[thirdparty/man-pages.git] / man3 / confstr.3

.\" (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
.\"
.\" Permission is granted to make and distribute verbatim copies of this
.\" manual provided the copyright notice and this permission notice are
.\" preserved on all copies.
.\"
.\" Permission is granted to copy and distribute modified versions of this
.\" manual under the conditions for verbatim copying, provided that the
.\" entire resulting derived work is distributed under the terms of a
.\" permission notice identical to this one.
.\" 
.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
.\" responsibility for errors or omissions, or for damages resulting from
.\" the use of the information contained herein.  The author(s) may not
.\" have taken the same level of care in the production of this manual,
.\" which is licensed free of charge, as they might when working
.\" professionally.
.\" 
.\" Formatted or processed versions of this manual, if unaccompanied by
.\" the source, must acknowledge the copyright and authors of this work.
.\" License.
.\" Modified Sat Jul 24 19:53:02 1993 by Rik Faith (faith@cs.unc.edu)
.\" FIXME Many more values for 'name' are supported, some of which 
.\"	are documented under 'info confstr'.
.\"	See <bits/confname.h> for the rest.  
.\"	These should all be added to this page.
.\"	See also the SUSv3 specification of confstr()
.TH CONFSTR 3  1993-04-17 "GNU" "Linux Programmer's Manual"
.SH NAME
confstr \- get configuration dependent string variables
.SH SYNOPSIS
.nf
.B #define _POSIX_C_SOURCE 2
or
.B #define _XOPEN_SOURCE
.nl
.B #include <unistd.h>
.sp
.BI "size_t confstr(int " "name" ", char *" buf ", size_t " len );
.fi
.SH DESCRIPTION
.B confstr()
gets the value of configuration-dependent string variables.
.PP
The
.I name
argument is the system variable to be queried.
The following variables are supported:
.TP
.BR _CS_GNU_LIBC_VERSION " (GNU C library only; since glibc 2.3.2)"
A string which identifies the GNU C library version on this system
(e.g, "glibc 2.3.4").
.TP
.BR _CS_GNU_LIBPTHREAD_VERSION " (GNU C library only; since glibc 2.3.2)"
A string which identifies the POSIX implementation supplied by this
C library (e.g, "NPTL 2.3.4" or "linuxthreads-0.10").
.TP
.B _CS_PATH
A value for the
.B PATH
variable which indicates where all the POSIX.2 standard utilities can
be found.
.PP
If
.I buf
is not
.BR NULL ,
and 
.I len
is not zero,
.B confstr()
copies the value of the string to
.I buf
truncated to
.I len \- 1
characters if necessary, with a null character as termination.
This can be detected by comparing the return value of
.B confstr()
against
.IR len .
.PP
If
.I len
is zero and
.I buf
is 
.BR NULL ,
.B confstr()
just returns the value as defined below.
.SH "RETURN VALUE"
If
.I name
does not correspond to a valid configuration variable,
.B confstr()
returns 0.
.SH EXAMPLES
The following code fragment determines the path where to find
the POSIX.2 system utilities:
.br
.nf
.in 10

char *pathbuf; size_t n;

