Oils is our upgrade path from bash to a better language and runtime!
(The project was slightly renamed in March 2023, so there are still old references to "Oil". Feel free to send pull requests with corrections!)
Oils 2023 FAQ / Why Create a New Unix Shell?
It's written in Python, so the code is short and easy to change. But we automatically translate it to C++ with custom tools, to make it fast and small. The deployed executable doesn't depend on Python.
This README is at the root of the git repo.
#oil-dev channel of
oilshell.zulipchat.com, or file an issue on Github.
After following the instructions on the Contributing page, you'll have a Python program that you can quickly run and change! Try it interactively:
osh$ echo "hello $name"
Let us know if any of these things don't work! The continuous build tests them at every commit.
Again, note that the developer build is very different from the release tarball. The Contributing page describes this difference in detail.
The release tarballs are linked from the home page. (Developer builds don't work on OS X, so use the release tarballs on OS X.)
Oils is full of many ideas, which may be intimidating at first.
But the bar to contribution is very low. It's basically a medium size Python program with many tests, and many programmers know how to change such programs. It's great for prototyping.
grep xtrace spec/*.test.sh, where
xtrace is a shell feature.
The Wiki has many developer docs. Feel free to edit them. If you make a major change, let us know on Zulip!
There are also READMEs in some subdirectories, like
If you're confused, the best thing to do is to ask on Zulip and someone should produce a pointer and/or improve the docs.
Docs for end users are linked from each release page.
Try this to show a summary of what's in the repo and their line counts:
$ metrics/source-code.sh overview
(Other functions in this file may be useful as well.)
Oils is naturally structured as a set of mutually recursive parsers and evaluators. These interpreters are specified at a high-level: with regular languages, Zephyr ASDL, and a statically-typed subset of Python.
bin/ # Main entry points like bin/osh (source in bin/oils_for_unix.py)
frontend/ # Input and lexing common to OSH and YSH
osh/ # OSH parsers and evaluators (cmd, word, sh_expr)
ysh/ # YSH parser and evaluator
data_lang/ # Languages based on JSON
builtin/ # Builtin commands and functions
core/ # Other code shared between OSH and YSH
pyext/ # Python extension modules, e.g. libc.c
pylib/ # Borrowed from the Python standard library.
tools/ # User-facing tools, e.g. the osh2oil translator
Here are the tools that transform that high-level code to efficient code:
asdl/ # ASDL implementation, derived from CPython
pgen2/ # Parser Generator, borrowed from CPython
mycpp/ # Experimental translator from typed Python to C++.
# Depends on MyPy. See mycpp/README.md
pea/ # Perhaps a cleaner version of mycpp
opy/ # Python compiler in Python (mycpp/ will replace it)
We have native code to support both the dev build (running under CPython) and
oils-for-unix build (pure C++):
NINJA-config.sh # Generates build.ninja
build/ # High level build
NINJA_main.py # invoked by NINJA-config.sh
oil-defs/ # Files that define our slice of CPython.
py.sh # For development builds, running CPython
cpp/ # C++ code which complements the mycpp translation
mycpp/ # Runtime for the translator
prebuilt/ # Prebuilt files committed to git, instead of in _gen/
Python-2.7.13/ # For the slow Python build
# Temp dirs (see below)
Unit tests are named
foo_test.py and live next to
test/ # Test automation
gold/ # Gold Test cases
sh_spec.py # shell spec test framework
spec.sh # Types of test runner: spec, unit, gold, wild
spec/ # Spec test cases
bin/ # tools used in many spec tests
testdata/ # scripts for specific test cases
stateful/ # Tests that use pexpect
We use a lot of automation to improve the dev process. It's largely written in shell, of course!
benchmarks/ # Benchmarks should be run on multiple machines.
metrics/ # Metrics don't change between machines (e.g. code size)
client/ # Demonstration of OSH as a headless server.
deps/ # Dev dependencies and Docker images
devtools/ # For Oils developers (not end users)
release.sh # The (large) release process.
services/ # talk to cloud services
demo/ # Demonstrations of bash/shell features. Could be
# moved to tests/ if automated.
old/ # A junk drawer.
web/ # HTML/JS/CSS for tests and tools
soil/ # Multi-cloud continuous build (e.g. sourcehut, Github)
Directories that begin with
_ are not stored in
git. The dev tools
above create and use these dirs.
_bin/ # Native executables are put here
_build/ # Temporary build files
_cache/ # Dev dependency tarballs
_devbuild/ # Generated Python code, etc.
_gen/ # Generated C++ code that mirrors the repo
_release/ # Source release tarballs are put here
VERSION/ # Published at oilshell.org/release/$VERSION/
web/ # Static files, copy of $REPO_ROOT/web
_test/ # Unit tests, mycpp examples
_tmp/ # Output of other test suites; temp files
These tools are built from shell scripts in
oil_DEPS dir is
"parallel" to Oils because it works better with container bind mounds.
re2c/ # to build the lexer
cmark/ # for building docs
spec-bin/ # shells to run spec tests against
mypy/ # MyPy repo
mycpp-venv/ # MyPy binaries deps in a VirtualEnv
py3/ # for mycpp and pea/
cpython-full/ # for bootstrapping Oils-CPython
These files make the slow "Oils Python" build, which is very different than the developer build of Oils.
These files are for the C++
oils-for-unix tarball (in progress):
doc/ # A mix of docs
doctools/ # Tools that use lazylex/ to transform Markdown/HTML
lazylex/ # An HTML lexer which doctools/ builds upon.
README.md # This page, which is For Oils developers
LICENSE.txt # For end users
There are README files in many subdirectories, like mycpp/README.md.