink 268: .St -p1003.1-90 .
1.1 cgd 269: .Sh HISTORY
270: The
271: .Nm sysconf
1.5 perry 272: function first appeared in
273: .Bx 4.4 .
1.17 wiz 274: .Sh BUGS
275: The value for _SC_STREAM_MAX is a minimum maximum, and required to be
276: the same as ANSI C's FOPEN_MAX, so the returned value is a ridiculously
277: small and misleading number.
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