title: Calling variable within sed command syntax
body: <p>I'm creating a script to more easily allow my organization to add workstations to our Nagios monitoring system. </p>
  
  <p>Each time the script runs, I'd like to be able to input the hostname, alias,and address, ( as variables input by user ) and have those variables called WITHIN the sed command so as to "create" a new host much faster then typing it all out. </p>
  
  <p>I'm attempting to add the entire string AFTER sed finds 
  " address of the host }"</p>
  
  <p>which i assumed was /a ( append after it finds said string )
  Still,  using double quotes hasn't allowed the variables to be called.</p>
  
  <pre><code>#!bin/bash
  
  # Prompt for hostname, alias, and IP address of new host
  # take user input has variable to be used in sed 
  
  # Takes user input for hostname
  echo host_name : 
  read var_hostname    
  # Takes user input for alias
  echo alias : 
  read var_alias
  # Takes user input for ip address
  echo address : 
  read var_address
  # searches for the top-most instance "address of the host" within the     windows.cfg file
  # after said instance is found, appends the new string below, which calls     for the variables received 
  # previously by user
  sed -i -e  " address of the host } /a 
  define host{
      use             windows-server  ; Inherit default values from a     template
      host_name       $var_hostname       ; The name we are giving to this     host
      alias           $var_alias       ; A longer name associated with the host
      address         $var_address     ; IP address of the host
      }" 
      windows.cfg        
  </code></pre>
  
  <p>I want the string "define host{}" to be written to the file with the variables the user put in. Instead </p>