797 lines
19 KiB
Groff
797 lines
19 KiB
Groff
.\" Copyright (c) 1989, 1991, 1993, 1994
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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. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgement:
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.\" This product includes software developed by the University of
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.\" California, Berkeley and its contributors.
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.\" 4. 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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.\" @(#)fts.3 8.5 (Berkeley) 4/16/94
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.\" $FreeBSD$
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.\"
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.Dd September 15, 2002
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.Dt FTS 3
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.Os
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.Sh NAME
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.Nm fts
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.Nd traverse a file hierarchy
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.Sh LIBRARY
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.Lb libc
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.Sh SYNOPSIS
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.In sys/types.h
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.In sys/stat.h
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.In fts.h
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.Ft FTS *
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.Fn fts_open "char * const *path_argv" "int options" "int (*compar)(const FTSENT **, const FTSENT **)"
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.Ft FTSENT *
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.Fn fts_read "FTS *ftsp"
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.Ft FTSENT *
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.Fn fts_children "FTS *ftsp" "int options"
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.Ft int
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.Fn fts_set "FTS *ftsp" "FTSENT *f" "int options"
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.Ft void
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.Fn fts_set_clientptr "FTS *ftsp" "void *clientdata"
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.Ft void *
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.Fn fts_get_clientptr "FTS *ftsp"
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.Ft FTS *
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.Fn fts_get_stream "FTSENT *f"
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.Ft int
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.Fn fts_close "FTS *ftsp"
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.Sh DESCRIPTION
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The
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.Nm
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functions are provided for traversing
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.Ux
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file hierarchies.
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A simple overview is that the
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.Fn fts_open
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function returns a
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.Dq handle
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on a file hierarchy, which is then supplied to
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the other
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.Nm
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functions.
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The function
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.Fn fts_read
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returns a pointer to a structure describing one of the files in the file
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hierarchy.
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The function
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.Fn fts_children
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returns a pointer to a linked list of structures, each of which describes
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one of the files contained in a directory in the hierarchy.
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In general, directories are visited two distinguishable times; in pre-order
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(before any of their descendants are visited) and in post-order (after all
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of their descendants have been visited).
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Files are visited once.
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It is possible to walk the hierarchy
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.Dq logically
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(ignoring symbolic links)
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or physically (visiting symbolic links), order the walk of the hierarchy or
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prune and/or re-visit portions of the hierarchy.
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.Pp
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Two structures are defined (and typedef'd) in the include file
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.Aq Pa fts.h .
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The first is
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.Fa FTS ,
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the structure that represents the file hierarchy itself.
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The second is
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.Fa FTSENT ,
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the structure that represents a file in the file
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hierarchy.
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Normally, an
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.Fa FTSENT
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structure is returned for every file in the file
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hierarchy.
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In this manual page,
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.Dq file
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and
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.Dq Fa FTSENT No structure
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are generally
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interchangeable.
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.Pp
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The
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.Fa FTS
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structure contains space for a single pointer, which may be used to
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store application data or per-hierarchy state.
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The
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.Fn fts_set_clientptr
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and
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.Fn fts_get_clientptr
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functions may be used to set and retrieve this pointer.
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This is likely to be useful only when accessed from the sort
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comparison function, which can determine the original
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.Fa FTS
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stream of its arguments using the
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.Fn fts_get_stream
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function.
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The two
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.Li get
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functions are also available as macros of the same name.
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.Pp
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The
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.Fa FTSENT
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structure contains at least the following fields, which are
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described in greater detail below:
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.Bd -literal
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typedef struct _ftsent {
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u_short fts_info; /* flags for FTSENT structure */
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char *fts_accpath; /* access path */
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char *fts_path; /* root path */
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u_short fts_pathlen; /* strlen(fts_path) */
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char *fts_name; /* file name */
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u_short fts_namelen; /* strlen(fts_name) */
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short fts_level; /* depth (\-1 to N) */
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int fts_errno; /* file errno */
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long fts_number; /* local numeric value */
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void *fts_pointer; /* local address value */
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struct ftsent *fts_parent; /* parent directory */
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struct ftsent *fts_link; /* next file structure */
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struct ftsent *fts_cycle; /* cycle structure */
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struct stat *fts_statp; /* stat(2) information */
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} FTSENT;
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.Ed
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.Pp
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These fields are defined as follows:
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.Bl -tag -width "fts_namelen"
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.It Fa fts_info
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One of the following values describing the returned
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.Fa FTSENT
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structure and
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the file it represents.
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With the exception of directories without errors
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.Pq Dv FTS_D ,
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all of these
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entries are terminal, that is, they will not be revisited, nor will any
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of their descendants be visited.
