Añadir 'lookup.sh'

With the command _host_ we don't need two files to make the resolutions

lookup.sh

@@ -0,0 +1,20 @@
+#!/bin/bash
+if [ -z "$1" ]
+then
+    echo "You must specify a filename to read from"
+    exit 1;
+fi
+if [ ! -f "$1" ]
+then
+    echo "File $1 does not exist or is not a file"
+    exit 1;
+fi
+while read ip n
+do   
+   if [ -z "$2" ]
+   then
+   echo $(host "$ip")
+   else
+   echo $(host "$ip" "$2")
+   fi   
+done < $1