cs-fstags 20250528
Simple filesystem based file tagging and the associated `fstags` command line tool.
Keywords: python3

Simple filesystem based file tagging
and the associated `fstags` command line tool.

*Latest release 20250528*:
* New TaggedPathSet implementing a set of TaggedPaths.
* FSTags.mv: link then remove to avoid tromping dstpath.

Many basic tasks can be performed with the `fstags` command line utility,
documented under the `FSTagsCommand` class below.

Why `fstags`?
By storing the tags in a separate file we:
* can store tags without modifying a file
* do not need to know the file's format,
  or even whether that format supports metadata
* can process tags on any kind of file
* because tags are inherited from parent directories,
  tags can be automatically acquired merely by arranging your file tree

Tags are stored in the file `.fstags` in each directory;
there is a line for each entry in the directory
consisting of the directory entry name and its associated tags.

Programmatically one creates an `FSTags` instance and accesses
the `TagSet`s for whichever filesystem paths are of interest:

    with FSTags() as fstags:
        tagged = fstags['/path/to/some/file']
        tagged['foo']=9 # set the tag foo=9

In a `.fstags` tag file tags may be "bare", or have a value.
If there is a value it is expressed with an equals (`'='`)
followed by the JSON encoding of the value.

The inherited tags for a file are the union of its direct tags
and all relevant ancestor tags,
with priority given to tags closer to the file.

For example, a media file for a television episode with the pathname
`/path/to/series-name/season-02/episode-name--s02e03--something.mp4`
might have the tags:

    series_title="Series Full Name"
    season=2
    sf
    episode=3
    episode_title="Full Episode Title"

obtained from the following `.fstags` entries:
* tag file `/path/to/.fstags`:

      series-name sf series_title="Series Full Name"

* tag file `/path/to/series-name/.fstags`:

      season-02 season=2

* tag file `/path/to/series-name/season-02/.fstags`:

      episode-name--s02e03--something.mp4 episode=3 episode_title="Full Episode Title"

## `fstags` Examples ##

### Backing up a media tree too big for the removable drives ###

Walk the media tree for files tagged for backup to `archive2`:

    fstags find /path/to/media backup=archive2

Walk the media tree for files not assigned to a backup archive:

    fstags find /path/to/media -backup

Backup the `archive2` files using `rsync`:

    fstags find --for-rsync /path/to/media backup=archive2 \
    | rsync -ia --include-from=- /path/to/media /path/to/backup_archive2

Short summary:
* `CachedValue`: Manage a cached value stored in a `TaggedPath`. The value and the validity state are stored in a prefixed subsection of the tags.
* `CascadeRule`: A cascade rule of possible source tag names to provide a target tag.
* `DEFAULT_FSTAGS`: A class to examine filesystem tags.
* `FSTags`: A class to examine filesystem tags.
* `FSTagsCommand`: Usage: {cmd} [-o ontology] [-P] subcommand [...] Work with fstags.
* `FSTagsConfig`: A configuration for fstags.
* `FSTagsTagFile`: A `FSTagsTagFile` indexing `TagSet`s for file paths which lives in the file path's directory.
* `get_xattr_value`: Read the extended attribute `xattr_name` of `fspath`. Return the extended attribute value as a string, or `None` if the attribute does not exist.
* `HasFSTagsMixin`: Mixin providing an automatic `.fstags` property.
* `is_valid_basename`: Test whether `name` is a valid basefile for something in a directory.
* `main`: Command line mode.
* `rsync_patterns`: Return a list of rsync include lines suitable for use with the `--include-from` option.
* `TaggedPath`: Class to manipulate the tags for a specific filesystem path.
* `TaggedPathSet`: A set of `TaggedPath` instances also indexed by their `Tag`s.
* `update_xattr_value`: Update the extended attributes of `fspath` with `new_xattr_value` for `xattr_name`. Return the previous value, or `None` if the attribute was missing.
* `verbose`: Emit message if in verbose mode.

Module contents:
- <a name="CachedValue"></a>`Class `CachedValue``: Manage a cached value stored in a `TaggedPath`.
  The value and the validity state are stored in a prefixed
  subsection of the tags.

  This is how modules like `cs.hashindex` cache file content hashcodes.

  The default state function is `TaggedPath.stat_size_mtime`,
  which returns `{'st_size':st_size,'st_mtime':int(st_mtime)}` by default,
  essentially the same criteria used by `rsync(1)` to skip
  comparing file contents.

  Example:

        tags = fstags[fspath]
        hash

*`CachedValue.__init__(self, taggedpath: cs.fstags.TaggedPath, prefix: str, name: str, *, state_func: Optional[Callable[[str], Mapping[str, Any]]] = None)`*:
Initialise a cached value reference.

Parameters:
* `taggedpath`: the `TaggedPath` tagged file system path
* `prefix`: the tags prefix
* `name`: the tag name for the value
* `state_func`; an optional function to compute the current
  state if `taggedpath`; the default is
  `CachedValue.stat_size_mtime` which returns the current
  file `st_size` and `st_mtime`

*`CachedValue.get(self) -> Tuple[Optional[Any], Mapping[str, Any]]`*:
Get the cached value if the current state matches the cache
state, otherwise `None`.
Return the valu or `None` and the current state.