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.Bl -tag -width FTS_DEFAULT
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.It Dv FTS_D
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A directory being visited in pre-order.
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.It Dv FTS_DC
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A directory that causes a cycle in the tree.
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(The
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.Fa fts_cycle
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field of the
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.Fa FTSENT
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structure will be filled in as well.)
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.It Dv FTS_DEFAULT
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Any
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.Fa FTSENT
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structure that represents a file type not explicitly described
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by one of the other
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.Fa fts_info
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values.
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.It Dv FTS_DNR
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A directory which cannot be read.
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This is an error return, and the
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.Fa fts_errno
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field will be set to indicate what caused the error.
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.It Dv FTS_DOT
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A file named
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.Ql .\&
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or
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.Ql ..\&
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which was not specified as a file name to
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.Fn fts_open
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(see
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.Dv FTS_SEEDOT ) .
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.It Dv FTS_DP
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A directory being visited in post-order.
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The contents of the
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.Fa FTSENT
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structure will be unchanged from when
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it was returned in pre-order, i.e. with the
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.Fa fts_info
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field set to
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.Dv FTS_D .
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.It Dv FTS_ERR
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This is an error return, and the
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.Fa fts_errno
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field will be set to indicate what caused the error.
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.It Dv FTS_F
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A regular file.
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.It Dv FTS_NS
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A file for which no
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.Xr stat 2
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information was available.
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The contents of the
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.Fa fts_statp
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field are undefined.
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This is an error return, and the
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.Fa fts_errno
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field will be set to indicate what caused the error.
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.It Dv FTS_NSOK
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A file for which no
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.Xr stat 2
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information was requested.
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The contents of the
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.Fa fts_statp
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field are undefined.
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.It Dv FTS_SL
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A symbolic link.
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.It Dv FTS_SLNONE
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A symbolic link with a non-existent target.
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The contents of the
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.Fa fts_statp
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field reference the file characteristic information for the symbolic link
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itself.
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.El
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.It Fa fts_accpath
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A path for accessing the file from the current directory.
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.It Fa fts_path
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The path for the file relative to the root of the traversal.
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This path contains the path specified to
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.Fn fts_open
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as a prefix.
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.It Fa fts_pathlen
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The length of the string referenced by
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.Fa fts_path .
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.It Fa fts_name
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The name of the file.
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.It Fa fts_namelen
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The length of the string referenced by
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.Fa fts_name .
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.It Fa fts_level
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The depth of the traversal, numbered from \-1 to N, where this file
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was found.
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The
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.Fa FTSENT
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structure representing the parent of the starting point (or root)
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of the traversal is numbered
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.Dv FTS_ROOTPARENTLEVEL
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(\-1), and the
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.Fa FTSENT
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structure for the root
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itself is numbered
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.Dv FTS_ROOTLEVEL
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(0).
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.It Fa fts_errno
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Upon return of a
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.Fa FTSENT
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structure from the
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.Fn fts_children
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or
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.Fn fts_read
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functions, with its
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.Fa fts_info
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field set to
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.Dv FTS_DNR ,
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.Dv FTS_ERR
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or
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.Dv FTS_NS ,
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the
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.Fa fts_errno
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field contains the value of the external variable
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.Va errno
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specifying the cause of the error.
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Otherwise, the contents of the
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.Fa fts_errno
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field are undefined.
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.It Fa fts_number
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This field is provided for the use of the application program and is
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not modified by the
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.Nm
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functions.
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It is initialized to 0.
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.It Fa fts_pointer
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This field is provided for the use of the application program and is
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not modified by the
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.Nm
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functions.
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It is initialized to
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.Dv NULL .
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.It Fa fts_parent
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A pointer to the
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.Fa FTSENT
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structure referencing the file in the hierarchy
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immediately above the current file, i.e. the directory of which this
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file is a member.
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A parent structure for the initial entry point is provided as well,
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however, only the
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.Fa fts_level ,
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.Fa fts_number
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and
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.Fa fts_pointer
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fields are guaranteed to be initialized.
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.It Fa fts_link
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Upon return from the
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.Fn fts_children
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function, the
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.Fa fts_link
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field points to the next structure in the NULL-terminated linked list of
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directory members.
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Otherwise, the contents of the
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.Fa fts_link
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field are undefined.
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.It Fa fts_cycle
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If a directory causes a cycle in the hierarchy (see
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.Dv FTS_DC ) ,
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either because
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of a hard link between two directories, or a symbolic link pointing to a
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directory, the
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.Fa fts_cycle
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field of the structure will point to the
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.Fa FTSENT
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structure in the hierarchy that references the same file as the current
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.Fa FTSENT
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structure.
