qmk_firmware/util/install/gentoo.sh

#!/bin/bash

_qmk_install_prepare() {
    echo "This script will make a USE change in order to ensure that that QMK works on your system."
    echo "All changes will be sent to the file /etc/portage/package.use/qmkfirmware -- please review it, and read Portage's output carefully before installing any packages on your system."
    echo "You will also need to ensure that your kernel is compiled with support for the microcontroller that you are using (e.g. enable Arduino for the Pro Micro). Further information can be found on the Gentoo wiki."

    read -p "Proceed? [y/N] " res
    case $res in
        [Yy]*)
            return 0;;
        *)
            return 1;;
    esac
}

_qmk_install() {
    echo "Installing dependencies"

    sudo touch /etc/portage/package.use/qmkfirmware
    # tee is used here since sudo doesn't apply to >>
    echo "sys-devel/gcc multilib" | sudo tee --append /etc/portage/package.use/qmkfirmware >/dev/null
    sudo emerge -auN sys-devel/gcc
    sudo emerge -au --noreplace \
        app-arch/unzip app-arch/zip net-misc/wget sys-devel/clang sys-devel/crossdev \
        \>=dev-lang/python-3.7 \
        dev-embedded/avrdude dev-embedded/dfu-programmer app-mobilephone/dfu-util

    sudo crossdev -s4 --stable --g \<9 --portage --verbose --target avr
    sudo crossdev -s4 --stable --g \<9 --portage --verbose --target arm-none-eabi

    python3 -m pip install --user -r $QMK_FIRMWARE_DIR/requirements.txt
}