*`CachedValue.set(self, value: Any, *, state: Mapping = None)`*:
Update the cached value and associated state.
If the state is omitted, the current state is used.

*`CachedValue.stat_size_mtime(fspath: str, round_mtime=<class 'int'>, follow_symlinks=True) -> dict`*:
Return the default cache state mapping.
This function `stat`s the `fspath` and returns `{'size':st_size,'mtime':int(st_mtime)}`.
- <a name="CascadeRule"></a>`Class `CascadeRule``: A cascade rule of possible source tag names to provide a target tag.

*`CascadeRule.infer_tag(self, tagset)`*:
Apply the rule to the `TagSet` `tagset`.
Return a new `Tag(self.target,value)`
for the first cascade `value` found in `tagset`,
or `None` if there is no match.
- <a name="DEFAULT_FSTAGS"></a>`DEFAULT_FSTAGS = FSTags('.fstags')`: A class to examine filesystem tags.
- <a name="FSTags"></a>`Class `FSTags(cs.resources.MultiOpenMixin)``: A class to examine filesystem tags.

*`FSTags.__init__(self, tagsfile_basename=None, ontology_filepath=None, physical=None, update_mapping: Optional[Mapping] = None, update_prefix: Optional[str] = 'cs.fstags', update_uuid_tag_name: Optional[str] = 'uuid')`*:
Initialise the `FSTags` instance.

Parameters:
* `tagsfile_basename`: optional basename forthe backing tags files,
  default from `TAGSFILE_BASENAME`: `'.fstags'`
* `ontology_filepath`: optional filesystem path for an associated ontology
* `physical`: optional flag for the associated `FSTagsConfig`
  specifying whether `TagFile`s are indexed by their physical or logical
  filesystem paths
* `update_mapping`: optional secondary mapping to which to mirror
  tags, such as an `SQLTags`;
  the default comes from an `SQLTags` specified by the
  environment variable `$FSTAGS_UPDATE_MAPPING`
  if present
* `update_prefix`: optional key prefix for use in the secondary mapping;
  the default comes from the environment variable
  `$FSTAGS_UPDATE_MAPPING_PREFIX` if present,
  otherwise `'cs.fstags'`
* `update_uuid_tag_name`: optional name for the per file UUID tag name;
  default `'uuid'`

*`FSTags.__getitem__(self, path, *, verbose: bool) -> 'TaggedPath'`*:
Return the `TaggedPath` for `abspath(path)`.

*`FSTags.apply_tag_choices(self, tag_choices, paths)`*:
Apply the `tag_choices` to `paths`.

Parameters:
* `tag_choices`:
  an iterable of `Tag` or an equality `TagBasedTest`.
  Each item applies or removes a `Tag`
  from each path's direct tags.
* `paths`:
  an iterable of filesystem paths.

*`FSTags.attach_path(self, attach, srcpath, dstpath, *, force=False, crop_ok=False)`*:
Attach `srcpath` to `dstpath` using the `attach` callable.

Parameters:
* `attach`: callable accepting `attach(srcpath,dstpath)`
  to do the desired attachment,
  such as a copy, link or move
* `srcpath`: the source filesystem object
* `dstpath`: the destination filesystem object
* `crop_ok`: if true and the OS raises `OSError(ENAMETOOLONG)`
  attempt to crop the name before the file extension and retry
* `force`: default `False`.
  If true and the destination exists
  try to remove it before calling `attach`.
  Otherwise if the destination exists
  raise a `ValueError`.

*`FSTags.cascade_tags(self, tags, cascade_rules=None)`*:
Yield `Tag`s
which cascade from the `TagSet` `tags`
via `cascade_rules` (an iterable of `CascadeRules`).

*`FSTags.copy(self, srcpath, dstpath, **kw)`*:
Copy `srcpath` to `dstpath`.

*`FSTags.dir_tagfile(self, dirpath: str) -> 'FSTagsTagFile'`*:
Return the `FSTagsTagFile` associated with `dirpath`.

*`FSTags.edit_dirpath(self, dirpath, all_names=False)`*:
Edit the filenames and tags in a directory.

If `all_names` is true, include names commencing with a dot,
otherwise exclude them.

*`FSTags.export_xattrs(self, paths)`*:
Import the extended attributes of `paths`
and use them to update the fstags.

*`FSTags.find(self, path, tag_tests, use_direct_tags=False)`*:
Walk the file tree from `path`
searching for files matching the supplied `tag_tests`.
Yield the matching file paths.

Parameters:
* `path`: the top of the file tree to walk
* `tag_tests`: a sequence of `TagBasedTest`s
* `use_direct_tags`: test the `direct_tags` if true,
  otherwise the `all_tags`.
  Default: `False`

*`FSTags.find_ontology(self, dirpath, ontbase=None)`*:
Locate an ontology for the directory `dirpath`.
The optional `ontbase` may override the relative path to the file,
default is `self.ontology_filepath`.
Return a `TagOntology` or `None` if not found.

