Support XDG layout on Linux

[peterhoeg]

Currently, we get a directory named $HOME/.MQTTnetApp i which the various configuration files are written.

It would be great to follow the XDG Base Directory Specification https://specifications.freedesktop.org/basedir-spec/basedir-spec-latest.html so as to not pollute $HOME.

Secondly, the casing is rather annoying on a case-sensitive file system where application directories are typically kept lower case. bash as an example will not auto-complete that out-of-the-box unless you get the casing right when typing the first letters.

[chkr1011]

Thanks for your feedback. Could you please share full samples for me because I am not that much familiar with Linux. Changing the directories will also require a migration component which will move the existing files around (or at least tries to read from the previous location etc.)

[peterhoeg]

It basically boils down to separating the various types of data which currently goes into `$HOME/.MQTTnetApp`. - `$XDG_CONFIG_HOME/mqttnetapp', this would be the actual configuration with the files Connections.json, Publish.json and Subscriptions.json - `XDG_CACHE_HOME/mqttnetapp', this is for any state data that can basically be deleted any time without anything negative consequences - `XDG_DATA_HOME/mqttnetapp', data that you want to keep but is not strictly configuration Other applications that have made this transition (and there’s quite a lot) have been following different approaches that basically boil down to: 1. if neither `$XDG_CONFIG_HOME/mqttnetapp' nor `$HOME/.MQTTnetApp' exist (because it’s the first run), use the new location 2. if both exist, error out 3. if the legacy location exists, either: 1. move the files into the new locations, or 2. continue using the legacy location Apologies for the borked formatting.

[chkr1011]

@peterhoeg Do you plan to update the package in NixOS?

[peterhoeg]

Thanks for the fix!

NixOS/nixpkgs#294665