Run search with no query by default

zet

@@ -129,14 +129,7 @@ get_title_from_file() {
 }
 
 main() {
-  COMMAND="$1"
-
-  if [[ -z "$COMMAND" ]]; then
-    show_usage
-    exit 1
-  fi
-
-  case "$COMMAND" in
+  case "$1" in
     create | c)
       shift 1
       cmd_create "$@"
@@ -211,7 +204,10 @@ search_zettel() {
 
   QUERY="$*"
 
-  git grep -i --name-only --word-regex "$QUERY" | grep -o -E '[0-9]+' | sort -un
+  grep_args=("--extended-regexp")
+  [[ "$QUERY" != "" ]] && grep_args+=("--word-regex")
+
+  git grep -i --name-only "${grep_args[@]}" "$QUERY" | grep -o -E '[0-9]+' | sort -un
 }
 
 select_zet() {