gpt-4 turbo's attempt at a distro-agnostic build script. tested only on debian and alpine. takes tarball path as argument

build_linux.sh

#!/bin/bash

# Exit on errors and unset variables
set -euo pipefail

# Function to detect package manager and install packages
install_packages() {
    local debian_packages=(build-essential libncurses-dev bison flex libssl-dev libelf-dev dwarves)
    local redhat_packages=(make gcc ncurses-devel bison flex openssl-devel elfutils-libelf-devel pahole)
    local suse_packages=(make gcc ncurses-devel bison flex libopenssl-devel libelf-devel dwarves)
    local arch_packages=(base-devel ncurses bison flex openssl elfutils pahole)
    local alpine_packages=(build-base ncurses-dev bison flex openssl-dev elfutils-dev dwarves)

    if command -v apt-get &>/dev/null; then
        sudo apt-get update
        sudo apt-get install -y "${debian_packages[@]}"
    elif command -v dnf &>/dev/null; then
        sudo dnf install -y "${redhat_packages[@]}"
    elif command -v yum &>/dev/null; then
        sudo yum install -y "${redhat_packages[@]}"
    elif command -v zypper &>/dev/null; then
        sudo zypper install -y "${suse_packages[@]}"
    elif command -v pacman &>/dev/null; then
        sudo pacman -Sy --needed "${arch_packages[@]}"
    elif command -v apk &>/dev/null; then
        sudo apk add --update "${alpine_packages[@]}"
    else
        echo "Unsupported package manager. Install the required packages manually."
        exit 1
    fi
}

# Check if a tarball path was provided as an argument
if [ $# -eq 0 ]; then
    echo "Usage: $0 <path/to/linux-x.y.z.tar.xz>"
    exit 1
fi

TARBALL="$1"

# Check if the kernel tarball exists
if [ ! -f "${TARBALL}" ]; then
    echo "The kernel tarball ${TARBALL} does not exist. Please provide the correct path."
    exit 1
fi

# Install required packages for building the kernel
install_packages

# Extract the kernel version from the tarball name
KERNEL_VERSION=$(basename "${TARBALL}" .tar.xz | sed 's/linux-//')

# Unpack the kernel source and move into the directory
tar -xvf "${TARBALL}"
cd "linux-${KERNEL_VERSION}"

# Copy current config if available
if [ -f "/boot/config-$(uname -r)" ]; then
    cp -v "/boot/config-$(uname -r)" .config
else
    echo "No config found in /boot. Default config will be used."
fi

# Use old config and set new version
yes '' | make oldconfig

# Compile the kernel with default options
make -j"$(nproc)"

# Strip symbols from modules to save space
make INSTALL_MOD_STRIP=1 modules_install

# Install the kernel
sudo make install

# Strip the kernel image if it exists
if [ -f "/boot/vmlinuz-${KERNEL_VERSION}" ]; then
    sudo strip --strip-debug "/boot/vmlinuz-${KERNEL_VERSION}"
fi

# Update bootloader
if command -v update-grub &>/dev/null; then
    sudo update-grub
elif command -v grub2-mkconfig &>/dev/null; then
    sudo grub2-mkconfig -o /boot/grub2/grub.cfg
elif command -v grub-mkconfig &>/dev/null; then
    sudo grub-mkconfig -o /boot/grub/grub.cfg
else
    echo "Bootloader update command not found. Update bootloader manually."
fi

# Prompt for reboot
read -p "Kernel installation is complete. Would you like to reboot now? [y/N] " response
if [[ "$response" =~ ^([yY][eE][sS]|[yY])$ ]]; then
    sudo reboot
fi