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	1	.\" Copyright (c) 1993
	2	.\" The Regents of the University of California. All rights reserved.
	3	.\"
	4	.\" Redistribution and use in source and binary forms, with or without
	5	.\" modification, are permitted provided that the following conditions
	6	.\" are met:
	7	.\" 1. Redistributions of source code must retain the above copyright
	8	.\" notice, this list of conditions and the following disclaimer.
	9	.\" 2. Redistributions in binary form must reproduce the above copyright
	10	.\" notice, this list of conditions and the following disclaimer in the
	11	.\" documentation and/or other materials provided with the distribution.
	12	.\" 3. All advertising materials mentioning features or use of this software
	13	.\" must display the following acknowledgement:
	14	.\" This product includes software developed by the University of
	15	.\" California, Berkeley and its contributors.
	16	.\" 4. Neither the name of the University nor the names of its contributors
	17	.\" may be used to endorse or promote products derived from this software
	18	.\" without specific prior written permission.
	19	.\"
	20	.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	21	.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	22	.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	23	.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	24	.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	25	.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	26	.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	27	.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	28	.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	29	.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	30	.\" SUCH DAMAGE.
	31	.\"
	32	.\" @(#)confstr.3 8.1 (Berkeley) 6/4/93
	33	.\" $FreeBSD: src/lib/libc/gen/confstr.3,v 1.11 2001/10/01 16:08:50 ru Exp $
	34	.\"
	35	.Dd June 18, 2001
	36	.Dt CONFSTR 3
	37	.Os
	38	.Sh NAME
	39	.Nm confstr
	40	.Nd get string-valued configurable variables
	41	.Sh LIBRARY
	42	.Lb libc
	43	.Sh SYNOPSIS
	44	.In unistd.h
	45	.Ft size_t
	46	.Fn confstr "int name" "char *buf" "size_t len"
	47	.Sh DESCRIPTION
	48	This interface is specified by
	49	.\" .St -p1003.1-200x .
	50	.Tn POSIX .
	51	A more flexible (but non-portable) interface is provided by
	52	.Xr sysctl 3 .
	53	.Pp
	54	The
	55	.Fn confstr
	56	function provides a method for applications to get configuration
	57	defined string values.
	58	Shell programmers needing access to these parameters should use the
	59	.Xr getconf 1
	60	utility.
	61	.Pp
	62	The
	63	.Fa name
	64	argument specifies the system variable to be queried.
	65	Symbolic constants for each name value are found in the include file
	66	.Aq Pa unistd.h .
	67	The
	68	.Fa len
	69	argument specifies the size of the buffer referenced by the
	70	argument
	71	.Fa buf .
	72	If
	73	.Fa len
	74	is non-zero,
	75	.Fa buf
	76	is a non-null pointer, and
	77	.Fa name
	78	has a value, up to
	79	.Fa len
	80	\- 1 bytes of the value are copied into the buffer
	81	.Fa buf .
	82	The copied value is always null terminated.
	83	.Pp
	84	The available values are as follows:
	85	.Pp
	86	.Bl -tag -width 6n
	87	.Pp
	88	.It Li _CS_PATH
	89	Return a value for the
	90	.Ev PATH
	91	environment variable that finds all the standard utilities.
	92	.El
	93	.Sh RETURN VALUES
	94	If the call to
	95	.Fn confstr
	96	is not successful, 0 is returned and
	97	.Va errno
	98	is set appropriately.
	99	Otherwise, if the variable does not have a configuration defined value,
	100	0 is returned and
	101	.Va errno
	102	is not modified.
	103	Otherwise, the buffer size needed to hold the entire configuration-defined
	104	value is returned.
	105	If this size is greater than the argument
	106	.Fa len ,
	107	the string in
	108	.Fa buf
	109	was truncated.
	110	.Sh ERRORS
	111	The
	112	.Fn confstr
	113	function may fail and set
	114	.Va errno
	115	for any of the errors specified for the library functions
	116	.Xr malloc 3
	117	and
	118	.Xr sysctl 3 .
	119	.Pp
	120	In addition, the following errors may be reported:
	121	.Bl -tag -width Er
	122	.It Bq Er EINVAL
	123	The value of the
	124	.Fa name
	125	argument is invalid.
	126	.El
	127	.Sh LEGACY ERRORS
	128	If the call to
	129	.Fn confstr
	130	is not successful, \-1 (rather than 0) is returned and
	131	.Va errno
	132	is set appropriately.
	133	.Sh SEE ALSO
	134	.Xr getconf 1 ,
	135	.Xr pathconf 2 ,
	136	.Xr sysconf 3 ,
	137	.Xr sysctl 3
	138	.Sh HISTORY
	139	The
	140	.Fn confstr
	141	function first appeared in
	142	.Bx 4.4 .