---

name: justfile-authoring description: Create, edit, or review justfiles for the just command runner. Use when adding or modifying recipes, parameters, dependencies, settings, attributes, aliases, or shebang scripts; fixing invocation or working-directory behavior; or documenting tasks for just --list output.

Justfile Authoring

Follow existing conventions

• Locate the nearest justfile or .justfile to the working directory and edit in place.
• Preserve naming style, indentation, and grouping conventions.
• Keep diffs minimal; avoid renaming recipes unless requested.

Edit workflow

1. Read the existing justfile top to bottom; note set directives, variables, aliases, and groups.
2. Add or update recipes using the same structure and indentation.
3. Ensure dependencies and parameters are correct and consistent.
4. If a recipe should be hidden from listings, mark it private or prefix with _.

Syntax essentials

• Recipe:

  Copybuild target="app": clean
      cargo build --release --bin {{target}}
  

• Dependencies: run before the recipe body; parameterized deps are wrapped in parentheses.

  Copyrebuild: clean build
  build arch: (clean arch)
      cargo build --target {{arch}}
  

• Parameters: defaults supported; variadics use * (zero or more) or + (one or more).

  Copytest suite="all":
      cargo test --tests {{suite}}
  
  backup *files:
      tar czf backup.tar.gz {{files}}
  

• Exported parameters: prefix with $ to pass as environment variables.

  Copytest-with-env $TEST_MODE:
      echo "$TEST_MODE"
  

• Variables and interpolation:

  Copyapp := "myapp"
  build:
      echo "{{app}}"
  

• Default recipe: place first if you want it to run with just.

  Copydefault:
      @just --list
  

Settings

Use set to configure behavior globally.

Copyset dotenv-load := true
set shell := ["bash", "-eo", "pipefail", "-c"]
set working-directory := "ios"

Attributes and helpers

Common attributes:

• [group('name')] or [group: 'name'] to categorize recipes in listings.
• [working-directory('path')] to override the cwd for one recipe.
• [private] to hide a recipe or alias from just --list.
• [doc('description')] to control list output text.
• [confirm('prompt')] to request confirmation.
• [linux], [macos], [windows] for platform-specific recipes.
• [no-cd] to run in the invoking directory instead of the justfile directory.
• [positional-arguments] for positional-argument recipes.

Aliases:

Copyalias b := build

Shebang recipes

For multi-line scripts, start the body with a shebang.

Copyrelease:
    #!/usr/bin/env bash
    set -euo pipefail
    ./scripts/release.sh

Editing checklist

• Keep indentation consistent (spaces or tabs, not both, within a recipe).
• Use @ on a line (or @ before the recipe name) to suppress command echoing.
• Prefer group and doc attributes for clarity in just --list.
• Avoid unused variables, aliases, or recipes.
• For repo-specific paths, anchor to the existing working-directory conventions.