Improve script a bit

wiki.sh

@@ -2,20 +2,23 @@
 PAGE=${REQUEST_URI#/}
 if [ -z $PAGE ]
 then
-  PAGE=Home
+  PAGE=$INDEX
 fi
 
+http_header () {
+  echo HTTP/1.0 $@
+  echo
+}
+
 pandoc="pandoc -f gfm -t html -s --template=$TEMPLATE -V title-prefix:$SITE_TITLE -V pagetitle:$PAGE"
 
-git show HEAD:"$PAGE".md > /dev/null
+git cat-file -e HEAD:"$PAGE".md
 
 if [ $? == 0 ]
 then
-  echo HTTP/1.0 200 OK
-  echo
+  http_header 200 OK
   git show HEAD:"$PAGE".md | $pandoc
 else
-  echo HTTP/1.0 404 Not found
-  echo
+  http_header 404 Not found
   echo "This page does not exist. [Click here]($REPO_URL/wiki/$PAGE?action=_new) to create it." | $pandoc
 fi