280 lines
6.2 KiB
HTML
280 lines
6.2 KiB
HTML
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<head>
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<!-- This file has been generated by unroff 1.0, 03/21/96 19:25:27. -->
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<!-- Do not edit! -->
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<link rev="made" href="mailto:net@informatik.uni-bremen.de">
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<!-- t -->
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<!-- @(#)pathconf.2v 1.20 90/02/15 SMI; new for 4.1, POSIX -->
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<title>Manual page for PATHCONF(2V)</title>
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</head>
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<body>
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<h2>
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pathconf, fpathconf - query file system related limits and options
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<hr></h2>
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<h2>SYNOPSIS</h2>
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<pre>
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<b>#include <unistd.h>
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</b></pre>
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<p>
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<pre>
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<b>long pathconf(path, name)
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char *path;
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int name;
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</b></pre>
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<p>
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<pre>
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<b>long fpathconf(fd, name)
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int fd, name;
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</b></pre>
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<h2>DESCRIPTION</h2>
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<p>
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<b>pathconf()
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</b>and
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<b>fpathconf()
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</b>provide a
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method for the application to determine the current value of a
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configurable limit or option that is associated with a file
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or directory,
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<p>
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For
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<b>pathconf()</b>,
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<i>path
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</i>points to the pathname of a file or
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directory.<tt> </tt>
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For
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<b>fpathconf()</b>,
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<i>fd
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</i>is an open file descriptor.<tt> </tt>
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<p>
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The convention used throughout sections 2 and 3
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is that
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{LIMIT}
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means that
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LIMIT
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is something that
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can change from file to file (due to multiple file systems on the same
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machine). The actual value for
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LIMIT is typically
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not defined in any header file since
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it is not invariant. Instead, pathconf must be called to retrieve the value.<tt> </tt>
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<b>pathconf()
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</b>understands a list of flags that are named similarly to the value
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being queried.
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<p>
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The following table lists the name and meaning of each conceptual limit.<tt> </tt>
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<p>
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<dl><dt><dd>
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<pre>
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Limit Meaning
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------------------------------------------------------------------------
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{LINK_MAX} Max links to an object.
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{MAX_CANON} Max tty input line size.
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{MAX_INPUT} Max packet a tty can accept at once.
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{NAME_MAX} Max filename length.
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{PATH_MAX} Max pathname length.
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{PIPE_BUF} Pipe buffer size.
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{_POSIX_CHOWN_RESTRICTED} If true only root can chown() files, other<65>
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wise anyone may give away files.
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{_POSIX_NO_TRUNC} If false filenames > {NAME_MAX} are trun<75>
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cated, otherwise an error.
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{_POSIX_VDISABLE} A char to use to disable tty special chars.
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</pre>
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</dl>
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<p>
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The following table lists the name of each limit, the flag
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passed to
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<b>pathconf()
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</b>to retrieve the value of each variable, and some notes about usage.<tt> </tt>
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<p>
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<dl><dt><dd>
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<pre>
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Limit Pathconf Flag Notes
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---------------------------------------------------------
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{LINK_MAX} _PC_LINK_MAX 1
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{MAX_CANON} _PC_MAX_CANON 2
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{MAX_INPUT} _PC_MAX_INPUT 2
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{NAME_MAX} _PC_NAME_MAX 3,4
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{PATH_MAX} _PC_PATH_MAX 4,5
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{PIPE_BUF} _PC_PIPE_BUF 6
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{_POSIX_CHOWN_RESTRICTED} _PC_CHOWN_RESTRICTED 7,8
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{_POSIX_NO_TRUNC} _PC_NO_TRUNC 3,4,8
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{_POSIX_VDISABLE} _PC_VDISABLE 2,8
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</pre>
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</dl>
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<p>
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<p>
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The following notes apply to the entries in the preceding table.<tt> </tt>
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<p>
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<dl>
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<dt>1
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<dd>
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If
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<i>path
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</i>or
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<i>fd
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</i>refers to a directory, the value returned applies to the
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directory itself.<tt> </tt>
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<dt>2
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<dd>
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The behavior is undefined if
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<i>path
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</i>or
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<i>fd
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</i>does not refer to a terminal file.<tt> </tt>
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<dt>3
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<dd>
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If
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<i>path
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</i>or
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<i>fd
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</i>refers to a directory, the value returned applies to the
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file names within the directory.<tt> </tt>
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<dt>4
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<dd>
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The behavior is undefined if
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<i>path
