install-go

install-go.sh

#!/usr/bin/env bash
set -euo pipefail

msg() { printf '%s\n' "$*"; }
warn() { printf '⚠️  %s\n' "$*" >&2; }
die() {
    printf '❌ %s\n' "$*" >&2
    exit 1
}

# -------- Colors --------
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

# -------- Linux only --------
OS="$(uname -s | tr '[:upper:]' '[:lower:]')"
[ "$OS" = "linux" ] || die "Linux only. Detected: $(uname -s)"

# -------- sudo/root handling --------
if command -v sudo >/dev/null 2>&1; then
    SUDO="sudo"
else
    SUDO=""
fi
if [ "$(id -u)" -ne 0 ] && [ -z "$SUDO" ]; then
    die "Need root or sudo to auto-install missing commands and install Go to /usr/local."
fi

# -------- detect package manager --------
detect_pm() {
    if command -v apt-get >/dev/null 2>&1; then
        echo "apt"
        return
    fi
    if command -v dnf >/dev/null 2>&1; then
        echo "dnf"
        return
    fi
    if command -v yum >/dev/null 2>&1; then
        echo "yum"
        return
    fi
    if command -v pacman >/dev/null 2>&1; then
        echo "pacman"
        return
    fi
    if command -v apk >/dev/null 2>&1; then
        echo "apk"
        return
    fi
    if command -v zypper >/dev/null 2>&1; then
        echo "zypper"
        return
    fi
    echo "unknown"
}

PM="$(detect_pm)"
[ "$PM" != "unknown" ] || die "No supported package manager found (apt/dnf/yum/pacman/apk/zypper). Install dependencies manually: curl tar awk"

install_pkgs() {
    # shellcheck disable=SC2086
    case "$PM" in
    apt)
        $SUDO apt-get update -y
        $SUDO apt-get install -y "$@"
        ;;
    dnf)
        $SUDO dnf install -y "$@"
        ;;
    yum)
        $SUDO yum install -y "$@"
        ;;
    pacman)
        $SUDO pacman -Sy --noconfirm "$@"
        ;;
    apk)
        $SUDO apk add --no-cache "$@"
        ;;
    zypper)
        $SUDO zypper --non-interactive install "$@"
        ;;
    esac
}

# Map command -> package name(s) per distro family
ensure_cmd() {
    local cmd="$1"
    if command -v "$cmd" >/dev/null 2>&1; then
        return 0
    fi

    msg "🔧 Missing '$cmd' — installing…"

    case "$cmd" in
    curl)
        case "$PM" in
        apt | dnf | yum | pacman | apk | zypper) install_pkgs curl ;;
        esac
        ;;
    tar)
        case "$PM" in
        apt | dnf | yum | pacman | apk | zypper) install_pkgs tar ;;
        esac
        ;;
    awk)
        # awk is usually in gawk (or mawk) depending on distro
        case "$PM" in
        apt) install_pkgs gawk ;;
        dnf | yum) install_pkgs gawk ;;
        pacman) install_pkgs gawk ;;
        apk) install_pkgs gawk ;;
        zypper) install_pkgs gawk ;;
        esac
        ;;
    *)
        die "Don't know how to install missing command: $cmd"
        ;;
    esac

    command -v "$cmd" >/dev/null 2>&1 || die "Failed to install '$cmd'. Please install it manually."
}

# -------- ensure prerequisites (auto-install) --------
ensure_cmd curl
ensure_cmd tar
ensure_cmd awk

# -------- architecture --------
M="$(uname -m)"
case "$M" in
x86_64 | amd64) ARCH="amd64" ;;
aarch64 | arm64) ARCH="arm64" ;;
i386 | i686) ARCH="386" ;;
*) die "Unsupported architecture: $M" ;;
esac

# -------- shell rc --------
detect_shell_rc() {
    # Check current shell
    case "$SHELL" in
    */zsh) echo "$HOME/.zshrc" ;;
    */fish) echo "$HOME/.config/fish/config.fish" ;;
    *) echo "$HOME/.bashrc" ;;
    esac
}

SHELL_RC="$(detect_shell_rc)"
INSTALL_DIR="/usr/local"
GO_BIN="$INSTALL_DIR/go/bin"

# -------- latest Go version --------
msg "🔍 Fetching latest Go version..."
GO_VERSION_FULL="$(curl -fsSL 'https://go.dev/VERSION?m=text' | awk 'NR==1{print; exit}')"
[ -n "$GO_VERSION_FULL" ] || die "Could not determine latest Go version."

