7e6cabd06e
Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann <jschauma@stevens.edu> Pull Request: https://github.com/freebsd/freebsd/pull/96
262 lines
7.5 KiB
Groff
262 lines
7.5 KiB
Groff
.\" Copyright (c) 1993
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.\" The Regents of the University of California. All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\" 3. Neither the name of the University nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" @(#)pathconf.2 8.1 (Berkeley) 6/4/93
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.\" $FreeBSD$
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.\"
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.Dd July 7, 2009
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.Dt PATHCONF 2
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.Os
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.Sh NAME
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.Nm pathconf ,
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.Nm lpathconf ,
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.Nm fpathconf
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.Nd get configurable pathname variables
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In unistd.h
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.Ft long
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.Fn pathconf "const char *path" "int name"
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.Ft long
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.Fn lpathconf "const char *path" "int name"
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.Ft long
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.Fn fpathconf "int fd" "int name"
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.Sh DESCRIPTION
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The
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.Fn pathconf ,
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.Fn lpathconf
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and
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.Fn fpathconf
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system calls provide a method for applications to determine the current
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value of a configurable system limit or option variable associated
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with a pathname or file descriptor.
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.Pp
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For
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.Fn pathconf
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and
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.Fn lpathconf ,
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the
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.Fa path
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argument is the name of a file or directory.
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For
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.Fn fpathconf ,
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the
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.Fa fd
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argument is an open file descriptor.
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The
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.Fa name
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argument specifies the system variable to be queried.
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Symbolic constants for each name value are found in the include file
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.Li <unistd.h> .
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.Pp
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The
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.Fn lpathconf
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system call is like
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.Fn pathconf
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except in the case where the named file is a symbolic link,
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in which case
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.Fn lpathconf
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returns information about the link,
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while
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.Fn pathconf
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returns information about the file the link references.
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.Pp
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The available values are as follows:
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.Bl -tag -width 6n
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.It Li _PC_LINK_MAX
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The maximum file link count.
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.It Li _PC_MAX_CANON
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The maximum number of bytes in terminal canonical input line.
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.It Li _PC_MAX_INPUT
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The minimum maximum number of bytes for which space is available in
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a terminal input queue.
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.It Li _PC_NAME_MAX
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The maximum number of bytes in a file name.
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.It Li _PC_PATH_MAX
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The maximum number of bytes in a pathname.
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.It Li _PC_PIPE_BUF
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The maximum number of bytes which will be written atomically to a pipe.
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.It Li _PC_CHOWN_RESTRICTED
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Return 1 if appropriate privilege is required for the
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.Xr chown 2
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system call, otherwise 0.
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.St -p1003.1-2001
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requires appropriate privilege in all cases, but this behavior was optional
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in prior editions of the standard.
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.It Li _PC_NO_TRUNC
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Return greater than zero if attempts to use pathname components longer than
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.Brq Dv NAME_MAX
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will result in an
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.Bq Er ENAMETOOLONG
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error; otherwise, such components will be truncated to
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.Brq Dv NAME_MAX .
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.St -p1003.1-2001
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requires the error in all cases, but this behavior was optional in prior
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editions of the standard, and some
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.No non- Ns Tn POSIX Ns -compliant
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file systems do not support this behavior.
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.It Li _PC_VDISABLE
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Returns the terminal character disabling value.
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.It Li _PC_ASYNC_IO
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Return 1 if asynchronous I/O is supported, otherwise 0.
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.It Li _PC_PRIO_IO
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Returns 1 if prioritised I/O is supported for this file,
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otherwise 0.
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.It Li _PC_SYNC_IO
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Returns 1 if synchronised I/O is supported for this file, otherwise 0.
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.It Li _PC_ALLOC_SIZE_MIN
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Minimum number of bytes of storage allocated for any portion of a file.
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.It Li _PC_FILESIZEBITS
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Number of bits needed to represent the maximum file size.