*`FSTags.find_ontpath(self, dirpath, ontbase=None)`*:
Locate an ontology file for the directory `dirpath`.
The optional `ontbase` may override the relative path to the file,
default is `self.ontology_filepath`.
Return the found ontology file or `None` if not found.

*`FSTags.import_xattrs(self, paths)`*:
Update the extended attributes of `paths`
from their fstags.

*`FSTags.keypath(self, fspath)`*:
Compute the absolute path used to index a `TaggedPath` instance.

This returns `realpath(fspath)` if `self.config.physical`,
otherwise `abspath(fspath)`.

*`FSTags.link(self, srcpath, dstpath, **kw)`*:
Link `srcpath` to `dstpath`.

*`FSTags.move(self, srcpath, dstpath, **kw)`*:
Move `srcpath` to `dstpath`.

*`FSTags.mv(self, srcpath: str, dstpath: str, *, symlink=False, remove=True)`*:
Move (or link or symlink) `srcpath` to `dstpath`.
It is an error if `dstpath` already exists.
Note that a move uses a hardlink+rename and will not work across filesystems.

Parameters:
* `srcpath`: the source filesystem path
* `dstpath`: the destination filesystem path
* `symlink`: default `False`: if true, make a symbolic link
* `remove`: default `True`: if true, remove `srcpath` after
  hard linking to `dstpath`

*`FSTags.ontology`*:
The primary `TagsOntology`, or `None` if `self.ontology_filepath` was `None`.

*`FSTags.ontology_filepath`*:
The ontology file basename.

*`FSTags.ontology_for(self, path, ontbase=None)`*:
Return the `TagsOntology` associated with `path`.
Returns `None` if an ontology cannot be found.

*`FSTags.open_ontology(self, ontpath)`*:
Open the contology file at `ontpath`.

*`FSTags.path_tagfiles(self, fspath)`*:
Generator yielding a sequence of `(FSTagsTagFile,name)` pairs
where `name` is the key within the `FSTagsTagFile`
for the `FSTagsTagFile`s affecting `fspath`
in order from the root to `dirname(fspath)`.

*`FSTags.resolve_format_string(self, format_string)`*:
See if `format_string` looks like `[`*clausename*`]`*entryname*.
if so, return the corresponding config entry string,
otherwise return `format_string` unchanged.

*`FSTags.scrub(self, path)`*:
Scrub tags for names which do not exist in the filesystem.

*`FSTags.startup_shutdown(self)`*:
Sync tag files and db mapping on final close.

*`FSTags.sync(self)`*:
Flush modified tag files.

*`FSTags.tagfile_for(self, fspath)`*:
Return the `FSTagsTagFile` storing the `Tag`s for `fspath`.

*`FSTags.tagsfile_basename`*:
The tag file basename.

*`FSTags.test(self, path, tag_tests, use_direct_tags=False)`*:
Test a path against `tag_tests`.

Parameters:
* `path`: path to test
* `tag_tests`: an iterable of `TagBasedTest`s
* `use_direct_tags`: test the `direct_tags` if true,
  otherwise the `all_tags`.
  Default: `False`
- <a name="FSTagsCommand"></a>`Class `FSTagsCommand(cs.cmdutils.BaseCommand, cs.tagset.TagsCommandMixin)``: Usage: {cmd} [-o ontology] [-P] subcommand [...]
  Work with fstags.

  Usage summary:

