256 lines
5.9 KiB
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256 lines
5.9 KiB
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of ENVZ_ADD</TITLE>
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</HEAD><BODY>
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<H1>ENVZ_ADD</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<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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envz_add, envz_entry, envz_get, envz_merge,
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envz_remove, envz_strip - environment string support
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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/envz.h">envz.h</A>></B>
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<B>error_t envz_add(char **</B><I>envz</I><B>, size_t *</B><I>envz_len</I><B>,</B>
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<B> const char *</B><I>name</I><B>, const char *</B><I>value</I><B>);</B>
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<B>char *envz_entry(const char *</B><I>envz</I><B>, size_t </B><I>envz_len</I><B>, const char *</B><I>name</I><B>);</B>
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<B>char *envz_get(const char *</B><I>envz</I><B>, size_t </B><I>envz_len</I><B>, const char *</B><I>name</I><B>);</B>
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<B>error_t envz_merge(char **</B><I>envz</I><B>, size_t *</B><I>envz_len</I><B>,</B>
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<B> const char *</B><I>envz2</I><B>, size_t </B><I>envz2_len</I><B>, int </B><I>override</I><B>);</B>
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<B>void envz_remove(char **</B><I>envz</I><B>, size_t *</B><I>envz_len</I><B>, const char *</B><I>name</I><B>);</B>
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<B>void envz_strip(char **</B><I>envz</I><B>, size_t *</B><I>envz_len</I><B>);</B>
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</PRE>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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These functions are glibc-specific.
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<P>
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An argz vector is a pointer to a character buffer together with a length,
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see
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<B><A HREF="/cgi-bin/man/man2html?3+argz_add">argz_add</A></B>(3).
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An envz vector is a special argz vector, namely one where the strings
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have the form "name=value".
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Everything after the first '=' is considered
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to be the value.
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If there is no '=', the value is taken to be NULL.
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(While the value in case of a trailing '=' is the empty string "".)
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<P>
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These functions are for handling envz vectors.
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<P>
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<B>envz_add</B>()
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adds the string
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name = value
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(in case
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<I>value</I>
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is non-NULL) or
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name
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(in case
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<I>value</I>
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is NULL) to the envz vector
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(<I>*envz</I>, <I>*envz_len</I>)
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and updates
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<I>*envz</I>
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and
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<I>*envz_len</I>.
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If an entry with the same
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<I>name</I>
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existed, it is removed.
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<P>
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<B>envz_entry</B>()
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looks for
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<I>name</I>
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in the envz vector
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(<I>envz</I>, <I>envz_len</I>)
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and returns the entry if found, or NULL if not.
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<P>
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<B>envz_get</B>()
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looks for
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<I>name</I>
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in the envz vector
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(<I>envz</I>, <I>envz_len</I>)
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and returns the value if found, or NULL if not.
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(Note that the value can also be NULL, namely when there is
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an entry for
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<I>name</I>
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without '=' sign.)
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<P>
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<B>envz_merge</B>()
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adds each entry in
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<I>envz2</I>
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to
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<I>*envz</I>,
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as if with
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<B>envz_add</B>().
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If
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<I>override</I>
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is true, then values in
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<I>envz2</I>
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will supersede those with the same name in
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<I>*envz</I>,
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otherwise not.
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<P>
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<B>envz_remove</B>()
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removes the entry for
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<I>name</I>
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from
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(<I>*envz</I>, <I>*envz_len</I>)
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if there was one.
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<P>
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<B>envz_strip</B>()
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removes all entries with value NULL.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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All envz functions that do memory allocation have a return type of
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<I>error_t</I>,
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and return 0 for success, and
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<B>ENOMEM</B>
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if an allocation error occurs.
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<A NAME="lbAF"> </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>envz_add</B>(),
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<B>envz_entry</B>(),
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<BR>
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<B>envz_get</B>(),
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<B>envz_merge</B>(),
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<BR>
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<B>envz_remove</B>(),
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<B>envz_strip</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="lbAG"> </A>
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<H2>CONFORMING TO</H2>
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These functions are a GNU extension.
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Handle with care.
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<A NAME="lbAH"> </A>
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<H2>EXAMPLE</H2>
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#include <<A HREF="file:///usr/include/stdio.h">stdio.h</A>>
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#include <<A HREF="file:///usr/include/stdlib.h">stdlib.h</A>>
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#include <<A HREF="file:///usr/include/envz.h">envz.h</A>>
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<P>
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int
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main(int argc, char *argv[], char *envp[])
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{
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<BR> int i, e_len = 0;
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<BR> char *str;
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<P>
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<BR> for (i = 0; envp[i] != NULL; i++)
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<BR> e_len += strlen(envp[i]) + 1;
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<P>
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<BR> str = envz_entry(*envp, e_len, "HOME");
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<BR> printf("%s\n", str);
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<BR> str = envz_get(*envp, e_len, "HOME");
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<BR> printf("%s\n", str);
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<BR> exit(EXIT_SUCCESS);
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}
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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+argz_add">argz_add</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="1"><A HREF="#lbAB">NAME</A><DD>
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<DT id="2"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="3"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="4"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="5"><A HREF="#lbAF">ATTRIBUTES</A><DD>
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<DT id="6"><A HREF="#lbAG">CONFORMING TO</A><DD>
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<DT id="7"><A HREF="#lbAH">EXAMPLE</A><DD>
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<DT id="8"><A HREF="#lbAI">SEE ALSO</A><DD>
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<DT id="9"><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: 00:05:39 GMT, March 31, 2021
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