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405 lines
8.0 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 FPATHCONF</TITLE>
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</HEAD><BODY>
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<H1>FPATHCONF</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-07-13<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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fpathconf, pathconf - get configuration values for files
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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>long fpathconf(int </B><I>fd</I><B>, int </B><I>name</I><B>);</B>
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<B>long pathconf(const char *</B><I>path</I><B>, int </B><I>name</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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<B>fpathconf</B>()
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gets a value for the configuration option
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<I>name</I>
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for the open file descriptor
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<I>fd</I>.
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<P>
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<B>pathconf</B>()
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gets a value for configuration option
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<I>name</I>
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for the filename
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<I>path</I>.
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<P>
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The corresponding macros defined in
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<I><<A HREF="file:///usr/include/unistd.h">unistd.h</A>></I>
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are minimum values; if an application wants to take advantage of values
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which may change, a call to
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<B>fpathconf</B>()
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or
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<B>pathconf</B>()
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can be made, which may yield more liberal results.
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<P>
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Setting
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<I>name</I>
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equal to one of the following constants returns the following
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configuration options:
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<DL COMPACT>
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<DT id="1"><B>_PC_LINK_MAX</B>
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<DD>
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The maximum number of links to the file.
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If
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<I>fd</I>
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or
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<I>path</I>
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refer to a directory, then the value applies to the whole directory.
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The corresponding macro is
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<B>_POSIX_LINK_MAX</B>.
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<DT id="2"><B>_PC_MAX_CANON</B>
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<DD>
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The maximum length of a formatted input line, where
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<I>fd</I>
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or
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<I>path</I>
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must refer to a terminal.
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The corresponding macro is
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<B>_POSIX_MAX_CANON</B>.
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<DT id="3"><B>_PC_MAX_INPUT</B>
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<DD>
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The maximum length of an input line, where
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<I>fd</I>
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or
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<I>path</I>
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must refer to a terminal.
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The corresponding macro is
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<B>_POSIX_MAX_INPUT</B>.
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<DT id="4"><B>_PC_NAME_MAX</B>
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<DD>
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The maximum length of a filename in the directory
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<I>path</I>
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or
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<I>fd</I>
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that the process is allowed to create.
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The corresponding macro is
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<B>_POSIX_NAME_MAX</B>.
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<DT id="5"><B>_PC_PATH_MAX</B>
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<DD>
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The maximum length of a relative pathname when
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<I>path</I>
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or
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<I>fd</I>
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is the current working directory.
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The corresponding macro is
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<B>_POSIX_PATH_MAX</B>.
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<DT id="6"><B>_PC_PIPE_BUF</B>
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<DD>
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The maximum number of bytes that can be written atomically to a pipe of FIFO.
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For
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<B>fpathconf</B>(),
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<I>fd</I>
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should refer to a pipe or FIFO.
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For
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<B>fpathconf</B>(),
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<I>path</I>
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should refer to a FIFO or a directory; in the latter case,
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the returned value corresponds to FIFOs created in that directory.
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The corresponding macro is
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<B>_POSIX_PIPE_BUF</B>.
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<DT id="7"><B>_PC_CHOWN_RESTRICTED</B>
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<DD>
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This returns a positive value if the use of
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<B><A HREF="/cgi-bin/man/man2html?2+chown">chown</A></B>(2)
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and
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<B><A HREF="/cgi-bin/man/man2html?2+fchown">fchown</A></B>(2)
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for changing a file's user ID is restricted to a process
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with appropriate privileges,
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and changing a file's group ID to a value other than the process's
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effective group ID or one of its supplementary group IDs
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is restricted to a process with appropriate privileges.
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According to POSIX.1,
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this variable shall always be defined with a value other than -1.
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The corresponding macro is
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<B>_POSIX_CHOWN_RESTRICTED</B>.
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<DT id="8"><DD>
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If
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<I>fd</I>
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or
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<I>path</I>
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refers to a directory,
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then the return value applies to all files in that directory.
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<DT id="9"><B>_PC_NO_TRUNC</B>
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<DD>
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This returns nonzero if accessing filenames longer than
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<B>_POSIX_NAME_MAX</B>
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generates an error.
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The corresponding macro is
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<B>_POSIX_NO_TRUNC</B>.
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<DT id="10"><B>_PC_VDISABLE</B>
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<DD>
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This returns nonzero if special character processing can be disabled, where
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<I>fd</I>
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or
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<I>path</I>
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must refer to a terminal.
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</DL>
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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The return value of these functions is one of the following:
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<DL COMPACT>
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<DT id="11">*<DD>
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On error, -1 is returned and
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<I>errno</I>
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is set to indicate the cause of the error
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(for example,
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<B>EINVAL</B>,
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indicating that
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<I>name</I>
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is invalid).
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<DT id="12">*<DD>
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If
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<I>name</I>
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corresponds to a maximum or minimum limit, and that limit is indeterminate,
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-1 is returned and
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<I>errno</I>
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is not changed.
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(To distinguish an indeterminate limit from an error, set
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<I>errno</I>
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to zero before the call, and then check whether
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<I>errno</I>
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is nonzero when -1 is returned.)
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<DT id="13">*<DD>
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If
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<I>name</I>
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corresponds to an option,
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a positive value is returned if the option is supported,
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and -1 is returned if the option is not supported.
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<DT id="14">*<DD>
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Otherwise,
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the current value of the option or limit is returned.
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This value will not be more restrictive than
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the corresponding value that was described to the application in
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<I><<A HREF="file:///usr/include/unistd.h">unistd.h</A>></I>
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or
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<I><<A HREF="file:///usr/include/limits.h">limits.h</A>></I>
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when the application was compiled.
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</DL>
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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="15"><B>EACCES</B>
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<DD>
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(<B>pathconf</B>())
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Search permission is denied for one of the directories in the path prefix of
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<I>path</I>.
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<DT id="16"><B>EBADF</B>
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<DD>
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(<B>fpathconf</B>())
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<I>fd</I>
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is not a valid file descriptor.
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<DT id="17"><B>EINVAL</B>
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<DD>
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<I>name</I>
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is invalid.
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<DT id="18"><B>EINVAL</B>
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<DD>
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The implementation does not support an association of
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<I>name</I>
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with the specified file.
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<DT id="19"><B>ELOOP</B>
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<DD>
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(<B>pathconf</B>())
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Too many symbolic links were encountered while resolving
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<I>path</I>.
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<DT id="20"><B>ENAMETOOLONG</B>
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<DD>
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(<B>pathconf</B>())
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<I>path</I>
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is too long.
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<DT id="21"><B>ENOENT</B>
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<DD>
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(<B>pathconf</B>())
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A component of
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<I>path</I>
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does not exist, or
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<I>path</I>
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is an empty string.
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<DT id="22"><B>ENOTDIR</B>
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<DD>
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(<B>pathconf</B>())
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A component used as a directory in
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<I>path</I>
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is not in fact a directory.
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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>fpathconf</B>(),
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<B>pathconf</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>NOTES</H2>
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Files with name lengths longer than the value returned for
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<I>name</I>
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equal to
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<B>_PC_NAME_MAX</B>
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may exist in the given directory.
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<P>
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Some returned values may be huge; they are not suitable for allocating
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memory.
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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?2+open">open</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+statfs">statfs</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?3+confstr">confstr</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+sysconf">sysconf</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="23"><A HREF="#lbAB">NAME</A><DD>
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<DT id="24"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="25"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="26"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="27"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="28"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="29"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="30"><A HREF="#lbAI">NOTES</A><DD>
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<DT id="31"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="32"><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: 00:05:43 GMT, March 31, 2021
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