      Usage: fstags [common-options...] [-o ontology] [-P] subcommand [...]
        Work with fstags.
        Subcommands:
          autotag [common-options...] paths...
            Tag paths based on rules from the rc file.
          cp [common-options...] [-finv] srcpath dstpath, cp [common-options...] [-finv] srcpaths... dstdirpath
            POSIX cp(1) equivalent, but also copying tags: copy files and their tags into targetdir.
            -f  Force: remove destination if it exists.
            -i  Interactive: fail if the destination exists.
            -n  No remove: fail if the destination exists.
            -v  Verbose: show copied files.
          cptags [common-options...] srcpath dstpath
            Copy the direct tags from srcpath to dstpath.
          edit [common-options...] [-ad] [path]
            Edit the direct tagsets of path, default: '.'.
            If path is a directory, provide the tags of its entries.
            Otherwise edit just the tags for path.
            -a    List all names in directory edit mode; normally
                  names commencing with a dot are omitted.
            -d    Treat directories like files: edit just its tags.
          export [common-options...] [-a] [--direct] path {tag[=value]|-tag}...
            Export tags for files from paths matching all the constraints.
            -a        Export all paths, not just those with tags.
            --direct  Export the direct tags instead of the computed tags.
            The output is in the same CSV format as that from "sqltags export",
            with the following columns:
            * unixtime: the file's st_mtime from os.stat.
            * id: empty
            * name: the file path
            * tags: the file's direct or indirect tags
          find [common-options...] [--direct] [--for-rsync] [-o output_format] path {tag[=value]|-tag}...
            List files from path matching all the constraints.
            --direct    Use direct tags instead of all tags.
            --for-rsync Instead of listing matching paths, emit a
                        sequence of rsync(1) patterns suitable for use with
                        --include-from in order to do a selective rsync of the
                        matched paths.
            -o output_format
                        Use output_format as a Python format string to lay out
                        the listing.
                        Default: {fspath}
          help [common-options...] [-l] [-s] [subcommand-names...]
            Print help for subcommands.
            This outputs the full help for the named subcommands,
            or the short help for all subcommands if no names are specified.
          import [common-options...] {-|srcpath}...
            Import CSV data in the format emitted by "export".
            Each argument is a file path or "-", indicating standard input.
          infer [common-options...] pathname
            Print the base and inferred tags for pathname.
          info [common-options...] [field-names...]
            Recite general information.
            Explicit field names may be provided to override the default listing.
          json_import --prefix=tag_prefix {-|path} {-|tags.json}
            Apply JSON data to path.
            A path named "-" indicates that paths should be read from
            the standard input.
            The JSON tag data come from the file "tags.json"; the name
            "-" indicates that the JSON data should be read from the
            standard input.
          ln [common-options...] [-finv] srcpath dstpath, ln [common-options...] [-finv] srcpaths... dstdirpath
            POSIX ln(1) equivalent, but also copying the tags: link files and their tags into targetdir.
            -f  Force: remove destination if it exists.
            -i  Interactive: fail if the destination exists.
            -n  No remove: fail if the destination exists.
            -v  Verbose: show linked files.
          ls [common-options...] [-dlr] [--direct] [-o output_format] [paths...]
            List files from paths and their tags.
            -d          Treat directories like files, do not recurse.
            --direct    List direct tags instead of all tags.
            -l          Long format.
            -o output_format
                        Use output_format as a Python format string to lay out
                        the listing.
                        Default: {fspath:json} {tags}
            -r          Recurse into subdirectories.
          mv [common-options...] [-finv] srcpath dstpath, mv [common-options...] [-finv] srcpaths... dstdirpath
            POSIX mv(1) equivalent, but also copying the tags: move files and their tags into targetdir.
            -f  Force: remove destination if it exists.
            -i  Interactive: fail if the destination exists.
            -n  No remove: fail if the destination exists.
            -v  Verbose: show moved files.
          ns [common-options...] [-d] [--direct] [paths...]
            Report on the available primary namespace fields for formatting.
            Note that because the namespace used for formatting has
            inferred field names there are also unshown secondary field
            names available in format strings.
            -d          Treat directories like files, do not recurse.
            --direct    List direct tags instead of all tags.
          ont [common-options...] [subcommand [args...]]
            With no arguments, print the ontology.
          rename [common-options...] -o basename_format paths...
            Rename paths according to a format string.
            -o basename_format
                Use basename_format as a Python format string to
                compute the new basename for each path.
          repl [common-options...]
            Run a REPL (Read Evaluate Print Loop), an interactive Python prompt.
          scrub [common-options...] paths...
            Remove all tags for missing paths.
            If a path is a directory, scrub the immediate paths in the directory.
          shell [common-options...]
            Run a command prompt via cmd.Cmd using this command's subcommands.
          tag [common-options...] {-|path} {tag[=value]|-tag}...
            Tag a path with multiple tags.
            With the form "-tag", remove that tag from the direct tags.
            A path named "-" indicates that paths should be read from the
            standard input.
          tagfile [common-options...] tagfile_path [subcommand ...]
            Perform operations on a tag file.
            Subcommands:
              tag tagset_name {tag[=value]|-tag}...
                Directly modify tag_name within the tag file tagfile_path.
          tagpaths [common-options...] {tag[=value]|-tag} {-|paths...}
            Tag multiple paths.
            With the form "-tag", remove the tag from the immediate tags.
            A single path named "-" indicates that paths should be read
            from the standard input.
          test [common-options...] [--direct] path {tag[=value]|-tag}...
            Test whether the path matches all the constraints.
            --direct    Use direct tags instead of all tags.
          xattr-export [common-options...] {-|paths...}
            Import tag information from extended attributes.
          xattr-import [common-options...] {-|paths...}
            Update extended attributes from tags.

*`FSTagsCommand.Options`*

*`FSTagsCommand.cmd_autotag(self, argv, *, upd: cs.upd.Upd, runstate: Optional[cs.resources.RunState] = <function uses_runstate.<locals>.<lambda> at 0x108790680>)`*:
Usage: {cmd} paths...
Tag paths based on rules from the rc file.

*`FSTagsCommand.cmd_cp(self, argv)`*:
Usage: {cmd} [-finv] srcpath dstpath, {cmd} [-finv] srcpaths... dstdirpath
POSIX cp(1) equivalent, but also copying tags: copy files and their tags into targetdir.
-f  Force: remove destination if it exists.
-i  Interactive: fail if the destination exists.
-n  No remove: fail if the destination exists.
-v  Verbose: show copied files.

*`FSTagsCommand.cmd_cptags(self, argv)`*:
Usage: {cmd} srcpath dstpath
Copy the direct tags from srcpath to dstpath.

*`FSTagsCommand.cmd_edit(self, argv)`*:
Usage: {cmd} [-ad] [path]
Edit the direct tagsets of path, default: '.'.
If path is a directory, provide the tags of its entries.
Otherwise edit just the tags for path.
-a    List all names in directory edit mode; normally
      names commencing with a dot are omitted.
-d    Treat directories like files: edit just its tags.

