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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. | |
c13182ef | 11 | .\" |
fea681da MK |
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13 | .\" manual page may be incorrect or out-of-date.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. | |
c13182ef | 19 | .\" |
fea681da MK |
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) | |
c13182ef | 24 | .\" FIXME Many more values for 'name' are supported, some of which |
5984622e | 25 | .\" are documented under 'info confstr'. |
c13182ef | 26 | .\" See <bits/confname.h> for the rest. |
0359df8c | 27 | .\" These should all be added to this page. |
68e1685c | 28 | .\" See also the POSIX.1-2001 specification of confstr() |
cc4615cc | 29 | .TH CONFSTR 3 2007-07-26 "GNU" "Linux Programmer's Manual" |
fea681da MK |
30 | .SH NAME |
31 | confstr \- get configuration dependent string variables | |
32 | .SH SYNOPSIS | |
33 | .nf | |
fea681da MK |
34 | .B #include <unistd.h> |
35 | .sp | |
36 | .BI "size_t confstr(int " "name" ", char *" buf ", size_t " len ); | |
37 | .fi | |
cc4615cc MK |
38 | .sp |
39 | .in -4n | |
40 | Feature Test Macro Requirements for glibc (see | |
41 | .BR feature_test_macros (7)): | |
42 | .in | |
43 | .sp | |
44 | .BR getcwd (): | |
45 | _POSIX_C_SOURCE\ >=\ 2 || _XOPEN_SOURCE | |
fea681da | 46 | .SH DESCRIPTION |
63aa9df0 | 47 | .BR confstr () |
fea681da MK |
48 | gets the value of configuration-dependent string variables. |
49 | .PP | |
50 | The | |
51 | .I name | |
52 | argument is the system variable to be queried. | |
53 | The following variables are supported: | |
54 | .TP | |
5984622e MK |
55 | .BR _CS_GNU_LIBC_VERSION " (GNU C library only; since glibc 2.3.2)" |
56 | A string which identifies the GNU C library version on this system | |
57 | (e.g, "glibc 2.3.4"). | |
58 | .TP | |
59 | .BR _CS_GNU_LIBPTHREAD_VERSION " (GNU C library only; since glibc 2.3.2)" | |
60 | A string which identifies the POSIX implementation supplied by this | |
61 | C library (e.g, "NPTL 2.3.4" or "linuxthreads-0.10"). | |
62 | .TP | |
fea681da MK |
63 | .B _CS_PATH |
64 | A value for the | |
65 | .B PATH | |
66 | variable which indicates where all the POSIX.2 standard utilities can | |
67 | be found. | |
68 | .PP | |
69 | If | |
70 | .I buf | |
c13182ef | 71 | is not NULL and |
fea681da MK |
72 | .I len |
73 | is not zero, | |
63aa9df0 | 74 | .BR confstr () |
fea681da MK |
75 | copies the value of the string to |
76 | .I buf | |
77 | truncated to | |
78 | .I len \- 1 | |
28d88c17 | 79 | characters if necessary, with a null byte ('\\0') as terminator. |
fea681da | 80 | This can be detected by comparing the return value of |
63aa9df0 | 81 | .BR confstr () |
fea681da MK |
82 | against |
83 | .IR len . | |
84 | .PP | |
85 | If | |
86 | .I len | |
87 | is zero and | |
88 | .I buf | |
8478ee02 | 89 | is NULL, |
63aa9df0 | 90 | .BR confstr () |
fea681da MK |
91 | just returns the value as defined below. |
92 | .SH "RETURN VALUE" | |
93 | If | |
94 | .I name | |
4f43f21f | 95 | is a valid configuration variable, |
63aa9df0 | 96 | .BR confstr () |
c13182ef | 97 | returns the number of bytes (including the terminating null byte) |
4f43f21f MK |
98 | that would be required to hold the entire value of that variable. |
99 | This value may be greater than | |
100 | .IR len , | |
101 | which means that the value in | |
102 | .I buf | |
103 | is truncated. | |
104 | ||
105 | If | |
c13182ef MK |
106 | .I name |
107 | is a valid configuration variable, | |
4f43f21f | 108 | but that variable does not have a value, then |
01a81d11 | 109 | .BR confstr () |
fea681da | 110 | returns 0. |
4f43f21f MK |
111 | If |
112 | .I name | |
113 | does not correspond to a valid configuration variable, | |
114 | .BR confstr () | |
115 | returns 0, and | |
116 | .I errno | |
c13182ef | 117 | is set to |
4f43f21f MK |
118 | .BR EINVAL . |
119 | .SH ERRORS | |
01a81d11 | 120 | .TP |
0daa9e92 | 121 | .B EINVAL |
4f43f21f MK |
122 | If the value of |
123 | .I name | |
124 | is invalid. | |
2b2581ee MK |
125 | .SH "CONFORMING TO" |
126 | POSIX.1-2001 | |
9b336505 | 127 | .SH EXAMPLE |
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128 | The following code fragment determines the path where to find |
129 | the POSIX.2 system utilities: | |
130 | .br | |
131 | .nf | |
132 | .in 10 | |
133 | ||
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134 | char *pathbuf; |
135 | size_t n; | |
fea681da | 136 | |
56e83639 | 137 | n = confstr(_CS_PATH,NULL,(size_t) 0); |
6cd17cde MK |
138 | pathbuf = malloc(n); |
139 | if (pathbuf == NULL) | |
140 | abort(); | |
fea681da | 141 | confstr(_CS_PATH, pathbuf, n); |
fea681da MK |
142 | .SH "SEE ALSO" |
143 | .BR sh (1), | |
144 | .BR exec (3), | |
cc4615cc | 145 | .BR system (3) |