1STRDUP(3)                  Linux Programmer's Manual                 STRDUP(3)
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NAME

6       strdup, strndup, strdupa, strndupa - duplicate a string
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SYNOPSIS

9       #include <string.h>
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11       char *strdup(const char *s);
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13       char *strndup(const char *s, size_t n);
14       char *strdupa(const char *s);
15       char *strndupa(const char *s, size_t n);
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17   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
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19       strdup():
20           _XOPEN_SOURCE >= 500
21               || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
22               || /* Glibc <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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24       strndup():
25           Since glibc 2.10:
26               _POSIX_C_SOURCE >= 200809L
27           Before glibc 2.10:
28               _GNU_SOURCE
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30       strdupa(), strndupa():
31           _GNU_SOURCE
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DESCRIPTION

34       The  strdup() function returns a pointer to a new string which is a du‐
35       plicate of the string s.  Memory for the new string  is  obtained  with
36       malloc(3), and can be freed with free(3).
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38       The strndup() function is similar, but copies at most n bytes.  If s is
39       longer than n, only n bytes are copied, and  a  terminating  null  byte
40       ('\0') is added.
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42       strdupa() and strndupa() are similar, but use alloca(3) to allocate the
43       buffer.  They are available only when using the GNU GCC suite, and suf‐
44       fer from the same limitations described in alloca(3).
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RETURN VALUE

47       On  success,  the strdup() function returns a pointer to the duplicated
48       string.  It returns NULL if insufficient memory was available, with er‐
49       rno set to indicate the error.
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ERRORS

52       ENOMEM Insufficient memory available to allocate duplicate string.
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ATTRIBUTES

55       For  an  explanation  of  the  terms  used  in  this  section,  see at‐
56       tributes(7).
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58       ┌────────────────────────────────────────────┬───────────────┬─────────┐
59       │Interface                                   │ Attribute     │ Value   │
60       ├────────────────────────────────────────────┼───────────────┼─────────┤
61       │strdup(), strndup(), strdupa(), strndupa()  │ Thread safety │ MT-Safe │
62       └────────────────────────────────────────────┴───────────────┴─────────┘
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CONFORMING TO

65       strdup() conforms to SVr4, 4.3BSD, POSIX.1-2001.  strndup() conforms to
66       POSIX.1-2008.  strdupa() and strndupa() are GNU extensions.
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SEE ALSO

69       alloca(3),  calloc(3),  free(3), malloc(3), realloc(3), string(3), wcs‐
70       dup(3)
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COLOPHON

73       This page is part of release 5.12 of the Linux  man-pages  project.   A
74       description  of  the project, information about reporting bugs, and the
75       latest    version    of    this    page,    can     be     found     at
76       https://www.kernel.org/doc/man-pages/.
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80GNU                               2021-03-22                         STRDUP(3)
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