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.It Li _PC_REC_INCR_XFER_SIZE
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Recommended increment for file transfer sizes between
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.Dv _PC_REC_MIN_XFER_SIZE
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and
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.Dv _PC_REC_MAX_XFER_SIZE .
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.It Li _PC_REC_MAX_XFER_SIZE
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Maximum recommended file transfer size.
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.It Li _PC_REC_MIN_XFER_SIZE
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Minimum recommended file transfer size.
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.It Li _PC_REC_XFER_ALIGN
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Recommended file transfer buffer alignment.
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.It Li _PC_SYMLINK_MAX
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Maximum number of bytes in a symbolic link.
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.It Li _PC_ACL_EXTENDED
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Returns 1 if an Access Control List (ACL) can be set on the specified
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file, otherwise 0.
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.It Li _PC_ACL_NFS4
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Returns 1 if an NFSv4 ACLs can be set on the specified
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file, otherwise 0.
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.It Li _PC_ACL_PATH_MAX
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Maximum number of ACL entries per file.
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.It Li _PC_CAP_PRESENT
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Returns 1 if a capability state can be set on the specified file,
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otherwise 0.
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.It Li _PC_INF_PRESENT
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Returns 1 if an information label can be set on the specified file,
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otherwise 0.
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.It Li _PC_MAC_PRESENT
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Returns 1 if a Mandatory Access Control (MAC) label can be set on the
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specified file, otherwise 0.
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.It Li _PC_MIN_HOLE_SIZE
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If a file system supports the reporting of holes (see
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.Xr lseek 2 ) ,
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.Fn pathconf
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and
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.Fn fpathconf
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return a positive number that represents the minimum hole size returned in
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bytes.
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The offsets of holes returned will be aligned to this same value.
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A special value of 1 is returned if the file system does not specify the minimum
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hole size but still reports holes.
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.El
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.Sh RETURN VALUES
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If the call to
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.Fn pathconf
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or
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.Fn fpathconf
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is not successful, \-1 is returned and
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.Va errno
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is set appropriately.
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Otherwise, if the variable is associated with functionality that does
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not have a limit in the system, \-1 is returned and
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.Va errno
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is not modified.
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Otherwise, the current variable value is returned.
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.Sh ERRORS
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If any of the following conditions occur, the
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.Fn pathconf
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and
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.Fn fpathconf
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system calls shall return -1 and set
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.Va errno
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to the corresponding value.
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.Bl -tag -width Er
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.It Bq Er EINVAL
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The value of the
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.Fa name
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argument is invalid.
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.It Bq Er EINVAL
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The implementation does not support an association of the variable
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name with the associated file.
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.El
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.Pp
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The
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.Fn pathconf
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system call
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will fail if:
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.Bl -tag -width Er
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.It Bq Er ENOTDIR
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A component of the path prefix is not a directory.
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.It Bq Er ENAMETOOLONG
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A component of a pathname exceeded
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.Brq Dv NAME_MAX
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characters (but see
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.Dv _PC_NO_TRUNC
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above),
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or an entire path name exceeded
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.Brq Dv PATH_MAX
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characters.
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.It Bq Er ENOENT
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The named file does not exist.
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.It Bq Er EACCES
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Search permission is denied for a component of the path prefix.
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.It Bq Er ELOOP
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Too many symbolic links were encountered in translating the pathname.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.El
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.Pp
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The
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.Fn fpathconf
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system call
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will fail if:
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.Bl -tag -width Er
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.It Bq Er EBADF
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The
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.Fa fd
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argument
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is not a valid open file descriptor.
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.It Bq Er EIO
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An I/O error occurred while reading from or writing to the file system.
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.El
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.Sh SEE ALSO
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.Xr lseek 2 ,
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.Xr sysctl 3
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.Sh HISTORY
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The
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.Fn pathconf
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and
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.Fn fpathconf
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system calls first appeared in
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.Bx 4.4 .
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The
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.Fn lpathconf
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system call first appeared in
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.Fx 8.0 .
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