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Otherwise, the contents of the
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.Fa fts_cycle
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field are undefined.
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.It Fa fts_statp
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A pointer to
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.Xr stat 2
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information for the file.
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.El
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.Pp
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A single buffer is used for all of the paths of all of the files in the
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file hierarchy.
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Therefore, the
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.Fa fts_path
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and
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.Fa fts_accpath
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fields are guaranteed to be
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.Dv NUL Ns -terminated
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.Em only
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for the file most recently returned by
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.Fn fts_read .
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To use these fields to reference any files represented by other
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.Fa FTSENT
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structures will require that the path buffer be modified using the
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information contained in that
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.Fa FTSENT
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structure's
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.Fa fts_pathlen
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field.
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Any such modifications should be undone before further calls to
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.Fn fts_read
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are attempted.
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The
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.Fa fts_name
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field is always
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.Dv NUL Ns -terminated .
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.Sh FTS_OPEN
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The
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.Fn fts_open
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function takes a pointer to an array of character pointers naming one
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or more paths which make up a logical file hierarchy to be traversed.
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The array must be terminated by a
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.Dv NULL
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pointer.
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.Pp
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There are
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a number of options, at least one of which (either
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.Dv FTS_LOGICAL
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or
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.Dv FTS_PHYSICAL )
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must be specified.
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The options are selected by
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.Em or Ns 'ing
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the following values:
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.Bl -tag -width "FTS_PHYSICAL"
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.It Dv FTS_COMFOLLOW
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This option causes any symbolic link specified as a root path to be
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followed immediately whether or not
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.Dv FTS_LOGICAL
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is also specified.
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.It Dv FTS_LOGICAL
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This option causes the
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.Nm
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routines to return
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.Fa FTSENT
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structures for the targets of symbolic links
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instead of the symbolic links themselves.
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If this option is set, the only symbolic links for which
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.Fa FTSENT
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structures
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are returned to the application are those referencing non-existent files.
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Either
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.Dv FTS_LOGICAL
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or
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.Dv FTS_PHYSICAL
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.Em must
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be provided to the
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.Fn fts_open
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function.
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.It Dv FTS_NOCHDIR
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As a performance optimization, the
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.Nm
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functions change directories as they walk the file hierarchy.
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This has the side-effect that an application cannot rely on being
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in any particular directory during the traversal.
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The
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.Dv FTS_NOCHDIR
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option turns off this optimization, and the
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.Nm
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functions will not change the current directory.
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Note that applications should not themselves change their current directory
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and try to access files unless
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.Dv FTS_NOCHDIR
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is specified and absolute
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pathnames were provided as arguments to
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.Fn fts_open .
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.It Dv FTS_NOSTAT
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By default, returned
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.Fa FTSENT
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structures reference file characteristic information (the
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.Fa statp
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field) for each file visited.
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This option relaxes that requirement as a performance optimization,
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allowing the
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.Nm
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functions to set the
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.Fa fts_info
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field to
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.Dv FTS_NSOK
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and leave the contents of the
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.Fa statp
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field undefined.
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.It Dv FTS_PHYSICAL
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This option causes the
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.Nm
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routines to return
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.Fa FTSENT
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structures for symbolic links themselves instead
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of the target files they point to.
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If this option is set,
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.Fa FTSENT
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structures for all symbolic links in the
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hierarchy are returned to the application.
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Either
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.Dv FTS_LOGICAL
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or
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.Dv FTS_PHYSICAL
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.Em must
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be provided to the
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.Fn fts_open
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function.
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.It Dv FTS_SEEDOT
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By default, unless they are specified as path arguments to
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.Fn fts_open ,
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any files named
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.Ql .\&
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or
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.Ql ..\&
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encountered in the file hierarchy are ignored.
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This option causes the
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.Nm
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routines to return
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.Fa FTSENT
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structures for them.
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.It Dv FTS_XDEV
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This option prevents
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.Nm
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from descending into directories that have a different device number
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than the file from which the descent began.
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.El
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.Pp
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The argument
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.Fn compar
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specifies a user-defined function which may be used to order the traversal
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of the hierarchy.
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It
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takes two pointers to pointers to
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.Fa FTSENT
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structures as arguments and
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should return a negative value, zero, or a positive value to indicate
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if the file referenced by its first argument comes before, in any order
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with respect to, or after, the file referenced by its second argument.
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The
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.Fa fts_accpath ,
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.Fa fts_path
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and
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.Fa fts_pathlen
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fields of the
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.Fa FTSENT
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structures may
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.Em never
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be used in this comparison.