n = confstr(_CS_PATH,NULL,(size_t)0);
if ((pathbuf = malloc(n)) == NULL) abort();
confstr(_CS_PATH, pathbuf, n);
.SH ERRORS
If the value of
.I name
is invalid,
.I errno
is set to
.BR EINVAL .
.SH "CONFORMING TO"
proposed POSIX.2
.SH BUGS
POSIX.2 is not yet an approved standard; the information in this
manpage is subject to change.
.SH "SEE ALSO"
.BR sh (1),
.BR exec (3),
.BR system (3)
Commit	Line	Data
fea681da MK	1	.\" (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
	2	.\"
	3	.\" Permission is granted to make and distribute verbatim copies of this
	4	.\" manual provided the copyright notice and this permission notice are
	5	.\" preserved on all copies.
	6	.\"
	7	.\" Permission is granted to copy and distribute modified versions of this
	8	.\" manual under the conditions for verbatim copying, provided that the
	9	.\" entire resulting derived work is distributed under the terms of a
	10	.\" permission notice identical to this one.
	11	.\"
	12	.\" Since the Linux kernel and libraries are constantly changing, this
	13	.\" manual page may be incorrect or out-of-date. The author(s) assume no
	14	.\" responsibility for errors or omissions, or for damages resulting from
	15	.\" the use of the information contained herein. The author(s) may not
	16	.\" have taken the same level of care in the production of this manual,
	17	.\" which is licensed free of charge, as they might when working
	18	.\" professionally.
	19	.\"
	20	.\" Formatted or processed versions of this manual, if unaccompanied by
	21	.\" the source, must acknowledge the copyright and authors of this work.
	22	.\" License.
	23	.\" Modified Sat Jul 24 19:53:02 1993 by Rik Faith (faith@cs.unc.edu)
5984622e MK	24	.\" FIXME Many more values for 'name' are supported, some of which
	25	.\" are documented under 'info confstr'.
	26	.\" See <bits/confname.h> for the rest.
0359df8c	27	.\" These should all be added to this page.
5984622e	28	.\" See also the SUSv3 specification of confstr()
fea681da MK	29	.TH CONFSTR 3 1993-04-17 "GNU" "Linux Programmer's Manual"
	30	.SH NAME
	31	confstr \- get configuration dependent string variables
	32	.SH SYNOPSIS
	33	.nf
	34	.B #define _POSIX_C_SOURCE 2
	35	or
	36	.B #define _XOPEN_SOURCE
	37	.nl
	38	.B #include <unistd.h>
	39	.sp
	40	.BI "size_t confstr(int " "name" ", char *" buf ", size_t " len );
	41	.fi
	42	.SH DESCRIPTION
	43	.B confstr()
	44	gets the value of configuration-dependent string variables.
	45	.PP
	46	The
	47	.I name
	48	argument is the system variable to be queried.
	49	The following variables are supported:
	50	.TP
5984622e MK	51	.BR _CS_GNU_LIBC_VERSION " (GNU C library only; since glibc 2.3.2)"
	52	A string which identifies the GNU C library version on this system
	53	(e.g, "glibc 2.3.4").
	54	.TP
	55	.BR _CS_GNU_LIBPTHREAD_VERSION " (GNU C library only; since glibc 2.3.2)"
	56	A string which identifies the POSIX implementation supplied by this
	57	C library (e.g, "NPTL 2.3.4" or "linuxthreads-0.10").
	58	.TP
fea681da MK	59	.B _CS_PATH
	60	A value for the
	61	.B PATH
	62	variable which indicates where all the POSIX.2 standard utilities can
	63	be found.
	64	.PP
	65	If
	66	.I buf
	67	is not
	68	.BR NULL ,
	69	and
	70	.I len
	71	is not zero,
	72	.B confstr()
	73	copies the value of the string to
	74	.I buf
	75	truncated to
	76	.I len \- 1
	77	characters if necessary, with a null character as termination.
	78	This can be detected by comparing the return value of
	79	.B confstr()
	80	against
	81	.IR len .
	82	.PP
	83	If
	84	.I len
	85	is zero and
	86	.I buf
	87	is
	88	.BR NULL ,
	89	.B confstr()
	90	just returns the value as defined below.
	91	.SH "RETURN VALUE"
	92	If
	93	.I name
	94	does not correspond to a valid configuration variable,
	95	.B confstr()
	96	returns 0.
	97	.SH EXAMPLES
	98	The following code fragment determines the path where to find
	99	the POSIX.2 system utilities:
	100	.br
	101	.nf
	102	.in 10
	103
	104	char *pathbuf; size_t n;
	105
	106	n = confstr(_CS_PATH,NULL,(size_t)0);
	107	if ((pathbuf = malloc(n)) == NULL) abort();
	108	confstr(_CS_PATH, pathbuf, n);
	109	.SH ERRORS
	110	If the value of
	111	.I name
	112	is invalid,
	113	.I errno
	114	is set to
	115	.BR EINVAL .
	116	.SH "CONFORMING TO"
	117	proposed POSIX.2
	118	.SH BUGS
	119	POSIX.2 is not yet an approved standard; the information in this
	120	manpage is subject to change.
	121	.SH "SEE ALSO"
	122	.BR sh (1),
123	.BR exec (3),
124	.BR system (3)