*`FSTagsCommand.cmd_export(self, argv, *, runstate: Optional[cs.resources.RunState] = <function uses_runstate.<locals>.<lambda> at 0x108790cc0>)`*:
Usage: {cmd} [-a] [--direct] path {{tag[=value]|-tag}}...
Export tags for files from paths matching all the constraints.
-a        Export all paths, not just those with tags.
--direct  Export the direct tags instead of the computed tags.
The output is in the same CSV format as that from "sqltags export",
with the following columns:
* unixtime: the file's st_mtime from os.stat.
* id: empty
* name: the file path
* tags: the file's direct or indirect tags

*`FSTagsCommand.cmd_find(self, argv, *, runstate: Optional[cs.resources.RunState] = <function uses_runstate.<locals>.<lambda> at 0x108790ea0>)`*:
Usage: {cmd} [--direct] [--for-rsync] [-o output_format] path {{tag[=value]|-tag}}...
List files from path matching all the constraints.
--direct    Use direct tags instead of all tags.
--for-rsync Instead of listing matching paths, emit a
            sequence of rsync(1) patterns suitable for use with
            --include-from in order to do a selective rsync of the
            matched paths.
-o output_format
            Use output_format as a Python format string to lay out
            the listing.
            Default: {FIND_OUTPUT_FORMAT_DEFAULT}

*`FSTagsCommand.cmd_import(self, argv)`*:
Usage: {cmd} {{-|srcpath}}...
Import CSV data in the format emitted by "export".
Each argument is a file path or "-", indicating standard input.

*`FSTagsCommand.cmd_infer(self, argv)`*:
Usage: {cmd} pathname
Print the base and inferred tags for pathname.

*`FSTagsCommand.cmd_json_import(self, argv)`*:
Usage: json_import --prefix=tag_prefix {{-|path}} {{-|tags.json}}
Apply JSON data to path.
A path named "-" indicates that paths should be read from
the standard input.
The JSON tag data come from the file "tags.json"; the name
"-" indicates that the JSON data should be read from the
standard input.

*`FSTagsCommand.cmd_ln(self, argv)`*:
Usage: {cmd} [-finv] srcpath dstpath, {cmd} [-finv] srcpaths... dstdirpath
POSIX ln(1) equivalent, but also copying the tags: link files and their tags into targetdir.
-f  Force: remove destination if it exists.
-i  Interactive: fail if the destination exists.
-n  No remove: fail if the destination exists.
-v  Verbose: show linked files.

*`FSTagsCommand.cmd_ls(self, argv, *, runstate: Optional[cs.resources.RunState] = <function uses_runstate.<locals>.<lambda> at 0x108791440>)`*:
Usage: {cmd} [-dlr] [--direct] [-o output_format] [paths...]
List files from paths and their tags.
-d          Treat directories like files, do not recurse.
--direct    List direct tags instead of all tags.
-l          Long format.
-o output_format
            Use output_format as a Python format string to lay out
            the listing.
            Default: {LS_OUTPUT_FORMAT_DEFAULT}
-r          Recurse into subdirectories.

*`FSTagsCommand.cmd_mv(self, argv)`*:
Usage: {cmd} [-finv] srcpath dstpath, {cmd} [-finv] srcpaths... dstdirpath
POSIX mv(1) equivalent, but also copying the tags: move files and their tags into targetdir.
-f  Force: remove destination if it exists.
-i  Interactive: fail if the destination exists.
-n  No remove: fail if the destination exists.
-v  Verbose: show moved files.

*`FSTagsCommand.cmd_ns(self, argv, runstate: Optional[cs.resources.RunState] = <function uses_runstate.<locals>.<lambda> at 0x108791940>)`*:
Usage: {cmd} [-d] [--direct] [paths...]
Report on the available primary namespace fields for formatting.
Note that because the namespace used for formatting has
inferred field names there are also unshown secondary field
names available in format strings.
-d          Treat directories like files, do not recurse.
--direct    List direct tags instead of all tags.

*`FSTagsCommand.cmd_ont(self, argv)`*:
Ontology operations.

Usage: {cmd} [subcommand [args...]]
  With no arguments, print the ontology.

*`FSTagsCommand.cmd_rename(self, argv)`*:
Usage: {cmd} -o basename_format paths...
Rename paths according to a format string.
-o basename_format
    Use basename_format as a Python format string to
    compute the new basename for each path.

*`FSTagsCommand.cmd_scrub(self, argv)`*:
Usage: {cmd} paths...
Remove all tags for missing paths.
If a path is a directory, scrub the immediate paths in the directory.

*`FSTagsCommand.cmd_tag(self, argv)`*:
Usage: {cmd} {{-|path}} {{tag[=value]|-tag}}...
Tag a path with multiple tags.
With the form "-tag", remove that tag from the direct tags.
A path named "-" indicates that paths should be read from the
standard input.

*`FSTagsCommand.cmd_tagfile(self, argv)`*:
Usage: {cmd} tagfile_path [subcommand ...]
Perform operations on a tag file.
Subcommands:
  tag tagset_name {{tag[=value]|-tag}}...
    Directly modify tag_name within the tag file tagfile_path.

