Simpler nginx working set plugin. Replaces nginx_memory (which displays total of virtual memory)

and ngnix_memory (sic) which has a bug including non-nginx processes.

plugins/nginx/nginx_working_set

@@ -0,0 +1,24 @@
+#!/bin/bash
+#
+# Munin plugin for monitoring Nginx working set
+#
+# ---
+
+if [ "$1" == config ]; then
+    cat <<'EOF'
+graph_title NGINX Working Set
+graph_vlabel WS Bytes
+graph_category nginx
+graph_args --base 1024
+ws.label Working Set
+EOF
+    exit 0
+fi
+
+KBS=$(ps -o rss --no-heading -p $(pidof nginx))
+total=0
+for size in $KBS
+do
+    total=$(($total + $size * 1024))
+done
+echo ws.value $total