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1 | .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk) |
2 | .\" | |
93015253 | 3 | .\" %%%LICENSE_START(VERBATIM) |
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4 | .\" Permission is granted to make and distribute verbatim copies of this |
5 | .\" manual provided the copyright notice and this permission notice are | |
6 | .\" preserved on all copies. | |
7 | .\" | |
8 | .\" Permission is granted to copy and distribute modified versions of this | |
9 | .\" manual under the conditions for verbatim copying, provided that the | |
10 | .\" entire resulting derived work is distributed under the terms of a | |
11 | .\" permission notice identical to this one. | |
c13182ef | 12 | .\" |
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13 | .\" Since the Linux kernel and libraries are constantly changing, this |
14 | .\" manual page may be incorrect or out-of-date. The author(s) assume no | |
15 | .\" responsibility for errors or omissions, or for damages resulting from | |
16 | .\" the use of the information contained herein. The author(s) may not | |
17 | .\" have taken the same level of care in the production of this manual, | |
18 | .\" which is licensed free of charge, as they might when working | |
19 | .\" professionally. | |
c13182ef | 20 | .\" |
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21 | .\" Formatted or processed versions of this manual, if unaccompanied by |
22 | .\" the source, must acknowledge the copyright and authors of this work. | |
4b72fb64 | 23 | .\" %%%LICENSE_END |
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24 | .\" |
25 | .\" References consulted: | |
26 | .\" Linux libc source code | |
27 | .\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) | |
28 | .\" 386BSD man pages | |
29 | .\" Modified Sun Jul 25 10:41:34 1993 by Rik Faith (faith@cs.unc.edu) | |
30 | .\" Modified Wed Oct 17 01:12:26 2001 by John Levon <moz@compsoc.man.ac.uk> | |
97986708 | 31 | .TH STRDUP 3 2016-03-15 "GNU" "Linux Programmer's Manual" |
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32 | .SH NAME |
33 | strdup, strndup, strdupa, strndupa \- duplicate a string | |
34 | .SH SYNOPSIS | |
35 | .nf | |
36 | .B #include <string.h> | |
68e4db0a | 37 | .PP |
fea681da | 38 | .BI "char *strdup(const char *" s ); |
68e4db0a | 39 | .PP |
fea681da MK |
40 | .BI "char *strndup(const char *" s ", size_t " n ); |
41 | .br | |
42 | .BI "char *strdupa(const char *" s ); | |
43 | .br | |
44 | .BI "char *strndupa(const char *" s ", size_t " n ); | |
fea681da | 45 | .fi |
68e4db0a | 46 | .PP |
cc4615cc MK |
47 | .in -4n |
48 | Feature Test Macro Requirements for glibc (see | |
49 | .BR feature_test_macros (7)): | |
50 | .in | |
68e4db0a | 51 | .PP |
8a3a2952 | 52 | .PD 0 |
d5c58392 | 53 | .ad l |
cc4615cc | 54 | .BR strdup (): |
d5c58392 | 55 | .RS 4 |
d59161f9 | 56 | _XOPEN_SOURCE\ >=\ 500 |
cf7fa0a1 | 57 | .\" || _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED |
cf7fa0a1 | 58 | || /* Since glibc 2.12: */ _POSIX_C_SOURCE\ >=\ 200809L |
d59161f9 | 59 | || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE |
d5c58392 MK |
60 | .RE |
61 | .PP | |
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62 | .BR strndup (): |
63 | .RS 4 | |
64 | .TP 4 | |
65 | Since glibc 2.10: | |
b0da7b8b | 66 | _POSIX_C_SOURCE\ >=\ 200809L |
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67 | .TP |
68 | Before glibc 2.10: | |
69 | _GNU_SOURCE | |
70 | .RE | |
71 | .PP | |
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72 | .BR strdupa (), |
73 | .BR strndupa (): | |
74 | _GNU_SOURCE | |
d5c58392 | 75 | .ad |
8a3a2952 | 76 | .PD |
fea681da | 77 | .SH DESCRIPTION |
60a90ecd MK |
78 | The |
79 | .BR strdup () | |
80 | function returns a pointer to a new string which | |
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81 | is a duplicate of the string |
82 | .IR s . | |
1c44bd5b | 83 | Memory for the new string is |
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84 | obtained with |
85 | .BR malloc (3), | |
86 | and can be freed with | |
87 | .BR free (3). | |
847e0d88 | 88 | .PP |
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89 | The |
90 | .BR strndup () | |
33a0ccb2 | 91 | function is similar, but copies at most |
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92 | .I n |
93 | bytes. | |
94 | If | |
95 | .I s | |
96 | is longer than | |
97 | .IR n , | |
98 | only | |
99 | .I n | |
a00b7454 | 100 | bytes are copied, and a terminating null byte (\(aq\\0\(aq) is added. |
847e0d88 | 101 | .PP |
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102 | .BR strdupa () |
103 | and | |
104 | .BR strndupa () | |
105 | are similar, but use | |
106 | .BR alloca (3) | |
c13182ef | 107 | to allocate the buffer. |
33a0ccb2 | 108 | They are available only when using the GNU |
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109 | GCC suite, and suffer from the same limitations described in |
110 | .BR alloca (3). | |
47297adb | 111 | .SH RETURN VALUE |
6a788310 | 112 | On success, the |
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113 | .BR strdup () |
114 | function returns a pointer to the duplicated | |
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115 | string. |
116 | It returns NULL if insufficient memory was available, with | |
117 | .I errno | |
118 | set to indicate the cause of the error. | |
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119 | .SH ERRORS |
120 | .TP | |
121 | .B ENOMEM | |
122 | Insufficient memory available to allocate duplicate string. | |
7ab7eb48 MS |
123 | .SH ATTRIBUTES |
124 | For an explanation of the terms used in this section, see | |
125 | .BR attributes (7). | |
126 | .TS | |
127 | allbox; | |
128 | lbw31 lb lb | |
129 | l l l. | |
130 | Interface Attribute Value | |
131 | T{ | |
132 | .BR strdup (), | |
133 | .BR strndup (), | |
134 | .BR strdupa (), | |
135 | .br | |
136 | .BR strndupa () | |
137 | T} Thread safety MT-Safe | |
138 | .TE | |
847e0d88 | 139 | .sp 1 |
47297adb | 140 | .SH CONFORMING TO |
b14d4aa5 | 141 | .\" 4.3BSD-Reno, not (first) 4.3BSD. |
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142 | .BR strdup () |
143 | conforms to SVr4, 4.3BSD, POSIX.1-2001. | |
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144 | .BR strndup () |
145 | conforms to POSIX.1-2008. | |
146 | .BR strdupa () | |
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147 | and |
148 | .BR strndupa () | |
149 | are GNU extensions. | |
47297adb | 150 | .SH SEE ALSO |
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151 | .BR alloca (3), |
152 | .BR calloc (3), | |
153 | .BR free (3), | |
154 | .BR malloc (3), | |
1709027c | 155 | .BR realloc (3), |
d095200e | 156 | .BR string (3), |
cc4615cc | 157 | .BR wcsdup (3) |