*`FSTagsCommand.cmd_tagpaths(self, argv)`*:
Usage: {cmd} {{tag[=value]|-tag}} {{-|paths...}}
Tag multiple paths.
With the form "-tag", remove the tag from the immediate tags.
A single path named "-" indicates that paths should be read
from the standard input.

*`FSTagsCommand.cmd_test(self, argv)`*:
Usage: {cmd} [--direct] path {{tag[=value]|-tag}}...
Test whether the path matches all the constraints.
--direct    Use direct tags instead of all tags.

*`FSTagsCommand.cmd_xattr_export(self, argv)`*:
Usage: {cmd} {{-|paths...}}
Import tag information from extended attributes.

*`FSTagsCommand.cmd_xattr_import(self, argv)`*:
Usage: {cmd} {{-|paths...}}
Update extended attributes from tags.

*`FSTagsCommand.import_csv_file(self, f, *, convert_name=None)`*:
Import CSV data from the file `f`.

Parameters:
* `f`: the source CSV file
* `convert_name`: a callable to convert each input name
  into a file path; the default is to use the input name directly

*`FSTagsCommand.run_context(self)`*:
Push the `FSTags`.
- <a name="FSTagsConfig"></a>`Class `FSTagsConfig(cs.fs.FSPathBasedSingleton)``: A configuration for fstags.

*`FSTagsConfig.__init__(self, rcfilepath=None, physical=None)`*:
Initialise the config.

Parameters:
* `rcfilepath`: the path to the confguration file
  If `None`, default to `'~/.fstagsrc'` (from `RCFILE`).

*`FSTagsConfig.cascade_rules_from_config(config)`*:
Return a list of the `[cascade]` tag rules from the config.

*`FSTagsConfig.filename_rules_from_config(config)`*:
Return a list of the `[filename_autotag]` tag rules from the config.

*`FSTagsConfig.load_config(rcfilepath)`*:
Read an rc file, return a `ConfigParser` instance.

*`FSTagsConfig.tagsfile_basename`*:
The tags filename, default `'.fstags'`.
- <a name="FSTagsTagFile"></a>`Class `FSTagsTagFile(cs.tagset.TagFile, HasFSTagsMixin)``: A `FSTagsTagFile` indexing `TagSet`s for file paths
  which lives in the file path's directory.

*`FSTagsTagFile.TagSetClass(self, name: str) -> cs.fstags.TaggedPath`*:
Factory to create a `TaggedPath` from a `name`.

*`FSTagsTagFile.dirpath`*:
Return the path of the directory associated with this `FSTagsTagFile`.
- <a name="get_xattr_value"></a>`get_xattr_value(fspath, xattr_name)`: Read the extended attribute `xattr_name` of `fspath`.
  Return the extended attribute value as a string,
  or `None` if the attribute does not exist.

  Parameters:
  * `fspath`: the filesystem path to update
  * `xattr_name`: the extended attribute to obtain
    if this is a `str`, the attribute is the UTF-8 encoding of that name.
- <a name="HasFSTagsMixin"></a>`Class `HasFSTagsMixin``: Mixin providing an automatic `.fstags` property.

*`HasFSTagsMixin.fstags`*:
Return the `.fstags` property,
default a shared default `FSTags` instance.
- <a name="is_valid_basename"></a>`is_valid_basename(name: str)`: Test whether `name` is a valid basefile for something in a directory.
- <a name="main"></a>`main(argv=None)`: Command line mode.
- <a name="rsync_patterns"></a>`rsync_patterns(paths, top_path)`: Return a list of rsync include lines
  suitable for use with the `--include-from` option.
- <a name="TaggedPath"></a>`Class `TaggedPath(cs.tagset.TagSet, HasFSTagsMixin, cs.fs.HasFSPath)``: Class to manipulate the tags for a specific filesystem path.

*`TaggedPath.all_tags`*:
Cached cumulative tags for this path as a `TagSet`
by merging the tags from the root to the path.

Note that subsequent changes to some path component's `direct_tags`
will not affect this `TagSet`.

*`TaggedPath.as_tags(self, prefix=None, all_tags=False)`*:
Yield the tag data as `Tag`s.

This overrides `TagSet.as_tags`,
honouring an `optional `all_tags` parameter.

*`TaggedPath.auto_infer(self, attr)`*:
Infer a value from `attr` via the associated `FSTags.cascade_rules`.

This implementation tries the cascade rules from the configuration
and falls back to the superclass inference (the direct tag, if present).
Therefore a tagset with a rule for `.title` and also a
direct `.title` Tag would return the direct tag value for
`.title` and the rule value for `.auto.title`.

*`TaggedPath.basename`*:
The name of the final path component.

*`TaggedPath.cached_value(self, prefix: str, name: str, *, state_func: Optional[Callable[[str], Mapping[str, Any]]] = None) -> 'CachedValue'`*:
Return a `CachedValue` managing the `prefix.name` tag.

*`TaggedPath.export_xattrs(self)`*:
Update the extended attributes of the file.

*`TaggedPath.findup(self, check)`*:
Locate the first `TaggedPath` from `self` upwards (via `.parent`)
for which `check(TaggedPath)` is true.

