nginx_error: improve readability of array accesses

plugins/nginx/nginx_error

@@ -103,34 +103,30 @@ http_codes[503]='Service Unavailable'
 
 # parse error counts from log file
 do_ () {
-  local k values
+  local count status_code
   declare -A line_counts
-  values=$(awk '{print $9}' "$log" | sort | uniq -c)
-  if [ -n "$values" ]; then
-    while read -r line; do
-      read -r -a tmp <<< "$line"
-      line_counts[${tmp[1]}]=${tmp[0]}
-    done <<< "$values"
-  fi
+  while read -r count status_code; do
+      line_counts[$status_code]=$count
+  done <<< "$(awk '{print $9}' "$log" | sort | uniq -c)"
 
-  for k in "${!http_codes[@]}"; do
-    echo "error$k.value ${line_counts[$k]:-0}"
+  for status_code in "${!http_codes[@]}"; do
+    echo "error${status_code}.value ${line_counts[$status_code]:-0}"
   done
   exit 0
 }
 
 
 do_config () {
-  local k
+  local status_code
   echo "graph_title $(basename "$log") - Nginx errors per minute"
   echo "graph_vlabel pages with http error codes / \${graph_period}"
   echo "graph_category webserver"
   echo "graph_period minute"
   echo "graph_info This graph shows nginx error amount per minute"
-  for k in "${!http_codes[@]}"; do
-    echo "error$k.type DERIVE"
-    echo "error$k.min 0"
-    echo "error$k.label $k ${http_codes[$k]}"
+  for status_code in "${!http_codes[@]}"; do
+    echo "error${status_code}.type DERIVE"
+    echo "error${status_code}.min 0"
+    echo "error${status_code}.label $status_code ${http_codes[$status_code]}"
   done
   exit 0
 }