Add Install Latest Version Of Ruby With asdf as a Ruby TIL

ruby/install-latest-version-of-ruby-with-asdf.md

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+# Install Latest Version Of Ruby With asdf
+
+When I check the `asdf` Ruby plugin for known versions of Ruby:
+
+```bash
+$ asdf list-all ruby | fzf
+```
+
+I don't find the latest (`3.4`).
+
+I need to update the plugin. A newer version of the plugin will know about
+newer Ruby versions.
+
+```bash
+$ asdf plugin-update ruby
+```
+
+Now, if I run the `list-all` command again, I'll find the version I'm looking
+for — `3.4.1`.
+
+Now that `asdf` and I both know about the version to be installed, I can tell
+`asdf` to install it:
+
+```bash
+$ asdf install ruby 3.4.1
+```
+
+Now, if I check the current Ruby version, I'll see that it is still set to some
+other version.
+
+```bash
+$ ruby --version
+ruby 3.2.2 (2023-03-30 revision e51014f9c0) [x86_64-darwin22]
+```
+
+I need to tell `asdf` to start using this newly installed version instead,
+either globally or locally.
+
+```bash
+$ # globally
+$ asdf global ruby 3.4.1
+$ # or locally
+$ asdf local ruby 3.4.1
+```
+
+And now I'm all set:
+
+```bash
+$ asdf current ruby
+ruby            3.4.1           /Users/jbranchaud/.tool-versions
+
+$ ruby --version
+ruby 3.4.1 (2024-12-25 revision 48d4efcb85) +PRISM [x86_64-darwin22]
+```