zfs_arc_max reads 0 by default, so the fallback never fired and the ARC section divided by zero

Monitors/zfs_memory_snapshot.sh

@@ -261,8 +261,17 @@ echo "━━━ $ICON_ZFS ARC Statistics ━━━"
 if [[ ! -f /proc/spl/kstat/zfs/arcstats ]]; then
     warn "ZFS arcstats not available — skipping ARC section"
 else
-    ARC_MAX=$(cat /sys/module/zfs/parameters/zfs_arc_max 2>/dev/null || \
-              awk '/^c_max / {print $3}' /proc/spl/kstat/zfs/arcstats)
+    # zfs_arc_max reads 0 when it has been left at the default, which is a value rather than a
+    # failure — so the || fallback never fires for the case that actually needs it, exactly like a
+    # grep -c that prints 0 and exits 1. Zero here would reach the ARC_PCT division below, and awk
+    # treats division by zero as fatal: it prints nothing, ARC_PCT comes back empty, and the whole
+    # ARC section reports blanks. c_max is the cap the kernel is really enforcing either way.
+    ARC_MAX=$(cat /sys/module/zfs/parameters/zfs_arc_max 2>/dev/null || echo 0)
+    ARC_MAX="${ARC_MAX//[^0-9]/}"
+    if [[ "${ARC_MAX:-0}" -eq 0 ]]; then
+        ARC_MAX=$(awk '/^c_max / {print $3}' /proc/spl/kstat/zfs/arcstats 2>/dev/null)
+        ARC_MAX="${ARC_MAX:-0}"
+    fi
     ARC_SIZE=$(awk '/^size / {print $3}' /proc/spl/kstat/zfs/arcstats)
     ARC_META_USED=$(awk '/^arc_meta_used / {print $3}' /proc/spl/kstat/zfs/arcstats)