Add dependency checks with helpful error messages

Script now verifies required (lsblk, lspci, etc.) and optional
(smartctl, ceph, bc, nvme) dependencies at startup.

- Exits with clear error if required dependencies are missing
- Warns about missing optional dependencies with reduced functionality
- Directs users to freshStartScript for easy installation
- Checks for sudo access needed for SMART operations

Fixes: #3

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

driveAtlas.sh

@@ -5,6 +5,70 @@
 # Maps physical drive bays to logical device names using PCI paths
 #==============================================================================
 
+#------------------------------------------------------------------------------
+# Dependency Checks
+# Verifies required commands are available before running
+#------------------------------------------------------------------------------
+
+# Required dependencies (script will not function without these)
+REQUIRED_DEPS=(lsblk lspci readlink hostname)
+
+# Optional dependencies (enhanced functionality)
+OPTIONAL_DEPS=(smartctl ceph ceph-volume bc nvme)
+
+FRESH_START_URL="http://10.10.10.63:3000/LotusGuild/freshStartScript/raw/branch/main/freshStart.sh"
+
+#------------------------------------------------------------------------------
+# check_dependencies
+#
+# Verifies required and optional commands are available.
+# Exits with error if required dependencies are missing.
+# Warns about missing optional dependencies.
+#------------------------------------------------------------------------------
+check_dependencies() {
+    local missing_required=()
+    local missing_optional=()
+
+    # Check required dependencies
+    for cmd in "${REQUIRED_DEPS[@]}"; do
+        if ! command -v "$cmd" &>/dev/null; then
+            missing_required+=("$cmd")
+        fi
+    done
+
+    # Check optional dependencies
+    for cmd in "${OPTIONAL_DEPS[@]}"; do
+        if ! command -v "$cmd" &>/dev/null; then
+            missing_optional+=("$cmd")
+        fi
+    done
+
+    # Report missing required dependencies and exit
+    if [[ ${#missing_required[@]} -gt 0 ]]; then
+        echo "ERROR: Missing required dependencies: ${missing_required[*]}" >&2
+        echo "" >&2
+        echo "Please install the missing packages or run the fresh start script:" >&2
+        echo "  curl -s $FRESH_START_URL | bash" >&2
+        echo "" >&2
+        exit 1
+    fi
+
+    # Warn about missing optional dependencies
+    if [[ ${#missing_optional[@]} -gt 0 ]]; then
+        echo "Note: Some optional features unavailable. Missing: ${missing_optional[*]}" >&2
+        echo "      Install them or run: curl -s $FRESH_START_URL | bash" >&2
+        echo "" >&2
+    fi
+
+    # Check for sudo access (needed for smartctl)
+    if command -v smartctl &>/dev/null && ! sudo -n true 2>/dev/null; then
+        echo "Note: SMART data requires sudo access. Run with sudo for full functionality." >&2
+    fi
+}
+
+# Run dependency check at script start
+check_dependencies
+
 #------------------------------------------------------------------------------
 # Chassis Type Definitions
 # These define the physical layout and display formatting for each chassis type