# Download the Fuchsia source code

This guide provides instructions on how to download the
Fuchsia source code and set up the Fuchsia development
environment on your machine.

The steps are:

1. [Install prerequisite packages](#install-prerequisite-packages).
2. [Perform a preflight check](#perform-a-preflight-check).
3. [Download the Fuchsia source code](#download-the-fuchsia-source-code).
4. [Set up environment variables](#set-up-environment-variables).
5. [Configure firewall rules (Optional)](#configure-firewall-rules).


## 1. Install prerequisite packages {#install-prerequisite-packages}

Fuchsia requires `curl`, `file`, `unzip`, and `git` to be up to date.
The version of `git` needs to be 2.31 or higher.

Install (or update) the following packages:

```posix-terminal
sudo apt install curl file git unzip
```

## 2. Perform a preflight check {#perform-a-preflight-check}

Fuchsia provides a preflight check tool
([`ffx platform preflight`][ffx-platform-preflight])
that examines your machine and informs you of any issues that may
affect building Fuchsia from source on the machine.

Note: The preflight tool only works for the x64 architecture.

Run the following command:

```posix-terminal
curl -sO https://storage.googleapis.com/fuchsia-ffx/ffx-linux-x64 && chmod +x ffx-linux-x64 && ./ffx-linux-x64 platform preflight
```

## 3. Download the Fuchsia source code {#download-the-fuchsia-source-code}

Fuchsia provides a [bootstrap script](/scripts/bootstrap) that creates a
directory named `fuchsia` and downloads the Fuchsia source code in that
directory.

Downloading the Fuchsia source code requires about 2 GB of space
on your machine. Depending on your build configuration, you need
another 80 to 90 GB of space later when you build Fuchsia. Additionally,
the download process uses a substantial amount of memory. It is advisible
to close non-crucial processes during this time.

To download the Fuchsia source, do the following:

1.  Select a directory for downloading the Fuchsia source code, for example:

    Note: You can set up Fuchsia in any directory. This guide selects
    the `$HOME` directory as an example.

    ```posix-terminal
    cd $HOME
    ```

1.  Run the bootstrap script:

    Note: Depending on your network speed, downloading the Fuchsia source code
    (which is about 2 GB) can take a while.

    ```posix-terminal
    curl -s "https://fuchsia.googlesource.com/fuchsia/+/HEAD/scripts/bootstrap?format=TEXT" | base64 --decode | bash
    ```
    This script creates the `fuchsia` directory and downloads the source code.

    If you see the `Invalid authentication credentials` error during the
    bootstrapping process, see [Authentication error](#authentication-error) for
    help.

    If you have a slower internet connection and run into timeouts, you may wish
    to download the bootstrap script directly and increase the values of
    `-fetch-packages-timeout` and `-hook-timeout`. These timeouts are in
    minutes, and indicate a 2 hour timeout for package downloads. (The
    `-hook-timeout` value is multiplied by 5 when downloading CIPD packages.)

## 4. Set up environment variables {#set-up-environment-variables}

Note: If you don't wish to update your shell profile, see
[Work on Fuchsia without updating your PATH](#work-on-fuchsia-without-updating-your-path)
in Appendices instead.

To configure the recommended Fuchsia environment variables in your shell profile,
do the following:

1.  Use a text editor to open your `~/.bash_profile` file (in the example below,
    we use the [Nano][nano]{:.external} text editor):

    Note: This guide uses a `bash` terminal as an example. If you're
    using `zsh`, replace `~/.bash_profile` with `~/.zprofile` in the
    following steps.

    ```posix-terminal
    nano ~/.bash_profile
    ```

1.  Add the following lines to your `~/.bash_profile` file:

    Note: If your Fuchsia source code is not located in the `~/fuchsia`
    directory, replace `~/fuchsia` with your Fuchsia directory.

