CLI

The CLI comes with the package as preview. Run it from your app's root with your package manager: npx preview, bunx preview, pnpm exec preview or yarn preview. preview --help prints the same list.

preview <command> [options]

publish

Builds this app's JS bundle and uploads it as a preview. See Publishing.

Option	Default	What it does
`--id <id>`	the git branch	The preview's id. Publishing an id again replaces it
`--title <title>`	asked, prefilled from the id	The name QA sees. Without it a terminal asks; Enter keeps the readable id. No prompt without a terminal
`--platform <p>`	`all`	`android`, `ios` or `all`
`--base <branch>`	the repo's default branch	The branch the changelog counts commits from
`--changelog=<text>`	the commit subjects	Changelog text. Use `=` when it starts with a dash, as a `- item` list does
`--changelog-file <path>`		Read the changelog from a file
`--entry-file <path>`	Expo's own	Passed to `expo export:embed`
`--compatibility <c>`	the plugin option	`appVersion` or `fingerprint`. Overrides the app config, with a warning
`--environment <name>`		Build with this EAS environment's variables, like `eas update`. Needs eas-cli and a project linked to EAS; shell variables win. See Settings and env files

unpublish

preview unpublish <id>

Removes a preview from every build's list and deletes its manifests. Its files stay until prune. A copy already on a device stays there, shown as Unpublished.

prune

preview prune

Deletes every file in the bucket that no preview uses any more.

start

preview start [--title <title>] [--ports <from>-<to>] [-- <expo start args>]

Runs Metro on a free port and announces it to the app's Dev preview servers. See Dev preview servers.

Option	Default	What it does
`--title <title>`	asked, prefilled from the branch	The name the app's list shows. Asked like `publish`
`--ports <from>-<to>`	`8081-8099`	The ports to pick from
`-- <args>`		Everything after `--` goes to `expo start` untouched

Every command

Option	Default	What it does
`--project <dir>`	the current folder	The app's root
`-h`, `--help`		Print the help

Settings

publish, unpublish and prune need the bucket and the write key. They come from the environment (the shell, or CI secrets). For local use they can also go in the app's .env.local, or any env file Expo loads for a release build; the environment wins over them. Keep the write key out of a committed .env.

Variable	Needed	What it is
`PREVIEW_S3_URL`	Yes	`<endpoint>/<bucket>[/<folder>]`, for example `http://localhost:9000/previews-public`
`PREVIEW_S3_ACCESS_KEY_ID`	Yes	The write key
`PREVIEW_S3_SECRET_ACCESS_KEY`	Yes	Its secret
`PREVIEW_S3_REGION`	No	Default `us-east-1`

start needs none of them.

Exit codes

A command that fails prints preview: <message> and exits with 1.