# Upgrading the toolchain > Replaces the osy you are running with a newer release — downloaded, checked against the release's checksums, and swapped in place — on every platform, with one command. `osy whats-new` prints what changed first, and the toolchain tells you, once a day, when there is something to upgrade to. ## Summary {#summary} `osy upgrade` fetches the newest release for your platform, verifies it against the checksums the release publishes, and swaps it into the directory the running `osy` lives in. It works the same on macOS, Linux and Windows, which the install script does not. `osy whats-new` prints a release's notes in the terminal, and the toolchain prints one line a day when a newer version exists, ending with both commands. ## Signature {#signature} ```console osy upgrade # to the newest release osy upgrade 0.9.2 # to a particular version osy upgrade --check # only say whether a newer one exists osy whats-new # the newest release's notes osy whats-new 0.9.2 # a particular version's ``` ## Description {#description} **Where it comes from.** The download goes through the same door every install uses, so it is counted like any download, and the archive is checked against the `SHA256SUMS` the release carries before a byte of it is installed. A download that does not match is deleted and nothing changes. The version check and the notes come from the public release page, so neither is a statistic and neither reaches us. **How it swaps.** The files in the install directory are moved into a `.old/` folder beside them and the new files moved in — a rename, never a copy over a running program, which is what makes it safe to run from the very binary being replaced. The next run of `osy` removes the `.old/` folder. If anything fails during the swap the old files are moved back. **Your local platforms are replaced, not upgraded.** A compiled app and its embedded database belong to the compiler that made them — the platform model and the browser runtime both move between versions — so after the swap every local platform this installation started is stopped and removed, and the next `osy launch` or `osy check` starts a fresh one and recompiles your app. Data you seeded into a local platform is gone with it: these are development servers, never local production, and [Reclaiming the disk your local platforms use](https://osysharp.com/reference/local/reclaiming-local-disk/) removes the same directories on idleness. Your source, of course, is untouched. **The editor extension is a thin client of the toolchain** — the language server is `osy lsp`, hosted in the binary you just upgraded, so the editor is on the new compiler the moment it restarts the server. The extension itself is versioned with the toolchain; if an editor on your PATH has it at the previous version, the upgrade offers to update it, or names `osy vscode install` when it cannot ask ([Installing the editor extension](https://osysharp.com/reference/local/installing-the-editor-extension/)). **What it refuses.** An installation that a package manager owns — Homebrew's, winget's — because swapping files under a manager leaves it wrong about what is installed; the message names the manager's own upgrade command. **The daily line.** When a newer release exists the toolchain prints, before a command's own output and at most once a day, a line naming the version and the two commands. It is on whether or not usage statistics are; `"updateCheck": false` in `~/.osy/config.json` turns it off. See [Usage statistics (what is sent, and the two ids that let us count you once)](https://osysharp.com/reference/project/statistics/) for what the check sends (a request to the release page with the toolchain's user agent, and nothing else). ## Examples {#examples} ```console $ osy check a newer osy is available: 0.9.2 (you have 0.9.1) — osy upgrade what's new: osy whats-new · https://github.com/osysharp/cli/releases/tag/v0.9.2 … $ osy whats-new osy 0.9.2 (newer than yours) - … $ osy upgrade asking the release channel for the newest version… downloading osy 0.9.2 for darwin-arm64… checking it against the release's SHA256SUMS… unpacking… installing into /Users/you/.osy/bin… ✓ osy 0.9.2 installed (9 entries in /Users/you/.osy/bin). what changed: osy whats-new 2 local platform(s) from 0.9.1 removed (1 stopped first) — the next osy launch or osy check starts a fresh one and recompiles. code has the Osy# extension at 0.9.1; update it to 0.9.2 now? [Y/n] ``` ## See also {#see-also} [Installing the editor extension](https://osysharp.com/reference/local/installing-the-editor-extension/) — the extension that ships with each release. [Usage statistics (what is sent, and the two ids that let us count you once)](https://osysharp.com/reference/project/statistics/) — what the toolchain sends, and what the version check does not.