coreutils/DEVELOPMENT.md

Setting up your local development environment

For contributing rules and best practices please refer to CONTRIBUTING.md

Before you start

For this guide we assume that you already have GitHub account and have git and your favorite code editor or IDE installed and configured. Before you start working on coreutils, please follow these steps:

1. Fork the coreutils repository to your GitHub account. Tip: See this GitHub guide for more information on this step.
2. Clone that fork to your local development environment:

git clone https://github.com/YOUR-GITHUB-ACCOUNT/coreutils
cd coreutils

Tools

You will need the tools mentioned in this section to build and test your code changes locally. This section will explain how to install and configure these tools. We also have an extensive CI that uses these tools and will check your code before it can be merged. The next section Testing will explain how to run those checks locally to avoid waiting for the CI.

Rust toolchain

Install Rust

If you're using rustup to install and manage your Rust toolchains, clippy and rustfmt are usually already installed. If you are using one of the alternative methods, please make sure to install them manually. See following sub-sections for their usage: clippy rustfmt.

Tip You might also need to add 'llvm-tools' component if you are going to generate code coverage reports locally:

rustup component add llvm-tools-preview

GNU utils and prerequisites

If you are developing on Linux, most likely you already have all/most GNU utilities and prerequisites installed.

To make sure, please check GNU coreutils README-prereq.

You will need these to run uutils against the GNU test suite locally.

For MacOS and Windows platform specific setup please check MacOS GNU utils and Windows GNU utils sections respectfully.

pre-commit hooks

A configuration for pre-commit is provided in the repository. It allows automatically checking every git commit you make to ensure it compiles, and passes clippy and rustfmt without warnings.

To use the provided hook:

1. Install pre-commit
2. Run pre-commit install while in the repository directory

Your git commits will then automatically be checked. If a check fails, an error message will explain why, and your commit will be canceled. You can then make the suggested changes, and run git commit ... again.

NOTE: On MacOS the pre-commit hooks are currently broken. There are workarounds involving switching to unstable nightly Rust and components.

clippy

cargo clippy --all-targets --all-features

The msrv key in the clippy configuration file clippy.toml is used to disable lints pertaining to newer features by specifying the minimum supported Rust version (MSRV).

rustfmt

cargo fmt --all

cargo-deny

This project uses cargo-deny to detect duplicate dependencies, checks licenses, etc. To run it locally, first install it and then run with:

cargo deny --all-features check all

Markdown linter

We use markdownlint to lint the Markdown files in the repository.

Spell checker

We use cspell as spell checker for all files in the project. If you are using VS Code, you can install the code spell checker extension to enable spell checking within your editor. Otherwise, you can install cspell separately.

If you want to make the spell checker ignore a word, you can add

// spell-checker:ignore word_to_ignore

at the top of the file.

Testing

This section explains how to run our CI checks locally. Testing can be done using either Cargo or make.

Testing with Cargo

Just like with building, we follow the standard procedure for testing using Cargo:

cargo test

By default, cargo test only runs the common programs. To run also platform specific tests, run:

cargo test --features unix

If you would prefer to test a select few utilities:

cargo test --features "chmod mv tail" --no-default-features

If you also want to test the core utilities:

cargo test  -p uucore -p coreutils
# or
cargo test --all-features -p uucore

Running the complete test suite might take a while. We use nextest in the CI and you might want to try it out locally. It can speed up the execution time of the whole test run significantly if the cpu has multiple cores.

cargo nextest run --features unix --no-fail-fast

To debug:

gdb --args target/debug/coreutils ls
(gdb) b ls.rs:79
(gdb) run

Testing with GNU Make

To simply test all available utilities:

make test

To test all but a few of the available utilities:

make SKIP_UTILS='UTILITY_1 UTILITY_2' test

To test only a few of the available utilities:

make UTILS='UTILITY_1 UTILITY_2' test

To include tests for unimplemented behavior:

make UTILS='UTILITY_1 UTILITY_2' SPEC=y test

To run tests with nextest just use the nextest target. Note you'll need to install nextest first. The nextest target accepts the same arguments like the default test target, so it's possible to pass arguments to nextest run via CARGOFLAGS:

make CARGOFLAGS='--no-fail-fast' UTILS='UTILITY_1 UTILITY_2' nextest

Run Busybox Tests

This testing functionality is only available on *nix operating systems and requires make.