*`TaggedPath.format_kwargs(self, *, direct=False)`*:
Format arguments suitable for `str.format_map`.

This returns an `ExtendedNamespace` from `TagSet.ns()`
for a computed `TagSet`.

In addition to the normal `TagSet.ns()` names
the following additional names are available:
* `fspath.basename`: basename of the `TaggedPath.fspath`
* `fspath.pathname`: the `TaggedPath.fspath`
* `fspath.encoded`: the JSON encoded fspath
* `tags`: the `TagSet` as a string

*`TaggedPath.format_tagset(self, *, direct=False)`*:
Compute a `TagSet` from this file's tags
with additional derived tags.

This can be converted into an `ExtendedNamespace`
suitable for use with `str.format_map`
via the `TagSet`'s `.format_kwargs()` method.

In addition to the normal `TagSet.ns()` names
the following additional names are available:
* `fspath.basename`: basename of the `TaggedPath.fspath`
* `fspath.ext`: the file extension of the basename
  of the `TaggedPath.fspath`
* `fspath.pathname`: the `TaggedPath.fspath`
* `fspath.encoded`: the JSON encoded fspath

*`TaggedPath.from_str(fspath, *, fstags: Optional[cs.fstags.FSTags] = <function <lambda> at 0x1087900e0>)`*:
Supports the `@promote` decorator.

*`TaggedPath.get_xattr_tagset(self, xattr_name=None)`*:
Return a new `TagSet`
from the extended attribute `xattr_name` of `self.fspath`.
The default `xattr_name` is `XATTR_B` (`None`).

*`TaggedPath.import_xattrs(self)`*:
Update the direct tags from the file's extended attributes.

*`TaggedPath.infer_from_basename(self, rules=None)`*:
Apply `rules` to the basename of this `TaggedPath`,
return a `TagSet` of inferred `Tag`s.

Tag values from earlier rules override values from later rules.

The default rules come from `self.fstags.config.filename_rules`,
which is sourced from `~/.fstagsrc`.

*`TaggedPath.infer_tags(self)`*:
Infer tags for this path.

In order of preference:
* from filesystem fstags
* from file basename matching
* from various `_type` suffixes
* from the cascade rules (see `FSTags.cascade_rules`)

*`TaggedPath.keypath`*:
The key path used to index this `TaggedPath` within its `FSTags`
from `FSTags.keypath(path)`.

*`TaggedPath.merged_tags(self)`*:
Compute the cumulative tags for this path as a new `TagSet`
by merging the tags from the root to the path.

*`TaggedPath.name`*:
The `.name` is `basename(self.fspath)`.

*`TaggedPath.parent`*:
A reference to the parent of this `TaggedPath`, or `None`.

*`TaggedPath.prune_inherited(self)`*:
Examine the tags of this path's parent.
Remove any tag on this file if they are present on the parent.
Return a `TagSet` containing the pruned `Tag`s.

*`TaggedPath.save(self, prune=True)`*:
Update the associated `FSTagsTagFile`.

*`TaggedPath.save_if_closed(self, **save_kw)`*:
Save the tag file is `self._fstags` is closed (no autosave).

*`TaggedPath.set(self, tag_name, value, **kw)`*:
Forbid the special tag name `'name'`, reserved for the filename.

*`TaggedPath.tagfile`*:
Return the `FSTagsTagFile` storing the state for this `TaggedPath`.

*`TaggedPath.update(self, other=None, **update_kw)`*:
Call `TagSet.update` with the `FSTags` open.
- <a name="TaggedPathSet"></a>`Class `TaggedPathSet``: A set of `TaggedPath` instances also indexed by their `Tag`s.

*`TaggedPathSet.__getitem__(self, key: Union[str, Tuple[str, Any], cs.tagset.Tag])`*:
Fetch matching `TaggedPath`s by `key`.
This looks up a tag name or a `(name,value)` pair or a `Tag`.

*`TaggedPathSet.add(self, path: cs.fstags.TaggedPath)`*:
Add `path` to the set.
This indexes its _current_ tag names and values.
To reindex a path, add it again.

*`TaggedPathSet.clear(self)`*:
Clear the set.

*`TaggedPathSet.discard(self, path: cs.fstags.TaggedPath)`*:
Discard `path` if known.
This removes `path` from the main set and the indices.

*`TaggedPathSet.update(self, paths: Iterable[Union[str, cs.fstags.TaggedPath]])`*:
Add `paths` to the set.
- <a name="update_xattr_value"></a>`update_xattr_value(fspath, xattr_name, new_xattr_value)`: Update the extended attributes of `fspath`
  with `new_xattr_value` for `xattr_name`.
  Return the previous value, or `None` if the attribute was missing.

  We avoid calling `os.setxattr` if the value will not change.

  Parameters:
  * `fspath`: the filesystem path to update
  * `xattr_name`: the extended attribute to update;
    if this is a `str`, the attribute is the UTF-8 encoding of that name.
  * `new_xattr_value`: the new extended attribute value, a `str`
    which should be the transcription of `TagSet`
    i.e. `str(tagset)`
- <a name="verbose"></a>`verbose(msg, *a)`: Emit message if in verbose mode.