    ```sh
    export PATH=~/fuchsia/.jiri_root/bin:$PATH
    source ~/fuchsia/scripts/fx-env.sh
    ```

    *   The `.jiri_root/bin` directory in the Fuchsia source contains the
        [`jiri`](https://fuchsia.googlesource.com/jiri) and
        [`fx`](/docs/development/build/fx.md) tools that are essential to
        Fuchsia workflows. Fuchsia uses the `jiri` tool to manage repositories in
        the Fuchsia project, and the `fx` tool helps configure, build, run, and
        debug Fuchsia. The Fuchsia toolchain requires that `jiri` is available in
        your `PATH`.

    *   The [`fx-env.sh`](/scripts/fx-env.sh) script enables a number of
        useful shell functions in your terminal. For instance, it creates the
        `FUCHSIA_DIR` environment variable and provides the `fd` command for
        navigating directories with auto-completion. (For more information, see
        comments in `fx-env.sh`.)

1.  Save the file and exit the text editor.

1.  To update your environment variables, run the following command:

    ```posix-terminal
    source ~/.bash_profile
    ```

1.  Verify your environment setup:

    1. Go to your `fuchsia` directory, for example:

       ```posix-terminal
       cd ~/fuchsia
       ```

    2. Verify that you can run the following commands without errors:

       ```posix-terminal
       jiri help
       ```

       ```posix-terminal
       fx help
       ```

## 5. Configure firewall rules (Optional) {#configure-firewall-rules}

Note: This step is not required for building or running Fuchsia. But it is
recommended to ensure that Fuchsia's emulator instances run smoothly on Linux.

Run the following command to allow Fuchsia-specific traffic on the host machine:

```posix-terminal
fx setup-ufw
```

This script requires `sudo` (which asks for your password) to set the appropriate
firewall rules. (For more information on this script, see [`setup-ufw`][setup-ufw].)

## Next steps

To build your first Fuchsia system image, see
[Configure and build Fuchsia](/docs/get-started/build_fuchsia.md).

## Appendices

### Authentication error {#authentication-error}

If you see the `Invalid authentication credentials` error during the bootstrap
process, your `~/.gitcookies` file may contain cookies from some repositories in
`googlesource.com` that the bootstrap script wants to check out anonymously.

To resolve this error, do one of the following:

*   Follow the onscreen directions to get passwords for the specified
    repositories.
*   Delete the offending cookies from the `.gitcookies` file.

### Work on Fuchsia without updating your PATH {#work-on-fuchsia-without-updating-your-path}

The following sections provide alternative approaches to the
[Set up environment variables](#set-up-environment-variables) section:

*   [Copy the tool to your binary directory](#copy-the-tool-to-your-binary-directory)
*   [Add a symlink to your binary directory](#add-a-symlink-to-your-binary-directory)

#### Copy the tool to your binary directory {#copy-the-tool-to-your-binary-directory}

If you don't wish to update your environment variables, but you want `jiri` to
work in any directory, copy the `jiri` tool to your `~/bin` directory, for
example:

Note: If your Fuchsia source code is not located in the `~/fuchsia` directory,
replace `~/fuchsia` with your Fuchsia directory.

```posix-terminal
cp ~/fuchsia/.jiri_root/bin/jiri ~/bin
```

However, you must have write access to the `~/bin` directory without `sudo`. If
you don't, `jiri` cannot keep itself up-to-date.

#### Add a symlink to your binary directory {#add-a-symlink-to-your-binary-directory}

Similarly, if you want to use the `fx` tool without updating your environment
variables, provide the `fx` tool's symlink in your `~/bin` directory, for
example:

Note: If your Fuchsia source code is not located in the `~/fuchsia` directory,
replace `~/fuchsia` with your Fuchsia directory.

```posix-terminal
ln -s ~/fuchsia/scripts/fx ~/bin
```

Alternatively, run the `fx` tool directly using its path, for example:

```posix-terminal
./scripts/fx help
```

In either case, you need `jiri` in your `PATH`.

<!-- Reference links -->

[ffx-platform-preflight]: https://fuchsia.dev/reference/tools/sdk/ffx#preflight
[nano]: https://www.nano-editor.org/docs.php
[setup-ufw]: https://fuchsia.dev/reference/tools/fx/cmd/setup-ufw