Installs a Go release tarball (e.g. go1.25.6.linux-amd64.tar.gz) in the `~/.local` folder following the XDG specification for user apps.

install-go.sh

#!/bin/bash
#
# Installs a Go tarball to ~/.local/share/go/<version> and symlinks binaries to ~/.local/bin
#
# Usage: ./install-go.sh [options] <go-tarball>
# Example: ./install-go.sh go1.24.2.linux-amd64.tar.gz

set -euo pipefail

GO_BASE_DIR="$HOME/.local/share/go"
BIN_DIR="$HOME/.local/bin"
FORCE=false

# Print error message and exit
die() {
    echo "Error: $1" >&2
    exit 1
}

# Print help message
show_help() {
    cat <<EOF
Usage: $0 [options] <go-tarball>

Installs a Go tarball to ~/.local/share/go/<version> and symlinks binaries
to ~/.local/bin.

Arguments:
  <go-tarball>    Path to a Go release tarball (e.g., go1.24.2.linux-amd64.tar.gz)

Options:
  -h, --help      Show this help message and exit
  -f, --force     Remove existing installation of the same version before installing.
                  Without this flag, the script will exit with an error if the
                  version is already installed.

Examples:
  $0 go1.24.2.linux-amd64.tar.gz
  $0 --force go1.24.2.linux-amd64.tar.gz

EOF
    exit 0
}

# Print usage and exit
usage() {
    echo "Usage: $0 [options] <go-tarball>"
    echo ""
    echo "Options:"
    echo "  -h, --help    Show help message"
    echo "  -f, --force   Remove existing version before installing"
    echo ""
    echo "Example: $0 go1.24.2.linux-amd64.tar.gz"
    exit 1
}

# Extract version from tarball filename (e.g., "go1.24.2.linux-amd64.tar.gz" -> "1.24.2")
extract_version() {
    local filename="$1"
    local basename
    basename=$(basename "$filename")

    if [[ "$basename" =~ ^go([0-9]+\.[0-9]+(\.[0-9]+)?)\. ]]; then
        echo "${BASH_REMATCH[1]}"
    else
        die "Could not extract version from filename: $basename"
    fi
}

# Main
main() {
    local tarball=""

    # Parse arguments
    while [[ $# -gt 0 ]]; do
        case "$1" in
            -h|--help)
                show_help
                ;;
            -f|--force)
                FORCE=true
                shift
                ;;
            -*)
                die "Unknown option: $1. Use --help for usage information."
                ;;
            *)
                if [[ -n "$tarball" ]]; then
                    die "Multiple tarballs specified. Use --help for usage information."
                fi
                tarball="$1"
                shift
                ;;
        esac
    done

    if [[ -z "$tarball" ]]; then
        usage
    fi

    # Validate tarball exists and is readable
    if [[ ! -f "$tarball" ]]; then
        die "File not found: $tarball"
    fi

    if [[ ! -r "$tarball" ]]; then
        die "File not readable: $tarball"
    fi

    # Validate it's a gzipped tar
    if [[ "$tarball" != *.tar.gz && "$tarball" != *.tgz ]]; then
        die "Expected a .tar.gz or .tgz file, got: $tarball"
    fi

    # Extract version
    local version
    version=$(extract_version "$tarball")
    echo "Detected Go version: $version"

    local install_dir="$GO_BASE_DIR/$version"

    # Check if version already installed
    if [[ -d "$install_dir" ]]; then
        if [[ "$FORCE" == true ]]; then
            echo "Removing existing installation at $install_dir..."
            rm -rf "$install_dir"
        else
            die "Version $version already installed at $install_dir. Use --force to reinstall."
        fi
    fi

    # Create directories
    echo "Creating directories..."
    mkdir -p "$GO_BASE_DIR"
    mkdir -p "$BIN_DIR"

    # Create temp directory for extraction
    local tmpdir
    tmpdir=$(mktemp -d)
    trap 'rm -rf "$tmpdir"' EXIT

    # Extract tarball to temp directory
    echo "Extracting $tarball..."
    if ! tar -C "$tmpdir" -xzf "$tarball"; then
        die "Failed to extract tarball"
    fi

    # Verify extraction produced a 'go' directory
    if [[ ! -d "$tmpdir/go" ]]; then
        die "Tarball did not contain expected 'go' directory"
    fi

    # Move to final location
    echo "Installing to $install_dir..."
    mv "$tmpdir/go" "$install_dir"

    # Symlink binaries
    echo "Creating symlinks in $BIN_DIR..."
    local bin_path="$install_dir/bin"
    if [[ ! -d "$bin_path" ]]; then
        die "No bin directory found at $bin_path"
    fi

    for binary in "$bin_path"/*; do
        if [[ -x "$binary" ]]; then
            local name
            name=$(basename "$binary")
            local link="$BIN_DIR/$name"

            if [[ -e "$link" || -L "$link" ]]; then
                echo "  Replacing existing: $name"
                rm -f "$link"
            else
                echo "  Linking: $name"
            fi

            ln -s "$binary" "$link"
        fi
    done

    echo ""
    echo "Go $version installed successfully!"
    echo ""
    echo "Make sure $BIN_DIR is in your PATH. Add to ~/.bashrc if needed:"
    echo "  export PATH=\"\$HOME/.local/bin:\$PATH\""
    echo ""
    echo "Verify with: go version"
}

main "$@"