# -------- check if already installed --------
if [ -x "$GO_BIN/go" ]; then
    CURRENT_VERSION="$("$GO_BIN/go" version 2>/dev/null | awk '{print $3}')" || CURRENT_VERSION=""
    if [ "$CURRENT_VERSION" = "$GO_VERSION_FULL" ]; then
        msg "✅ Go $GO_VERSION_FULL is already installed and up to date"
        "$GO_BIN/go" version
        exit 0
    fi
    msg "🔄 Upgrading from $CURRENT_VERSION to $GO_VERSION_FULL"
else
    msg "📦 Installing Go $GO_VERSION_FULL"
fi

GO_TAR="${GO_VERSION_FULL}.linux-${ARCH}.tar.gz"
URL="https://go.dev/dl/${GO_TAR}"
CHECKSUM_URL="https://go.dev/dl/?mode=json"

msg ""
msg "🔹 OS:      linux"
msg "🔹 ARCH:    $ARCH"
msg "🔹 Go:      $GO_VERSION_FULL"
msg "🔹 URL:     $URL"
msg "🔹 RC file: $SHELL_RC"
msg ""

# -------- download & install --------
TMPDIR="$(mktemp -d)"
trap 'rm -rf "$TMPDIR"' EXIT
cd "$TMPDIR"

msg "⬇️  Downloading Go..."
curl -fL --retry 3 --progress-bar -O "$URL"

# -------- checksum verification --------
msg "🔐 Verifying checksum..."
EXPECTED_SHA256="$(curl -fsSL "$CHECKSUM_URL" |
    awk -v fname="$GO_TAR" '
    BEGIN { RS="[{},]"; FS=":" }
    /"filename"/ { gsub(/[" ]/, "", $2); file=$2 }
    /"sha256"/ { gsub(/[" ]/, "", $2); sha=$2 }
    file == fname && sha { print sha; exit }
    ')"

if [ -n "$EXPECTED_SHA256" ]; then
    ACTUAL_SHA256="$(sha256sum "$GO_TAR" | awk '{print $1}')"
    if [ "$EXPECTED_SHA256" = "$ACTUAL_SHA256" ]; then
        msg "✅ Checksum verified"
    else
        die "Checksum mismatch! Expected: $EXPECTED_SHA256, Got: $ACTUAL_SHA256"
    fi
else
    warn "Could not fetch checksum, skipping verification"
fi

# -------- verify archive --------
msg "📂 Verifying archive..."
tar -tzf "$GO_TAR" >/dev/null || die "Archive verification failed"

# -------- install --------
msg "📥 Installing to $INSTALL_DIR..."
$SUDO rm -rf "$INSTALL_DIR/go"
$SUDO tar -C "$INSTALL_DIR" -xzf "$GO_TAR"

# -------- PATH and environment update (idempotent) --------
msg "🔧 Configuring environment..."

setup_shell_env() {
    local rc_file="$1"
    local is_fish=false
    [[ "$rc_file" == *"fish"* ]] && is_fish=true

    touch "$rc_file"

    if [ "$is_fish" = true ]; then
        # Fish shell syntax
        local go_path_entry="set -gx PATH $GO_BIN \$PATH"
        local gopath_entry='set -gx GOPATH $HOME/go'
        local gobin_entry='set -gx PATH $GOPATH/bin $PATH'

        if ! grep -q "set -gx PATH $GO_BIN" "$rc_file" 2>/dev/null; then
            printf '\n# Go installation\n%s\n%s\n%s\n' "$go_path_entry" "$gopath_entry" "$gobin_entry" >>"$rc_file"
            msg "✅ Environment updated in $rc_file"
        else
            msg "🔹 Environment already configured in $rc_file"
        fi
    else
        # Bash/Zsh syntax
        local go_path_entry="export PATH=\"${GO_BIN}:\$PATH\""
        local gopath_entry='export GOPATH="$HOME/go"'
        local gobin_entry='export PATH="$GOPATH/bin:$PATH"'

        if ! grep -q "export PATH=\"${GO_BIN}" "$rc_file" 2>/dev/null; then
            printf '\n# Go installation\n%s\n%s\n%s\n' "$go_path_entry" "$gopath_entry" "$gobin_entry" >>"$rc_file"
            msg "✅ Environment updated in $rc_file"
        else
            msg "🔹 Environment already configured in $rc_file"
        fi
    fi
}

setup_shell_env "$SHELL_RC"

# -------- create GOPATH directory --------
mkdir -p "$HOME/go/bin" "$HOME/go/src" "$HOME/go/pkg"

# -------- verify installation --------
msg ""
msg "=================================================="
msg "   Go Installation Complete"
msg "=================================================="
msg ""
"$GO_BIN/go" version
msg ""
msg "📍 Go binary:  $GO_BIN/go"
msg "📍 GOPATH:     \$HOME/go"
msg "📍 Shell RC:   $SHELL_RC"
msg ""
msg "ℹ️  Restart your shell or run:"
msg "   source \"$SHELL_RC\""
msg ""