Update backup script to start a new backup, but replace the old

gentoo-backup.sh

@@ -9,6 +9,7 @@ fi
 
 pushd /var/backup &>/dev/null || exit 2
 
+echo "Creating stage4 backup in /var/backup/$bhost-stage4.zst"
 mkstage4 -s -l -q -C zst \
     -e "/var/lib/containers/*" \
     -e "/var/lib/machines/*" \
@@ -16,6 +17,16 @@ mkstage4 -s -l -q -C zst \
     -e "/var/lib/libvirt/*" \
     -e "/var/cache/binpkgs/*" \
     -e "/home/*/*" \
-    "$bhost-stage4"
+    "$bhost-stage4-$bdate"
+
+if [[ "$?" -ne 0  ]]; then
+    echo "ERROR: Backup failure"
+    exit 1
+else
+    if [[ -f "/var/backup/$bhost-stage4.zst" ]]; then
+        rm -f "/var/backup/$bhost-stage4.zst"
+    fi
+    mv "/var/backup/$bhost-stage4-$bdate.zst" "/var/backup/$bhost-stage4.zst"
+fi
 
 popd &>/dev/null || exit 2