asdf vs RVM

asdf is a free, open-source version manager for Linux and macOS. It gives project teams one command interface and a shared `.tool-versions` file for selecting exact versions of multiple tools and runtimes. Plugins support tools such as Node.js, Ruby, and Elixir, while the plugin API allows additional tools. When a command runs, asdf searches for configuration from the current directory upward toward the home directory, then uses shims to launch the selected executable. Existing `.ruby-version`, `.nvmrc`, and `.node-version` files can be supported per plugin. Listed shell support includes Bash, ZSH, Fish, and Elvish, with completions. A GitHub Action uses `.tool-versions` in CI/CD workflows. Installation options include Homebrew, Zypper, Pacman, precompiled binaries, Go, and source builds. asdf manages tool versions rather than system packages or upstream dependencies. If no version is set, execution errors unless the tool is configured as `system`.

RVM is a command-line tool for installing and managing Ruby versions and gem sets. It can create a self-contained environment for each project, with a selected Ruby version and the gems that project needs. Named gemsets organize gems across Ruby versions, and a shared cache stores one on-disk copy of each downloaded gem. RVM can run test suites, rake tasks, benchmarks, and gem commands against multiple Ruby versions at the same time, supporting consistent setups across development, CI, QA, staging, and production. Its commands cover installing, selecting, upgrading, reinstalling, uninstalling, and removing Ruby versions. Documented integrations include Bundler, Capistrano, Chef, Jenkins, Heroku, and Passenger. RVM supports most UNIX-like systems and Windows through Cygwin or Bash on Ubuntu on Windows. Basic installation needs Bash, curl, gpg2, and GNU tools; git is needed for head Ruby versions. It documents single-user, multi-user, and mixed-mode installs, and recommends single-user mode for an isolated home-directory setup. RVM is free and maintained by community volunteers.