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If the
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.Fa fts_info
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field is set to
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.Dv FTS_NS
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or
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.Dv FTS_NSOK ,
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the
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.Fa fts_statp
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field may not either.
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If the
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.Fn compar
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argument is
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.Dv NULL ,
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the directory traversal order is in the order listed in
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.Fa path_argv
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for the root paths, and in the order listed in the directory for
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everything else.
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.Sh FTS_READ
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|
The
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.Fn fts_read
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function returns a pointer to an
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.Fa FTSENT
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structure describing a file in
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the hierarchy.
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Directories (that are readable and do not cause cycles) are visited at
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least twice, once in pre-order and once in post-order.
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All other files are visited at least once.
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(Hard links between directories that do not cause cycles or symbolic
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links to symbolic links may cause files to be visited more than once,
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or directories more than twice.)
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.Pp
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|
If all the members of the hierarchy have been returned,
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.Fn fts_read
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returns
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.Dv NULL
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and sets the external variable
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.Va errno
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to 0.
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If an error unrelated to a file in the hierarchy occurs,
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.Fn fts_read
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returns
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.Dv NULL
|
|
and sets
|
|
.Va errno
|
|
appropriately.
|
|
If an error related to a returned file occurs, a pointer to an
|
|
.Fa FTSENT
|
|
structure is returned, and
|
|
.Va errno
|
|
may or may not have been set (see
|
|
.Fa fts_info ) .
|
|
.Pp
|
|
The
|
|
.Fa FTSENT
|
|
structures returned by
|
|
.Fn fts_read
|
|
may be overwritten after a call to
|
|
.Fn fts_close
|
|
on the same file hierarchy stream, or, after a call to
|
|
.Fn fts_read
|
|
on the same file hierarchy stream unless they represent a file of type
|
|
directory, in which case they will not be overwritten until after a call to
|
|
.Fn fts_read
|
|
after the
|
|
.Fa FTSENT
|
|
structure has been returned by the function
|
|
.Fn fts_read
|
|
in post-order.
|
|
.Sh FTS_CHILDREN
|
|
The
|
|
.Fn fts_children
|
|
function returns a pointer to an
|
|
.Fa FTSENT
|
|
structure describing the first entry in a NULL-terminated linked list of
|
|
the files in the directory represented by the
|
|
.Fa FTSENT
|
|
structure most recently returned by
|
|
.Fn fts_read .
|
|
The list is linked through the
|
|
.Fa fts_link
|
|
field of the
|
|
.Fa FTSENT
|
|
structure, and is ordered by the user-specified comparison function, if any.
|
|
Repeated calls to
|
|
.Fn fts_children
|
|
will recreate this linked list.
|
|
.Pp
|
|
As a special case, if
|
|
.Fn fts_read
|
|
has not yet been called for a hierarchy,
|
|
.Fn fts_children
|
|
will return a pointer to the files in the logical directory specified to
|
|
.Fn fts_open ,
|
|
i.e. the arguments specified to
|
|
.Fn fts_open .
|
|
Otherwise, if the
|
|
.Fa FTSENT
|
|
structure most recently returned by
|
|
.Fn fts_read
|
|
is not a directory being visited in pre-order,
|
|
or the directory does not contain any files,
|
|
.Fn fts_children
|
|
returns
|
|
.Dv NULL
|
|
and sets
|
|
.Va errno
|
|
to zero.
|
|
If an error occurs,
|
|
.Fn fts_children
|
|
returns
|
|
.Dv NULL
|
|
and sets
|
|
.Va errno
|
|
appropriately.
|
|
.Pp
|
|
The
|
|
.Fa FTSENT
|
|
structures returned by
|
|
.Fn fts_children
|
|
may be overwritten after a call to
|
|
.Fn fts_children ,
|
|
.Fn fts_close
|
|
or
|
|
.Fn fts_read
|
|
on the same file hierarchy stream.
|
|
.Pp
|
|
.Em Option
|
|
may be set to the following value:
|
|
.Bl -tag -width FTS_NAMEONLY
|
|
.It Dv FTS_NAMEONLY
|
|
Only the names of the files are needed.
|
|
The contents of all the fields in the returned linked list of structures
|
|
are undefined with the exception of the
|
|
.Fa fts_name
|
|
and
|
|
.Fa fts_namelen
|
|
fields.
|
|
.El
|
|
.Sh FTS_SET
|
|
The function
|
|
.Fn fts_set
|
|
allows the user application to determine further processing for the
|
|
file
|
|
.Fa f
|
|
of the stream
|
|
.Fa ftsp .
|
|
The
|
|
.Fn fts_set
|
|
function
|
|
returns 0 on success, and \-1 if an error occurs.
