cosmopolitan

![Cosmopolitan Honeybadger](usr/share/img/honeybadger.png)

[![build](https://github.com/jart/cosmopolitan/actions/workflows/build.yml/badge.svg)](https://github.com/jart/cosmopolitan/actions/workflows/build.yml)
# Cosmopolitan

[Cosmopolitan Libc](https://justine.lol/cosmopolitan/index.html) makes C/C++
a build-once run-anywhere language, like Java, except it doesn't need an
interpreter or virtual machine. Instead, it reconfigures stock GCC and
Clang to output a POSIX-approved polyglot format that runs natively on
Linux + Mac + Windows + FreeBSD + OpenBSD 7.3 + NetBSD + BIOS with the
best possible performance and the tiniest footprint imaginable.

## Background

For an introduction to this project, please read the [actually portable
executable](https://justine.lol/ape.html) blog post and [cosmopolitan
libc](https://justine.lol/cosmopolitan/index.html) website. We also have
[API
documentation](https://justine.lol/cosmopolitan/documentation.html).

## Getting Started

You can start by obtaining a release of our `cosmocc` compiler from
<https://cosmo.zip/pub/cosmocc/>.

```sh
mkdir -p cosmocc
cd cosmocc
wget https://cosmo.zip/pub/cosmocc/cosmocc.zip
unzip cosmocc.zip
```

Here's an example program we can write:

```c
// hello.c
#include <stdio.h>

int main() {
  printf("hello world\n");
}
```

It can be compiled as follows:

```sh
cosmocc -o hello hello.c
./hello
```

The Cosmopolitan Libc runtime links some heavyweight troubleshooting
features by default, which are very useful for developers and admins.
Here's how you can log system calls:

```sh
./hello --strace
```

Here's how you can get a much more verbose log of function calls:

```sh
./hello --ftrace
```

You can use the Cosmopolitan's toolchain to build conventional open
source projects which use autotools. This strategy normally works:

```sh
export CC=x86_64-unknown-cosmo-cc
export CXX=x86_64-unknown-cosmo-c++
./configure --prefix=/opt/cosmos/x86_64
make -j
make install
```

## Cosmopolitan Source Builds

Cosmopolitan can be compiled from source on any of our supported
platforms. The Makefile will download cosmocc automatically.

It's recommended that you install a systemwide APE Loader. This command
requires `sudo` access to copy the `ape` command to a system folder and
register with binfmt_misc on Linux, for even more performance.

```sh
ape/apeinstall.sh
```

You can now build the mono repo with any modern version of GNU Make. To
bootstrap your build, you can install Cosmopolitan Make from this site:

https://cosmo.zip/pub/cosmos/bin/make

E.g.:

```sh
curl -LO https://cosmo.zip/pub/cosmos/bin/make
./make -j8
o//examples/hello
```

After you've built the repo once, you can also use the make from your
cosmocc at `.cosmocc/current/bin/make`. You might even prefer to alias
make to `$COSMO/.cosmocc/current/bin/make`.

Since the Cosmopolitan repository is very large, you might only want to
build one particular thing. Here's an example of a target that can be
compiled relatively quickly, whi