cs.fstags 20200130

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

Latest release 20200130: New FSTagsConfig class which parses the .fstagsrc as a .ini file; related adjustments. New HasFSTagsMixin presenting a settable .fstags property with a shared default. New xattr_import and xattr_export subcommands, remove implicit xattr access/update from other operations. New TagSet.len returning the number of tags. Add "-" support for stdin to "tag" and "tagpaths" subcommands.

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

Why fstags? By storing the tags in a separate file we:

• can store tags without modifying a file
• do no need to know the file's format, whether that supports metadata or not
• 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 with tags consisting of the directory entry name and the associated tags.

The 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 obtain the tags:

series.title="Series Full Name"
season=2
sf
episode=3
episode.title="Full Episode Title"

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"

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.

Class FSTags(cs.resources.MultiOpenMixin)

A class to examine filesystem tags.

Class FSTagsCommand(cs.cmdutils.BaseCommand)

fstags main command line class.

Command line usage:

Usage:
    FSTagsCommand autotag paths...
        Tag paths based on rules from the rc file.
    FSTagsCommand find [--for-rsync] 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: {filepath}
    FSTagsCommand ls [--direct] [-o output_format] [paths...]
        List files from paths and their tags.
        --direct    List direct tags instead of all tags.
        -o output_format
                    Use output_format as a Python format string to lay out
                    the listing.
                    Default: {filepath_encoded} {tags}
    FSTagsCommand mv paths... targetdir
        Move files and their tags into targetdir.
    FSTagsCommand tag {-|path} {tag[=value]|-tag}...
        Associate tags with a path.
        With the form "-tag", remove the tag from the immediate tags.
        A path named "-" indicates that paths should be read from the
        standard input.
    FSTagsCommand tagpaths {tag[=value]|-tag} {-|paths...}
        Associate a tag with 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 xattr_import {-|paths...}
        Import tag information from extended attributes.
    FSTagsCommand xattr_export {-|paths...}
        Update extended attributes from tags.

Class FSTagsConfig

A configuration for fstags.

Method FSTagsConfig.__init__(self, rcfilepath=None)

Initialise the config.

Parameters:

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

Function get_xattr_value(filepath, xattr_name)

Read the extended attribute xattr_name of filepath.

Return the extended attribute value as a string, or None if the attribute does not exist.

Parameters:

• filepath: 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.

Class HasFSTagsMixin

Mixin providing a .fstags property.

Function infer_tags(name, rules)

Infer Tags from name via rules. Return a TagSet.

rules is an iterable of objects with a .infer_tags(name) method which returns an iterable of Tags.

Function main(argv=None)

Command line mode.

Class RegexpTagRule

A regular expression based Tag rule.

Function rfilepaths(path, name_selector=None)

Generator yielding pathnames of files found under path.

Function rpaths(path, yield_dirs=False, name_selector=None)

Generator yielding pathnames found under path.

Function rsync_patterns(paths, top_path)

Return a list of rsync include lines suitable for use with the --include-from option.

Class Tag

A Tag has a .name (str) and a .value.

The name must be a dotted identifier.

A "bare" Tag has a value of None.

Class TagChoice(TagChoice,builtins.tuple)

A "tag choice", an apply/reject flag and a Tag, used to apply changes to a TagSet or as a criterion for a tag search.

Attributes:

• spec: the source text from which this choice was parsed, possibly None
• choice: the apply/reject flag
• tag: the Tag representing the criterion

Class TagFile(HasFSTagsMixin)

A reference to a specific file containing tags.

This manages a mapping of name => TagSet, itself a mapping of tag name => tag value.

Class TagFileEntry(builtins.tuple)

TagFileEntry(tagfile, name)

Class TaggedPath(HasFSTagsMixin)

Class to manipulate the tags for a specific path.

Class TagSet(HasFSTagsMixin)

A setlike class associating a set of tag names with values. A TagFile maintains one of these for each name.

Method TagSet.__init__(self, *, fstags=None, defaults=None)

Initialise the TagSet.

Parameters:

• defaults: a mapping of name->TagSet to provide default values.

Function update_xattr_value(filepath, xattr_name, new_xattr_value)

Update the extended attributes of filepath 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:

• filepath: 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)

Release Log

Release 20200130: New FSTagsConfig class which parses the .fstagsrc as a .ini file; related adjustments. New HasFSTagsMixin presenting a settable .fstags property with a shared default. New xattr_import and xattr_export subcommands, remove implicit xattr access/update from other operations. New TagSet.len returning the number of tags. Add "-" support for stdin to "tag" and "tagpaths" subcommands.

Release 20200113.2: FSTagsCommand docstring tweak.

Release 20200113.1: Small docstring updates.

Release 20200113: Mirror tags to user.cs.fstags xattr to honour Linux namespace requirements. Add "filesize" to available tag string format (-o option). Small bugfixes.

Release 20191230: Command line: new "find" command to search a file tree based on tags. Command line: new "mv" command to move a file and its tags. Command line: Python string formats for "find" and "ls" output. TaggedPath.autotag: new optional no_save parameter, default False, to suppress update of the associated .fstags file. Inital and untested "mirror tags to xattrs" support.

Release 20191201: New "edit" subcommand to rename files and edit tags.

Release 20191130.1: Initial release: fstags, filesystem based tagging utility.