elan vs RVM

elan manages installations of the Lean theorem prover on Linux, macOS and Windows. Its `lean` and `lake` binaries use a project’s `lean-toolchain` file to select the specified Lean version and download it when needed. The separate `elan` command provides manual control to install, select, run or uninstall Lean versions. The project supports version pinning, lockfiles, automatic switching, shell integration and CI/CD use. Installation options include shell instructions for Linux and macOS, a PowerShell method for Windows, and release downloads for supported platforms. The README recommends the Nixpkgs version on NixOS because toolchains downloaded by elan require patching there. Lake needs git to download dependencies. The project describes itself as a fork of rustup adapted for Lean infrastructure. elan is free at free, and the repository lists Apache-2.0 and MIT licenses. The releases page identifies v4.2.4 as the latest release.

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.