244 lines
5.0 KiB
HTML
244 lines
5.0 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 CONFSTR</TITLE>
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</HEAD><BODY>
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<H1>CONFSTR</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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confstr - get configuration dependent string variables
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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/unistd.h">unistd.h</A>></B>
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<B>size_t confstr(int </B><I>name</I><B>, char *</B><I>buf</I><B>, size_t </B><I>len</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>confstr</B>():
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_POSIX_C_SOURCE >= 2 || _XOPEN_SOURCE
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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<B>confstr</B>()
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gets the value of configuration-dependent string variables.
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<P>
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The
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<I>name</I>
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argument is the system variable to be queried.
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The following variables are supported:
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<DL COMPACT>
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<DT id="1"><B>_CS_GNU_LIBC_VERSION</B> (GNU C library only; since glibc 2.3.2)
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<DD>
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A string which identifies the GNU C library version on this system
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(e.g., "glibc 2.3.4").
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<DT id="2"><B>_CS_GNU_LIBPTHREAD_VERSION</B> (GNU C library only; since glibc 2.3.2)
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<DD>
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A string which identifies the POSIX implementation supplied by this
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C library (e.g., "NPTL 2.3.4" or "linuxthreads-0.10").
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<DT id="3"><B>_CS_PATH</B>
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<DD>
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A value for the
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<B>PATH</B>
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variable which indicates where all the POSIX.2 standard utilities can
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be found.
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</DL>
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<P>
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If
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<I>buf</I>
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is not NULL and
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<I>len</I>
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is not zero,
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<B>confstr</B>()
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copies the value of the string to
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<I>buf</I>
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truncated to
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<I>len - 1</I>
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bytes if necessary, with a null byte ('\0') as terminator.
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This can be detected by comparing the return value of
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<B>confstr</B>()
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against
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<I>len</I>.
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<P>
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If
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<I>len</I>
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is zero and
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<I>buf</I>
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is NULL,
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<B>confstr</B>()
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just returns the value as defined below.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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If
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<I>name</I>
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is a valid configuration variable,
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<B>confstr</B>()
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returns the number of bytes (including the terminating null byte)
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that would be required to hold the entire value of that variable.
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This value may be greater than
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<I>len</I>,
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which means that the value in
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<I>buf</I>
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is truncated.
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<P>
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If
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<I>name</I>
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is a valid configuration variable,
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but that variable does not have a value, then
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<B>confstr</B>()
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returns 0.
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If
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<I>name</I>
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does not correspond to a valid configuration variable,
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<B>confstr</B>()
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returns 0, and
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<I>errno</I>
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is set to
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<B>EINVAL</B>.
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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="4"><B>EINVAL</B>
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<DD>
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The value of
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<I>name</I>
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is invalid.
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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>confstr</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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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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POSIX.1-2001, POSIX.1-2008.
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<A NAME="lbAI"> </A>
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<H2>EXAMPLE</H2>
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The following code fragment determines the path where to find
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the POSIX.2 system utilities:
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<P>
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char *pathbuf;
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size_t n;
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<P>
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n = confstr(_CS_PATH, NULL, (size_t) 0);
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pathbuf = <A HREF="/cgi-bin/man/man2html?n+malloc">malloc</A>(n);
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if (pathbuf == NULL)
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<BR> abort();
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confstr(_CS_PATH, pathbuf, n);
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?1+getconf">getconf</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?1+sh">sh</A></B>(1),
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<B><A HREF="/cgi-bin/man/man2html?3+exec">exec</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+fpathconf">fpathconf</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+pathconf">pathconf</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sysconf">sysconf</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+system">system</A></B>(3)
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<A NAME="lbAK"> </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="5"><A HREF="#lbAB">NAME</A><DD>
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<DT id="6"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="7"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="8"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="9"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="10"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="11"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="12"><A HREF="#lbAI">EXAMPLE</A><DD>
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<DT id="13"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="14"><A HREF="#lbAK">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: 00:05:38 GMT, March 31, 2021
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</BODY>
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</HTML>
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