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</i>or
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<i>fd
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</i>does not refer to a directory.<tt> </tt>
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<dt>5
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<dd>
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If
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<i>path
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</i>or
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<i>fd
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</i>refers to a directory, the value returned is the maximum
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length of a relative pathname when the specified directory
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is the working directory.<tt> </tt>
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<dt>6
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<dd>
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If
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<i>path
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</i>refers to a
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FIFO,
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or
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<i>fd
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</i>refers to a pipe of
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FIFO,
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the value returned applies to the referenced object itself.<tt> </tt>
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If
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<i>path
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</i>or
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<i>fd
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</i>refers to a directory, the value returned applies to any
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FIFOs
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that exist or can be created within the directory.<tt> </tt>
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If
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<i>path
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</i>or
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<i>fd
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</i>refer to any other type of file, the behavior is undefined.<tt> </tt>
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<dt>7
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<dd>
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If
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<i>path
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</i>or
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<i>fd
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</i>refer to a directory, the value returned applies
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to any files, other than directories, that
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exist or can be created within the directory.<tt> </tt>
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<dt>8
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<dd>
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The option in question is a boolean; the return value is 0 or 1.<tt> </tt>
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</dl>
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<h2>RETURN VALUES</h2>
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<p>
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On success,
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<b>pathconf()
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</b>and
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<b>fpathconf()
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</b>return
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the current
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variable value for the file or directory.<tt> </tt>
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On failure,
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they return
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-1
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and set
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<b>errno
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</b>to indicate the error.<tt> </tt>
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<p>
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If the variable corresponding to
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<i>name
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</i>has no limit for the path or file
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descriptor,
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<b>pathconf()
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</b>and
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<b>fpathconf()
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</b>return -1 without changing
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<b>errno</b>.<tt> </tt>
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<h2>ERRORS</h2>
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<p>
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<b>pathconf()
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</b>and
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<b>fpathconf()
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</b>may set
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<b>errno
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</b>to:
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<dl>
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<dt>EINVAL
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<dd>
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The value of name is invalid.<tt> </tt>
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</dl>
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<p>
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For each of the following conditions,
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if the condition is detected,
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<b>pathconf()
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</b>fails and sets
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<b>errno
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</b>to:
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<dl>
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<dt>EACCES
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<dd>
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Search permission is denied for a component of the path prefix.<tt> </tt>
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<dt>EINVAL
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<dd>
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The implementation does not support an association of the
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variable name with the specified file.<tt> </tt>
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<dt>ENAMETOOLONG
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<dd>
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The length of the path argument exceeds
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{PATH_MAX}.<tt> </tt>
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<dt><dd><p>
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A pathname component is longer than
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{NAME_MAX}
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while
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{POSIX_NO_TRUNC}
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is in effect.<tt> </tt>
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<dt>ENOENT
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<dd>
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The named file does not exist.<tt> </tt>
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<dt><dd><p>
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<i>path
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</i>points to an empty string.<tt> </tt>
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<dt>ENOTDIR
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<dd>
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A component of the path prefix is not a directory.<tt> </tt>
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</dl>
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<p>
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For each of the following conditions,
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if the condition is detected,
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<b>fpathconf()
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</b>fails and sets
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<b>errno
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</b>to:
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<dl>
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<dt>EBADF
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<dd>
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The
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<i>fd
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</i>argument is not a valid file descriptor.<tt> </tt>
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<dt>EINVAL
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<dd>
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The implementation does not support an association of the
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variable name with the specified file.<tt> </tt>
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</dl>
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<p><hr>
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Markup created by <em>unroff</em> 1.0, <tt> </tt> <tt> </tt>March 21, 1996.
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</body>
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</html>
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