bun just runs justfile recipes through Bun's linked Rust task runner. It searches the current directory and its parents for justfile or .justfile.
test:
bun test
build: test
bun build ./src/index.ts --outdir dist
bun just --list
bun just test
bun just --dry-run build
Recipes preserve Just's default sh -cu interpreter. On Windows, install a POSIX shell and make sh available on PATH, or select another interpreter with set windows-shell.
Use bun just --bun-shell recipe to select Bun Shell explicitly. It runs with unset-variable checking and does not implement every POSIX shell feature. Explicit set shell, set windows-shell, command-line shell options and shebang recipes keep their configured interpreters. Recipe dependencies, arguments, variables, imports, modules, dotenv files, listing, formatting and exit codes follow the embedded just implementation.
Enable set positional-arguments or add [positional-arguments] to a recipe to receive its name as $0 and its arguments as $1, $2, and so on:
set positional-arguments
greet name:
@printf '%s: %s\n' "$0" "$1"
bun just greet 'Bun user' prints greet: Bun user. In shell(command, args...), $0 is the command string and the additional arguments start at $1.
Use bun --cwd path/to/project just build to select a project. Options after just belong to the recipe runner:
bun just --justfile tasks.just --working-directory . --list
bun just --fmt --check
bun just --dump --dump-format json
A package script named just takes precedence over the built-in command, following Bun's other project commands. A script containing bun just enters the built-in runner.
In Bun Shell recipes, {{just_command()}} returns a quoted invocation of the embedded runner, including the just subcommand. Use it for recursive recipes. just_executable() keeps its upstream contract and returns only the executable path.
The recursive command preserves --bun-shell when selected.
Children of the embedded runner inherit npm_lifecycle_event=just, so recursive calls stay in the built-in runner even when a recipe changes to a directory containing a package script named just.
again:
{{just_command()}} test
The recipe runner lives under src/just in Bun's root Cargo workspace and is compiled into Bun. Running recipes does not download a separate task runner. bun just --help lists the available options.