Manually Building Emscripten on Linux

This page contains basic instructions on how to manually build and configure Emscripten from source on a clean (Ubuntu 14.04.1 LTS 64bit) Linux box.

Note

The instructions clone from the main Emscripten repository (https://github.com/kripken/emscripten). Contributors should instead clone from their own Emscripten fork, and submit changes as pull requests.

Tip

You can also build Emscripten from source using the SDK. This is recommended if you need easily switch between SDK and source builds.

What you’ll need

The specific versions of tools that are needed are listed in the Emscripten Toolchain Requirements.

Installing required tools

These instructions explain how to install all the required tools. You can test whether some of these are already installed on the platform and skip those steps.

  1. Update the system package manager to ensure the package lists are up to date:

    sudo apt-get update

  2. Install Python using the system package manager:

    sudo apt-get install python2.7

  3. Install node.js using the system package manager:

    sudo apt-get install nodejs

  4. Install gcc and cmake using the system package manager:

    sudo apt-get install build-essential
sudo apt-get install cmake

  5. Install git using the system package manager:

    sudo apt-get install git-core

  6. Install Java using the system package manager:

    sudo apt-get install default-jre

  7. Build Fastcomp (LLVM + Clang) from source using these instructions.

  8. Clone the kripken/emscripten repository from Github. This repository contains the main compiler tool for compiling C/C++ programs to JavaScript:

    • Create a directory (with no spaces in the name) to contain the clone.

    • Enter the following command into the terminal:

      git clone https://github.com/kripken/emscripten.git

Configuring Emscripten settings

Almost all the compiler settings used by Emscripten are defined in the compiler configuration file (~/.emscripten), a user-specific file located in the user’s home directory.

Instructions for creating and manually configuring up this file are given in Configuring Emscripten Settings when Manually Building from Source.

Validating the environment

The best way to validate the environment is to build some code. Open the terminal in your Emscripten directory (where emcc is located) and enter:

./emcc tests/hello_world.cpp

If this builds a.out.js in the current directory, and you don’t see any build errors in the terminal, Emscripten is good to go!

There are additional validation and troubleshooting instructions in the topic: Verifying the Emscripten Development Environment.