230 lines
4.8 KiB
HTML
230 lines
4.8 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of STRDUP</TITLE>
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</HEAD><BODY>
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<H1>STRDUP</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2019-03-06<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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strdup, strndup, strdupa, strndupa - duplicate a string
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/string.h">string.h</A>></B>
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<B>char *strdup(const char *</B><I>s</I><B>);</B>
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<B>char *strndup(const char *</B><I>s</I><B>, size_t </B><I>n</I><B>);</B>
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<B>char *strdupa(const char *</B><I>s</I><B>);</B>
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<B>char *strndupa(const char *</B><I>s</I><B>, size_t </B><I>n</I><B>);</B>
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</PRE>
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<P>
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Feature Test Macro Requirements for glibc (see
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<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
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<P>
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<B>strdup</B>():
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<DL COMPACT><DT id="1"><DD>
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_XOPEN_SOURCE >= 500
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<BR> || /* Since glibc 2.12: */ _POSIX_C_SOURCE >= 200809L
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<BR> || /* Glibc versions <= 2.19: */ _BSD_SOURCE || _SVID_SOURCE
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</DL>
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<P>
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<B>strndup</B>():
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<DL COMPACT><DT id="2"><DD>
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<DL COMPACT>
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<DT id="3">Since glibc 2.10:<DD>
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_POSIX_C_SOURCE >= 200809L
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<DT id="4">Before glibc 2.10:<DD>
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_GNU_SOURCE
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</DL>
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</DL>
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<P>
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<B>strdupa</B>(),
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<B>strndupa</B>():
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_GNU_SOURCE
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>strdup</B>()
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function returns a pointer to a new string which
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is a duplicate of the string
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<I>s</I>.
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Memory for the new string is
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obtained with
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<B><A HREF="/cgi-bin/man/man2html?3+malloc">malloc</A></B>(3),
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and can be freed with
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<B><A HREF="/cgi-bin/man/man2html?3+free">free</A></B>(3).
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<P>
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The
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<B>strndup</B>()
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function is similar, but copies at most
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<I>n</I>
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bytes.
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If
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<I>s</I>
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is longer than
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<I>n</I>,
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only
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<I>n</I>
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bytes are copied, and a terminating null byte ('\0') is added.
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<P>
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<B>strdupa</B>()
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and
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<B>strndupa</B>()
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are similar, but use
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<B><A HREF="/cgi-bin/man/man2html?3+alloca">alloca</A></B>(3)
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to allocate the buffer.
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They are available only when using the GNU
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GCC suite, and suffer from the same limitations described in
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<B><A HREF="/cgi-bin/man/man2html?3+alloca">alloca</A></B>(3).
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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On success, the
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<B>strdup</B>()
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function returns a pointer to the duplicated
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string.
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It returns NULL if insufficient memory was available, with
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<I>errno</I>
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set to indicate the cause of the error.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<DL COMPACT>
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<DT id="5"><B>ENOMEM</B>
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<DD>
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Insufficient memory available to allocate duplicate string.
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</DL>
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<A NAME="lbAG"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>strdup</B>(),
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<B>strndup</B>(),
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<B>strdupa</B>(),
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<BR>
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<B>strndupa</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
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</TABLE>
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<P>
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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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<B>strdup</B>()
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conforms to SVr4, 4.3BSD, POSIX.1-2001.
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<B>strndup</B>()
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conforms to POSIX.1-2008.
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<B>strdupa</B>()
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and
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<B>strndupa</B>()
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are GNU extensions.
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<A NAME="lbAI"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+alloca">alloca</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+calloc">calloc</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+free">free</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+malloc">malloc</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+realloc">realloc</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+string">string</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+wcsdup">wcsdup</A></B>(3)
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<A NAME="lbAJ"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="6"><A HREF="#lbAB">NAME</A><DD>
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<DT id="7"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="8"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="9"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="10"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="11"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="12"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="13"><A HREF="#lbAI">SEE ALSO</A><DD>
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<DT id="14"><A HREF="#lbAJ">COLOPHON</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:58 GMT, March 31, 2021
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</BODY>
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</HTML>
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