bunx

Run packages from npm

bunx is an alias for bun x. The bunx CLI will be auto-installed when you install bun.

Use bunx to auto-install and run packages from npm. It’s Bun’s equivalent of npx or yarn dlx.

terminal

bunx cowsay "Hello world!"

⚡️ Speed — With Bun’s fast startup times, bunx is roughly 100x faster than npx for locally installed packages.

Packages can declare executables in the "bin" field of their package.json. These are known as package executables or package binaries.

package.json

{
  // ... other fields
  "name": "my-cli",
  "bin": {
    "my-cli": "dist/index.js"
  }
}

These executables are commonly plain JavaScript files marked with a shebang line to indicate which program should be used to execute them. The following file indicates that it should be executed with node.

dist/index.js

#!/usr/bin/env node

console.log("Hello world!");

These executables can be run with bunx,

terminal

bunx my-cli

As with npx, bunx will check for a locally installed package first, then fall back to auto-installing the package from npm. Installed packages will be stored in Bun’s global cache for future use.

Arguments and flags

To pass additional command-line flags and arguments through to the executable, place them after the executable name.

terminal

bunx my-cli --foo bar

---

Shebangs

By default, Bun respects shebangs. If an executable is marked with #!/usr/bin/env node, Bun will spin up a node process to execute the file. However, in some cases it may be desirable to run executables using Bun’s runtime, even if the executable indicates otherwise. To do so, include the --bun flag.

terminal

bunx --bun my-cli

The --bun flag must occur before the executable name. Flags that appear after the name are passed through to the executable.

terminal

bunx --bun my-cli # good
bunx my-cli --bun # bad

Package flag

--package <pkg> or -p <pkg> - Run binary from specific package. Useful when binary name differs from package name:

terminal

bunx -p renovate renovate-config-validator
bunx --package @angular/cli ng

To force bun to always be used with a script, use a shebang.

dist/index.js

#!/usr/bin/env bun

---

Usage

bunx [flags] <package>[@version] [flags and arguments for the package]

Execute an npm package executable (CLI), automatically installing into a global shared cache if not installed in node_modules.

Flags

--bun · boolean

Force the command to run with Bun instead of Node.js, even if the executable contains a Node shebang (#!/usr/bin/env node)

-p, --package · string

Specify package to install when binary name differs from package name

--no-install · boolean

Skip installation if package is not already installed

--verbose · boolean

Enable verbose output during installation

--silent · boolean

Suppress output during installation

Examples

terminal

# Run Prisma migrations
bunx prisma migrate

# Format a file with Prettier
bunx prettier foo.js

# Run a specific version of a package
bunx uglify-js@3.14.0 app.js

# Use --package when binary name differs from package name
bunx -p @angular/cli ng new my-app

# Force running with Bun instead of Node.js, even if the executable contains a Node shebang
bunx --bun vite dev foo.js