:toc: macro :toclevels: 5 :figure-caption!: = XDG [link=http://badge.fury.io/rb/xdg] image::https://badge.fury.io/rb/xdg.svg[Gem Version] [link=https://www.alchemists.io/projects/code_quality] image::https://img.shields.io/badge/code_style-alchemists-brightgreen.svg[Alchemists Style Guide] [link=https://circleci.com/gh/bkuhlmann/xdg] image::https://circleci.com/gh/bkuhlmann/xdg.svg?style=svg[Circle CI Status] Provides a Ruby implementation of the https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html[XDG Base Directory Specification] for managing common configurations without polluting your dotfiles. XDG is great for command line interfaces or any application that needs a common configuration, cache, data, or runtime. 💡 If you write a lot of Command Line Interfaces and would like additional/advanced syntactic sugar that includes what is found in this gem, make sure to check out the link:https://www.alchemists.io/projects/runcom[Runcom] gem too. toc::[] == Features * Provides a `XDG::Environment` 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` ** `$XDG_DATA_DIRS` == Requirements . https://www.ruby-lang.org[Ruby] == Setup To install, run: [source,bash] ---- gem install xdg ---- Add the following to your Gemfile: [source,ruby] ---- gem "xdg" ---- == Usage The following describes how to use this XDG implementation. === Overview To get up and running quickly, use `+XDG::Environment+` as follows: [source,ruby] ---- xdg = XDG::Environment.new xdg.cache_home # <= Answers computed `$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. ---- The _computed_ value, in this case, 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. The `XDG::Environment` wraps the following objects which can be used individually if you don’t want to load the entire environment: [source,ruby] ---- cache = XDG::Cache.new config = XDG::Config.new data = XDG::Data.new ---- The `cache`, `config`, and `data` objects share the same API which means you can ask each 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 `$XDG_*_HOME` prefixed at the start of the array). === Examples The following are examples of what you would see when playing around with the XDG objects within an IRB console (taken from my own environment): [source,ruby] ---- require "xdg" # Initialization environment = XDG::Environment.new cache = XDG::Cache.new config = XDG::Config.new data = XDG::Data.new # Inspection environment.inspect # => XDG_CACHE_HOME=/Users/bkuhlmann/.cache XDG_CONFIG_HOME=/Users/bkuhlmann/.config XDG_CONFIG_DIRS=/etc/xdg XDG_DATA_HOME=/Users/bkuhlmann/.local/share XDG_DATA_DIRS=/usr/local/share:/usr/share cache.inspect # => "XDG_CACHE_HOME=/Users/bkuhlmann/.cache" config.inspect # => "XDG_CONFIG_HOME=/Users/bkuhlmann/.config XDG_CONFIG_DIRS=/etc/xdg" data.inspect # => "XDG_DATA_HOME=/Users/bkuhlmann/.local/share XDG_DATA_DIRS=/usr/local/share:/usr/share" # Paths environment.cache_home # => # environment.config_home # => # environment.config_dirs # => [#] environment.data_home # => # environment.data_dirs # => [#, #] cache.home # => # cache.directories # => [] cache.all # => [#] config.home # => # config.directories # => [#] config.all # => [#, #] data.home # => # data.directories # => [#, #] data.all # => [#, #, #] ---- As you can see from above, each XDG object answers back a `Pathname` which means you have the full `Pathname` API at your fingertips to build upon the output of these objects as needed. === Variable Defaults The _XDG Base Directory Specification_ defines environment variables and associated default values when not defined or empty. The following defaults, per specification, are implemented by the `XDG` objects: * `$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` The `$XDG_RUNTIME_DIR` deserves special mention as it’s not, _currently_, implemented as part of this gem because it is more user/environment specific. Here is how the `$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: * `$XDG_*_HOME` * `$XDG_*_DIRS` Each is described in detail below. ==== `$XDG_*_DIRS` These variables are used to define a colon (`:`) delimited list of directories. Order is important as the first directory defined will take precedent over the following directory and so forth. For example, here is a situation where the `XDG_CONFIG_DIRS` key has a custom value: [source,bash] ---- XDG_CONFIG_DIRS="/example/one/.config:/example/two/.settings:/example/three/.configuration" ---- Yields the following, colon delimited, array: [source,ruby] ---- [ "/example/one/.config", "/example/two/.settings", "/example/three/.configuration" ] ---- In the above example, the `"/example/one/.config"` path takes _highest_ priority since it was defined first. ==== `$XDG_*_HOME` 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="/example/priority" XDG_CONFIG_DIRS="/example/one/.config:/example/two/.settings" ---- Yields the following, colon delimited, array: [source,ruby] ---- [ "/example/priority", "/example/one/.config", "/example/two/.settings" ] ---- Due to `XDG_CONFIG_HOME` taking precedence over the `XDG_CONFIG_DIRS`, the path with the _highest_ priority in this example is: `"/example/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/bkuhlmann/xdg.git cd xdg bin/setup ---- You can also use the IRB console for direct access to all objects: [source,bash] ---- bin/console ---- == Tests To test, run: [source,bash] ---- bundle exec rake ---- == Versioning Read link:https://semver.org[Semantic Versioning] for details. Briefly, it means: * Major (X.y.z) - Incremented for any backwards incompatible public API changes. * Minor (x.Y.z) - Incremented for new, backwards compatible, public API enhancements/fixes. * Patch (x.y.Z) - Incremented for small, backwards compatible, bug fixes. == Code of Conduct Please note that this project is released with a link:CODE_OF_CONDUCT.adoc[CODE OF CONDUCT]. By participating in this project you agree to abide by its terms. == Contributions Read link:CONTRIBUTING.adoc[CONTRIBUTING] for details. == License Read link:LICENSE.adoc[LICENSE] for details. == History Read link:CHANGES.adoc[CHANGES] for details. == Credits Engineered by link:https://www.alchemists.io/team/brooke_kuhlmann[Brooke Kuhlmann].