|
|
.Em Option
|
|
must be set to one of the following values:
|
|
.Bl -tag -width FTS_PHYSICAL
|
|
.It Dv FTS_AGAIN
|
|
Re-visit the file; any file type may be re-visited.
|
|
The next call to
|
|
.Fn fts_read
|
|
will return the referenced file.
|
|
The
|
|
.Fa fts_stat
|
|
and
|
|
.Fa fts_info
|
|
fields of the structure will be reinitialized at that time,
|
|
but no other fields will have been changed.
|
|
This option is meaningful only for the most recently returned
|
|
file from
|
|
.Fn fts_read .
|
|
Normal use is for post-order directory visits, where it causes the
|
|
directory to be re-visited (in both pre and post-order) as well as all
|
|
of its descendants.
|
|
.It Dv FTS_FOLLOW
|
|
The referenced file must be a symbolic link.
|
|
If the referenced file is the one most recently returned by
|
|
.Fn fts_read ,
|
|
the next call to
|
|
.Fn fts_read
|
|
returns the file with the
|
|
.Fa fts_info
|
|
and
|
|
.Fa fts_statp
|
|
fields reinitialized to reflect the target of the symbolic link instead
|
|
of the symbolic link itself.
|
|
If the file is one of those most recently returned by
|
|
.Fn fts_children ,
|
|
the
|
|
.Fa fts_info
|
|
and
|
|
.Fa fts_statp
|
|
fields of the structure, when returned by
|
|
.Fn fts_read ,
|
|
will reflect the target of the symbolic link instead of the symbolic link
|
|
itself.
|
|
In either case, if the target of the symbolic link does not exist the
|
|
fields of the returned structure will be unchanged and the
|
|
.Fa fts_info
|
|
field will be set to
|
|
.Dv FTS_SLNONE .
|
|
.Pp
|
|
If the target of the link is a directory, the pre-order return, followed
|
|
by the return of all of its descendants, followed by a post-order return,
|
|
is done.
|
|
.It Dv FTS_SKIP
|
|
No descendants of this file are visited.
|
|
The file may be one of those most recently returned by either
|
|
.Fn fts_children
|
|
or
|
|
.Fn fts_read .
|
|
.El
|
|
.Sh FTS_CLOSE
|
|
The
|
|
.Fn fts_close
|
|
function closes a file hierarchy stream
|
|
.Fa ftsp
|
|
and restores the current directory to the directory from which
|
|
.Fn fts_open
|
|
was called to open
|
|
.Fa ftsp .
|
|
The
|
|
.Fn fts_close
|
|
function
|
|
returns 0 on success, and \-1 if an error occurs.
|
|
.Sh ERRORS
|
|
The function
|
|
.Fn fts_open
|
|
may fail and set
|
|
.Va errno
|
|
for any of the errors specified for the library functions
|
|
.Xr open 2
|
|
and
|
|
.Xr malloc 3 .
|
|
.Pp
|
|
The function
|
|
.Fn fts_close
|
|
may fail and set
|
|
.Va errno
|
|
for any of the errors specified for the library functions
|
|
.Xr chdir 2
|
|
and
|
|
.Xr close 2 .
|
|
.Pp
|
|
The functions
|
|
.Fn fts_read
|
|
and
|
|
.Fn fts_children
|
|
may fail and set
|
|
.Va errno
|
|
for any of the errors specified for the library functions
|
|
.Xr chdir 2 ,
|
|
.Xr malloc 3 ,
|
|
.Xr opendir 3 ,
|
|
.Xr readdir 3
|
|
and
|
|
.Xr stat 2 .
|
|
.Pp
|
|
In addition,
|
|
.Fn fts_children ,
|
|
.Fn fts_open
|
|
and
|
|
.Fn fts_set
|
|
may fail and set
|
|
.Va errno
|
|
as follows:
|
|
.Bl -tag -width Er
|
|
.It Bq Er EINVAL
|
|
The options were invalid.
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr find 1 ,
|
|
.Xr chdir 2 ,
|
|
.Xr stat 2 ,
|
|
.Xr qsort 3
|
|
.Sh HISTORY
|
|
The
|
|
.Nm
|
|
interface was first introduced in
|
|
.Bx 4.4 .
|
|
The
|
|
.Fn fts_get_clientptr ,
|
|
.Fn fts_get_stream ,
|
|
and
|
|
.Fn fts_set_clientptr
|
|
functions were introduced in
|
|
.Fx 5.0 ,
|
|
principally to provide for alternative interfaces to the
|
|
.Nm
|
|
functionality using different data structures.
|