:toc: macro :toclevels: 5 :figure-caption!: :dotfiles_link: link:https://alchemists.io/projects/dotfiles[Dotfiles] :runcom_link: link:https://alchemists.io/projects/runcom[Runcom] :sod_link: link:https://alchemists.io/projects/sod[Sod] = XDG Provides a Ruby implementation of the link:https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html[XDG Base Directory Specification] for managing common configurations without polluting your {dotfiles_link}. XDG is great for command line interfaces or any application that needs a common configuration, cache, data, state, or runtime. 💡 If you write a lot of Command Line Interfaces (CLIs) and would like additional behavior built atop this gem, then check out the {runcom_link} gem or the more advanced {sod_link} gem. toc::[] == Features * Provides a `XDG` object that adheres to the _XDG Base Directory Specification_ with access to the following environment settings: ** `$XDG_CACHE_HOME` ** `$XDG_CONFIG_HOME` ** `$XDG_CONFIG_DIRS` ** `$XDG_DATA_HOME` ** `$XDG_DATA_DIRS` ** `$XDG_STATE_HOME` == Requirements . https://www.ruby-lang.org[Ruby] == Setup To install _with_ security, run: [source,bash] ---- # 💡 Skip this line if you already have the public certificate installed. gem cert --add <(curl --compressed --location https://alchemists.io/gems.pem) gem install xdg --trust-policy HighSecurity ---- To install _without_ security, run: [source,bash] ---- gem install xdg ---- You can also add the gem directly to your project: [source,bash] ---- bundle add xdg ---- Once the gem is installed, you only need to require it: [source,ruby] ---- require "xdg" ---- == Usage The following describes how to use this implementation. === Objects To get up and running quickly, use `XDG.new` as follows: [source,ruby] ---- xdg = XDG.new xdg.cache_home # Answers computed `$XDG_CACHE_HOME` value. xdg.config_home # Answers computed `$XDG_CONFIG_HOME` value. xdg.config_dirs # Answers computed `$XDG_CONFIG_DIRS` value. xdg.data_home # Answers computed `$XDG_DATA_HOME` value. xdg.data_dirs # Answers computed `$XDG_DATA_DIRS` value. xdg.state_home # Answers computed `$XDG_STATE_HOME` value. ---- Behinds the scenes, use of `XDG.new` wraps `XDG::Environment.new` which provides a unified Object API to the following objects: [source,ruby] ---- cache = XDG::Cache.new config = XDG::Config.new data = XDG::Data.new state = XDG::State.new ---- Generally, use of `XDG.new` is all you need but knowing you can create a specialized instance of any aspect of the XDG specification can be handy for specific use cases. Additionally, the `cache`, `config`, `data`, and `state` objects share the same API which means you can send the following messages: * `#home`: Answers the home directory as computed via the `$XDG_*_HOME` key. * `#directories`: Answers an array directories as computed via the `$XDG_*_DIRS` key. * `#all`: Answers an array of _all_ directories as computed from the combined `$XDG_*_HOME` and `$XDG_*_DIRS` values (with `$XDG_*_HOME` prefixed at the start of the array). * `#to_s`: Answers an _explicit_ string cast for the current environment. * `#to_str`: Answers an _implicit_ string cast for the current environment. * `#inspect`: Answers object inspection complete with object type, object ID, and all environment variables. The _computed_ value of each method is either the user-defined value of the key or the default value, per specification, when the key is not defined or empty. For more on this, scroll down to the _Variable Defaults_ section to learn more. === Examples The following are examples of what you will see when exploring the XDG objects within an IRB console: [source,ruby] ---- require "xdg" # Initialization xdg = XDG.new cache = XDG::Cache.new config = XDG::Config.new data = XDG::Data.new state = XDG::State.new # Paths xdg.cache_home # "#" xdg.config_home # "#" xdg.config_dirs # ["#"] xdg.data_home # "#" xdg.data_dirs # ["#", "#"] xdg.state_home # "#" cache.home # "#" cache.directories # [] cache.all # ["#"] config.home # "#" config.directories # ["#"] config.all # ["#", "#"] data.home # "#" data.directories # ["#", "#"] data.all # ["#", "#", "#"] state.home # "#" state.directories # [] state.all # ["#"] # Casts (explicit and implicit) xdg.to_s # "XDG_CACHE_HOME=/Users/demo/.cache XDG_CONFIG_HOME=/Users/demo/.config XDG_CONFIG_DIRS=/etc/xdg XDG_DATA_HOME=/Users/demo/.local/share XDG_DATA_DIRS=/usr/local/share:/usr/share XDG_STATE_HOME=/Users/demo/.local/state" cache.to_s # "XDG_CACHE_HOME=/Users/demo/.cache" config.to_s # "XDG_CONFIG_HOME=/Users/demo/.config XDG_CONFIG_DIRS=/etc/xdg" data.to_s # "XDG_DATA_HOME=/Users/demo/.local/share XDG_DATA_DIRS=/usr/local/share:/usr/share" state.to_s # "XDG_STATE_HOME=/Users/demo/.local/state" xdg.to_str # "XDG_CACHE_HOME=/Users/demo/.cache XDG_CONFIG_HOME=/Users/demo/.config XDG_CONFIG_DIRS=/etc/xdg XDG_DATA_HOME=/Users/demo/.local/share XDG_DATA_DIRS=/usr/local/share:/usr/share XDG_STATE_HOME=/Users/demo/.local/state" cache.to_str # "XDG_CACHE_HOME=/Users/demo/.cache" config.to_str # "XDG_CONFIG_HOME=/Users/demo/.config XDG_CONFIG_DIRS=/etc/xdg" data.to_str # "XDG_DATA_HOME=/Users/demo/.local/share XDG_DATA_DIRS=/usr/local/share:/usr/share" state.to_str # "XDG_STATE_HOME=/Users/demo/.local/state" # Inspection xdg.inspect # "#" cache.inspect # "#" config.inspect # "#" data.inspect # "#" state.inspect # "#" ---- === Variable Defaults The _XDG Base Directory Specification_ defines environment variables and associated default values when not defined or empty. The following defaults, per specification, are implemented by the `XDG` objects: * `$XDG_CACHE_HOME="$HOME/.cache"` * `$XDG_CONFIG_HOME="$HOME/.config"` * `$XDG_CONFIG_DIRS="/etc/xdg"` * `$XDG_DATA_HOME="$HOME/.local/share"` * `$XDG_DATA_DIRS="/usr/local/share/:/usr/share/"` * `$XDG_RUNTIME_DIR` * `$XDG_STATE_HOME="$HOME/.local/state"` The `$XDG_RUNTIME_DIR` environment variable deserves special mention because it’s not, _currently_, implemented as part of this gem because it is more user/environment specific. Here is how the `$XDG_RUNTIME_DIR` is meant to be used should you choose to use it: * _Must_ reference user-specific non-essential runtime files and other file objects (such as sockets, named pipes, etc.) * _Must_ be owned by the user with _only_ the user having read and write access to it. * _Must_ have a Unix access mode of `0700`. * _Must_ be bound to the user when logging in. * _Must_ be removed when the user logs out. * _Must_ be pointed to the same directory when the user logs in more than once. * _Must_ exist from first login to last logout on the system and not removed in between. * _Must_ not allow files in the directory to survive reboot or a full logout/login cycle. * _Must_ keep the directory on the local file system and not shared with any other file systems. * _Must_ keep the directory fully-featured by the standards of the operating system. Specifically, on Unix-like operating systems AF_UNIX sockets, symbolic links, hard links, proper permissions, file locking, sparse files, memory mapping, file change notifications, a reliable hard link count must be supported, and no restrictions on the file name character set should be imposed. Files in this directory _may_ be subjected to periodic clean-up. To ensure files are not removed, they should have their access time timestamp modified at least once every 6 hours of monotonic time or the '`sticky`' bit should be set on the file. * When not set, applications should fall back to a replacement directory with similar capabilities and print a warning message. Applications should use this directory for communication and synchronization purposes and should not place larger files in it, since it might reside in runtime memory and cannot necessarily be swapped out to disk. === Variable Behavior The behavior of most XDG environment variables can be lumped into two categories: * `$XDG_*_DIRS` * `$XDG_*_HOME` Each is described in detail below. ==== Directories These variables are used to define a colon (`:`) delimited list of directories. Order is important as the first directory defined will take precedent over the following directory and so forth. For example, here is a situation where the `XDG_CONFIG_DIRS` key has a custom value: [source,bash] ---- XDG_CONFIG_DIRS="/demo/one/.config:/demo/two/.settings:/demo/three/.configuration" ---- The above then yields the following, colon delimited, array: [source,ruby] ---- [ "/demo/one/.config", "/demo/two/.settings", "/demo/three/.configuration" ] ---- In the above example, the `"/demo/one/.config"` path takes _highest_ priority since it was defined first. ==== Homes These variables take precedence over the corresponding `$XDG_*_DIRS` environment variables. Using a modified version of the `$XDG_*_DIRS` example, shown above, we could have the following setup: [source,bash] ---- XDG_CONFIG_HOME="/demo/priority" XDG_CONFIG_DIRS="/demo/one/.config:/demo/two/.settings" ---- The above then yields the following, colon delimited, array: [source,ruby] ---- [ "/demo/priority", "/demo/one/.config", "/demo/two/.settings" ] ---- Due to `XDG_CONFIG_HOME` taking precedence over the `XDG_CONFIG_DIRS`, the path with the _highest_ priority is: `"/demo/priority"`. === Variable Priority Path precedence is determined in the following order (with the first taking highest priority): . `$XDG_*_HOME` - Will be used if defined. Otherwise, falls back to specification default. . `$XDG_*_DIRS` - Iterates through directories in order defined (with first taking highest priority). Otherwise, falls back to specification default. == Development To contribute, run: [source,bash] ---- git clone https://github.com/demo/xdg cd xdg bin/setup ---- You can also use the IRB console for direct access to all objects: [source,bash] ---- bin/console ---- Lastly, there is a `bin/demo` script which displays default functionality for quick visual reference. This is the same script used to generate the usage examples shown at the top of this document. [source,bash] ---- bin/demo ---- == Tests To test, run: [source,bash] ---- bin/rake ---- == link:https://alchemists.io/policies/license[License] == link:https://alchemists.io/policies/security[Security] == link:https://alchemists.io/policies/code_of_conduct[Code of Conduct] == link:https://alchemists.io/policies/contributions[Contributions] == link:https://alchemists.io/projects/xdg/versions[Versions] == link:https://alchemists.io/community[Community] == Credits * Built with link:https://alchemists.io/projects/gemsmith[Gemsmith]. * Engineered by link:https://alchemists.io/team/brooke_kuhlmann[Brooke Kuhlmann].