.\" Copyright (c) 1989, 1991 The Regents of the University of California.
.\" %sccs.include.redist.man%
.\" @(#)fts.3 5.17 (Berkeley) %G%
.Nd traverse a file hierarchy
.Fd #include <sys/types.h>
.Fd #include <sys/stat.h>
.Fn fts_open "char * const *path_argv" "int options" "int *compar(const FTSENT *, const FTSENT *)"
.Fn fts_children "FTS *ftsp"
.Fn fts_set "FTS ftsp" "FTSENT *f" "int options"
.Fn fts_close "FTS *ftsp"
functions are provided for traversing
A simple overview is that the
function returns a ``handle'' on a file hierarchy, which is then supplied to
returns a pointer to a structure describing one of the files in the file
returns a pointer to a linked list of structures, each of which describes
one of the files contained in a directory in the hierarchy.
In general, directories are visited two distinguishable times; in pre-order
(before any of their descendants are visited) and in post-order (after all
of their descendants have been visited).
It is possible to walk the hierarchy ``logically'' (ignoring symbolic links)
or physically (visiting symbolic links), order the walk of the hierarchy or
prune and/or re-visit portions of the hierarchy.
Two structures are defined (and typedef'd) in the include file
the structure that represents the file hierarchy itself.
the structure that represents a file in the file
structure is returned for every file in the file
In this manual page, ``file'' and
.Dq Fa FTSENT No structure
structure contains at least the following fields, which are
described in greater detail below:
u_short fts_info; /* flags for FTSENT structure */
char *fts_accpath; /* access path */
char *fts_path; /* root path */
short fts_pathlen; /* strlen(fts_path) */
char *fts_name; /* file name */
short fts_namelen; /* strlen(fts_name) */
short fts_level; /* depth (\-1 to N) */
int fts_error; /* file errno */
long fts_number; /* local numeric value */
void *fts_pointer; /* local address value */
struct ftsent *fts_parent; /* parent directory */
struct ftsent *fts_link; /* next file structure */
struct ftsent *fts_cycle; /* cycle structure */
struct stat *fts_statp; /* stat(2) information */
These fields are defined as follows:
.Bl -tag -width "fts_namelen"
One of the following flags describing the returned
With the exception of directories without errors
entries are terminal, that is, they will not be revisited, nor will any
of their descendants be visited.
.Bl -tag -width FTS_DEFAULT
A directory being visited in pre-order.
A directory that causes a cycle in the tree.
structure will be filled in as well.)
structure that represents a file type not explicitly described
A directory which cannot be read.
This is an error return, and the
field will be set to indicate what caused the error.
which was not specified as a file name to
A directory being visited in post-order.
structure will be unchanged from when
it was returned in pre-order, i.e. with the
This is an error return, and the
field will be set to indicate what caused the error.
information was available.
This is an error return, and the
field will be set to indicate what caused the error.
information was requested.
A symbolic link with a non-existent target.
field reference the file characteristic information for the symbolic link
A path for accessing the file from the current directory.
The path for the file relative to the root of the traversal.
This path contains the path specified to
The length of the string referenced by
The length of the string referenced by
The depth of the traversal, numbered from \-1 to N, where this file
structure representing the parent of the starting point (or root)
of the traversal is numbered \-1, and the
field contains the value of the external variable
specifying the cause of the error.
Otherwise, the contents of the
This field is provided for the use of the application program and is
fields occupy the same physical location; using both may cause undefined
This field is provided for the use of the application program and is
fields occupy the same physical location; using both may cause undefined
structure referencing the file in the hierarchy
immediately above the current file, i.e. the directory of which this
A parent structure for the initial entry point is provided as well,
fields are guaranteed to be initialized.
field points to the next structure in the NULL-terminated linked list of
Otherwise, the contents of the
If a directory causes a cycle in the hierarchy (see
of a hard link between two directories, or a symbolic link pointing to a
field of the structure will point to the
structure in the hierarchy that references the same file as the current
Otherwise, the contents of the
information for the file.
A single buffer is used for all of the paths of all of the files in the
fields are guaranteed to be
for the file most recently returned by
To use these fields to reference any files represented by other
structures will require that the path buffer be modified using the
information contained in that
Any such modifications should be undone before further calls to
function takes a pointer to an array of character pointers naming one
or more paths which make up a logical file hierarchy to be traversed.
The array must be terminated by a
a number of options, at least one of which (either
The options are selected by
.Bl -tag -width "FTS_PHYSICAL"
structures for the targets of symbolic links
instead of the symbolic links themselves.
If this option is set, the only symbolic links for which
are returned to the application are those referencing non-existent files.
As a performance optimization, the
functions change directories as they walk the file hierarchy.
This has the side-effect that an application cannot rely on being
in any particular directory during the traversal.
option turns off this optimization, and the
functions will not change the current directory.
Note that applications should not themselves change their current directory
and try to access files unless
is specified and absolute
pathnames were provided as arguments to
structures reference file characteristic information (the
field) for each file visited.
This option relaxes that requirement as a performance optimization,
and leave the contents of the
structures for symbolic links themselves instead
of the target files they point to.
structures for all symbolic links in the
hierarchy are returned to the application.
By default, unless they are specified as path arguments to
encountered in the file hierarchy are ignored.
from descending into directories that have a different device number
than the file from which the descent began.
specifies a user-defined function which may be used to order the traversal
takes two pointers to pointers to
structures as arguments and
should return a negative value, zero, or a positive value to indicate
if the file referenced by its first argument comes before, in any order
with respect to, or after, the file referenced by its second argument.
be used in this comparison.
the directory traversal order is unspecified except
for the root paths which are traversed in the order listed in
function returns a pointer to an
structure describing a file in
Directories (that are readable and do not cause cycles) are visited at
least twice, once in pre-order and once in post-order.
All other files are visited at least once.
(Hard links between directories that do not cause cycles or symbolic
links to symbolic links may cause files to be visited more than once,
or directories more than twice.)
If all the members of the hierarchy have been returned,
and sets the external variable
If an error unrelated to a file in the hierarchy occurs,
If an error related to a returned file occurs, a pointer to an
structure is returned, and
may or may not have been set (see
may be overwritten after a call to
on the same file hierarchy stream, or, after a call to
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
structure has been returned by the function
function returns a pointer to an
structure describing the first entry in a NULL-terminated linked list of
the files in the directory represented by the
structure most recently returned by
The list is linked through the
structure, and is ordered by the user-specified comparison function, if any.
will recreate this linked list.
has not yet been called for a hierarchy,
will return a pointer to the files in the logical directory specified to
i.e. the arguments specified to
structure most recently returned by
is not a directory being visited in pre-order,
or the directory does not contain any files,
may be overwritten after a call to
on the same file hierarchy stream.
allows the user application to determine further processing for the
returns 0 on success, and \-1 if an error occurs.
must be set to one of the following values:
.Bl -tag -width FTS_PHYSICAL
Re-visit the file; any file type may be re-visited.
will return the referenced file.
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
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
The referenced file must be a symbolic link.
If the referenced file is the one most recently returned by
returns the file with the
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
fields of the structure, when returned by
will reflect the target of the symbolic link instead of the symbolic link
In either case, if the target of the symbolic link does not exist the
fields of the returned structure will be unchanged and the
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,
No descendants of this file are visited.
The file may be one of those most recently returned by either
function closes a file hierarchy stream
and restores the current directory to the directory from which
returns 0 on success, and \-1 if an error occurs.
may fail and set errno for any of the errors specified for the library
may fail and set errno for any of the errors specified for the library
may fail and set errno for any of the errors specified for the library
utility is expected to be a superset of the