Make installer work with mountpoint /var/www/html, backup pre-existing files.

installer.sh

@@ -73,9 +73,23 @@ else
   exit 1
 fi
 
+if [[ -d "$MW_DIR" && "$(ls -A "$MW_DIR")" ]]; then
+  TIMESTAMP=$(date +%Y%m%d-%H%M%S)
+  ARCHIVE_DIR="${MW_DIR}~old-${TIMESTAMP}"
+  echo "[*] Existing files detected in $MW_DIR."
+
+  mkdir -p "$ARCHIVE_DIR"
+  shopt -s dotglob nullglob
+  mv "$MW_DIR"/* "$ARCHIVE_DIR"/ 2>/dev/null || true
+  shopt -u dotglob nullglob
+
+  echo "[*] Moved existing contents to $ARCHIVE_DIR"
+fi
+if [[ ! -e "$MW_DIR" ]]; then
+  mkdir -p "$MW_DIR"
+fi
 tar -xzf "mediawiki-${MW_VERSION}.tar.gz"
-rm -rf "$MW_DIR"
-mv "mediawiki-${MW_VERSION}" "$MW_DIR"
+cp -a "mediawiki-${MW_VERSION}/." "$MW_DIR/"
 
 ### AUTO-CONFIGURE MEDIAWIKI ###
 echo "[*] Generating LocalSettings.php..."