Cosmopolitan

Cosmopolitan Libc makes 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 + NetBSD + BIOS with the best possible performance and the tiniest footprint imaginable.

Background

For an introduction to this project, please read the αcτµαlly pδrταblε εxεcµταblε blog post and cosmopolitan libc website. We also have API documentation.

Getting Started

If you're doing your development work on Linux or BSD then you need just five files to get started. Here's what you do on Linux:

wget https://justine.lol/cosmopolitan/cosmopolitan-amalgamation-1.0.zip
unzip cosmopolitan-amalgamation-1.0.zip
printf 'main() { printf("hello world\\n"); }\n' >hello.c
gcc -g -Os -static -nostdlib -nostdinc -fno-pie -no-pie -mno-red-zone \
  -fno-omit-frame-pointer -pg -mnop-mcount \
  -o hello.com.dbg hello.c -fuse-ld=bfd -Wl,-T,ape.lds \
  -include cosmopolitan.h crt.o ape.o cosmopolitan.a
objcopy -S -O binary hello.com.dbg hello.com

You now have a portable program. Please note that your APE binary will assimilate itself as a conventional resident of your platform after the first run, so it can be fast and efficient for subsequent executions.

./hello.com
bash -c './hello.com'  # zsh/fish workaround (we upstreamed patches)

So if you intend to copy the binary to Windows or Mac then please do that before you run it, not after.

MacOS

If you're developing on MacOS you can install the GNU compiler collection for x86_64-elf via homebrew:

brew install x86_64-elf-gcc

Then in the above scripts just replace gcc and objcopy with x86_64-elf-gcc and x86_64-elf-objcopy to compile your APE binary.

Windows

If you're developing on Windows then you need to download an x86_64-pc-linux-gnu toolchain beforehand. See the Compiling on Windows tutorial. It's needed because the ELF object format is what makes universal binaries possible.

Source Builds

Cosmopolitan can be compiled from source on any Linux distro. GNU make needs to be installed beforehand. This is a freestanding hermetic repository that bootstraps using a vendored static gcc9 executable. No further dependencies are required.

wget https://justine.lol/cosmopolitan/cosmopolitan-1.0.tar.gz
tar xf cosmopolitan-1.0.tar.gz  # see releases page
cd cosmopolitan
make -j16
o//examples/hello.com
find o -name \*.com | xargs ls -rShal | less

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