To run busybox tests for all utilities for which busybox has tests

make busytest

To run busybox tests for a few of the available utilities

make UTILS='UTILITY_1 UTILITY_2' busytest

To pass an argument like "-v" to the busybox test runtime

make UTILS='UTILITY_1 UTILITY_2' RUNTEST_ARGS='-v' busytest

Comparing with GNU

To run uutils against the GNU test suite locally, run the following commands:

bash util/build-gnu.sh
# Build uutils without release optimizations
UU_MAKE_PROFILE=debug bash util/build-gnu.sh
bash util/run-gnu-test.sh
# To run a single test:
bash util/run-gnu-test.sh tests/touch/not-owner.sh # for example
# To run several tests:
bash util/run-gnu-test.sh tests/touch/not-owner.sh tests/rm/no-give-up.sh # for example
# If this is a perl (.pl) test, to run in debug:
DEBUG=1 bash util/run-gnu-test.sh tests/misc/sm3sum.pl

Tip: First time you run bash util/build-gnu.sh command, it will provide instructions on how to checkout GNU coreutils repository at the correct release tag. Please follow those instructions and when done, run bash util/build-gnu.sh command again.

Note that GNU test suite relies on individual utilities (not the multicall binary).

Code coverage report

Code coverage report can be generated using grcov.

Using Nightly Rust

To generate gcov-based coverage report

export CARGO_INCREMENTAL=0
export RUSTFLAGS="-Zprofile -Ccodegen-units=1 -Copt-level=0 -Clink-dead-code -Coverflow-checks=off -Zpanic_abort_tests -Cpanic=abort"
export RUSTDOCFLAGS="-Cpanic=abort"
cargo build <options...> # e.g., --features feat_os_unix
cargo test <options...> # e.g., --features feat_os_unix test_pathchk
grcov . -s . --binary-path ./target/debug/ -t html --branch --ignore-not-existing --ignore build.rs --excl-br-line "^\s*((debug_)?assert(_eq|_ne)?\#\[derive\()" -o ./target/debug/coverage/
# open target/debug/coverage/index.html in browser

if changes are not reflected in the report then run cargo clean and run the above commands.

Using Stable Rust

If you are using stable version of Rust that doesn't enable code coverage instrumentation by default then add -Z-Zinstrument-coverage flag to RUSTFLAGS env variable specified above.

Tips for setting up on Mac

C Compiler and linker

On MacOS you'll need to install C compiler & linker:

xcode-select --install

MacOS GNU utils

On MacOS you will need to install Homebrew and use it to install the following Homebrew formulas:

brew install \
  coreutils \
  autoconf \
  gettext \
  wget \
  texinfo \
  xz \
  automake \
  gnu-sed \
  m4 \
  bison \
  pre-commit \
  findutils

After installing these Homebrew formulas, please make sure to add the following lines to your zsh or bash rc file, i.e. ~/.profile or ~/.zshrc or ~/.bashrc ... (assuming Homebrew is installed at default location /opt/homebrew):

eval "$(/opt/homebrew/bin/brew shellenv)"
export PATH="/opt/homebrew/opt/coreutils/libexec/gnubin:$PATH"
export PATH="/opt/homebrew/opt/bison/bin:$PATH"
export PATH="/opt/homebrew/opt/findutils/libexec/gnubin:$PATH"

Last step is to link Homebrew coreutils version of timeout to /usr/local/bin (as admin user):

sudo ln -s /opt/homebrew/bin/timeout /usr/local/bin/timeout

Do not forget to either source updated rc file or restart you terminal session to update environment variables.

Tips for setting up on Windows

MSVC build tools

On Windows you'll need the MSVC build tools for Visual Studio 2013 or later.

If you are using rustup-init.exe to install Rust toolchain, it will guide you through the process of downloading and installing these prerequisites.

Otherwise please follow this guide.

Windows GNU utils

If you have used Git for Windows to install git on you Windows system you might already have some GNU core utilities installed as part of "GNU Bash" included in Git for Windows package, but it is not a complete package. This article provides instruction on how to add more to it.

Alternatively you can install Cygwin and/or use WSL2 to get access to all GNU core utilities on Windows.