# Release Log



*Release 20250528*:
* New TaggedPathSet implementing a set of TaggedPaths.
* FSTags.mv: link then remove to avoid tromping dstpath.

*Release 20241122*:
* FSTags.copy: use atomic_copy2 instead of shutil.copy2.
* FSTagsCommand: rename "-o ontology" to "-O ontology", modernise option specifications.

*Release 20241005*:
Assorted minor changes.

*Release 20240709*:
* New CachedValue class to manage a cached TaggedPath tag value.
* New TaggedPath.cached_value() method to return a CachedValue.

*Release 20240422*:
* Bugfix: .fstags files should no longer get Python repr() output for weirdly typed tag values.
* Some other minor internal updates.

*Release 20240412*:
Changes to accomodate dropping BaseCommandOptions.runstate.

*Release 20240316*:
* TaggedPath.infer_tags: add _dt, _date, _f conversions, skip conversions which raise TypeError or ValueError.
* rpaths: fix to yield relative paths.

*Release 20240211*:
* TaggedPath: subclass Promotable, add from_str(fspath) class method.
* FSTags: new mv(srcpath,dstpath) method to move/link/symlink a file bringing its tags.

*Release 20240201.1*:
Release with "fstags" script.

*Release 20240201*:
FSTags.attach_path: do not save the tagfile if the FSTags is open - the final close will do it.

*Release 20231129*:
FSTags.startup_shutdown: run self.sync() in a finally clause.

*Release 20230407*:
* FSTags: support open/close of self.update_mapping, update startup/shutdown to startup_shutdown.
* Move the (optional) ORM open/close from FSTags.startup_shutdown to TagFile.save, greatly shortens the ORM lock.

*Release 20230217*:
FSTagsCommand.cmd_rename: use -o for the format string as for other commands, -n is for "no action".

*Release 20230212*:
* FSTags.keypath(fspath) and TaggedPath.keypath with the singleton filesystem path for a TaggedPath.
* TaggedPath.parent property.
* TaggedPath.findup(check) method.
* FSTagsCommand: cmd_find,cmd_ls: abort if runstate.cancelled thus honouring SIGINT/^C.

*Release 20230211*:
FSTags.__init__: treat empty $FSTAGS_UPDATE_MAPPING as missing i.e. None.

*Release 20230210*:
New optional update_mapping for mirroring tags eg to an SQLTags; activated automatically by an $FSTAGS_UPDATE_MAPPING environment variable.

*Release 20221228*:
TaggedPath.save: new options prune=True parameter to drop empty top level dict/lists.

*Release 20220918*:
* FSTagsConfig: add empty .provided dict for config overrides.
* FSTagsConfig: set FSPATH_DEFAULT=RCFILE for use by FSPathBasedSingleton._singleton_key.
* FSTagsConfig: accept optional `physical` parameter to choose `realpath` over `abspath` and new `.physical` property.
* FSTags.__getitem__: use `abspath` or `realpath` depending on `self.config.physical`.
* FSTagsCommand: new -P option for "physical" mode, plumb though to the config and self.options.
* Provide a DEFAULT_FSTAGS instance and an @uses_fstags decorator.

*Release 20220606*:
FSTagsCommand.edit: mention the filename in the header comments in tagset edit mode.

*Release 20220430*:
Minor bugfixes.

*Release 20220311*:
* New TaggedPath.infer_tags() method to compute and return the inferred TagSet.
* New "fstags infer pathname" command.

*Release 20211212*:
* Rename edit_many to edit_tagsets for clarity.
* FSTags.edit_dirpath: include realpath(dirpath) at the top of the edit list.

*Release 20210906*:
* TaggedPath: new auto_infer method overriding the inherited TagSet.auto_infer which consults the cascade_rules from the .fstagsrc.
* fstags ls: new -l option to print a multiline tag listing.
* fstags cptags: copy the tags from one path to another.
* Assorted other changes.

*Release 20210404*:
* FSTags.edit_dirpath: new all_names parameter to include dot-names.
* FSTagsCommand.cmd_edit: new -a option to turn on the all_names parameter.

*Release 20210306*:
* FSTags: new tagfile_for(filepath) to obtain the TagFile for filepath.
* FSTagsCommand: new -o ontology option to supply an ontology file for the FSTags.
* FSTagsCommand.cmd_ont: drop -o/--ontology, superceded by global -o option.
* Move BaseTagFile from cs.fstags to TagFile in cs.tagset.
* FSTags.edit_dirpath: we now get (old_name,new_name,TaggedPath) back from edit_many, obviating the te_id_map.
* TaggedPath: .name property returning basename(self.filepath), .set and .discard methods rejecting use of the 'name' tag.
* FSTagsCommand: port to new cs.cmdutils API.
* Many small refactors and bugfixes.

*Release 20200717.1*:
Add the manual page MarkDown source files. Note: well out of date, need updating.

*Release 20200717*:
DISTINFO: require cs.obj>=20200716 for SingletonMixin API change.

*Release 20200716*:
* Update for changed cs.obj.SingletonMixin API.
* fstags: new "export" and "import" subcommands roughly paralleling those from "sqltags", providing CSV formatted export/import.
* fstags export: ew -a (all paths) option - the defau