Mastering the Nmap Scripting Engine

Exploring environment variables

There are a few environment variables that you need to consider when writing scripts because they will be helpful:

• SCRIPT_PATH: This returns the absolute path of the running script
• SCRIPT_NAME: This returns the running script name
• SCRIPT_TYPE: This returns "prerule", "hostrule", "portrule", or "postrule"

Use the SCRIPT_NAME environment variable instead of hardcoding the name of your script. This way, you won't need to update the script if you end up changing its name. For example, you could use it to read script arguments as follows:

local arg1 = stdnse.get_script_args(SCRIPT_NAME..".arg1")

The stdnse library will be explored later in this chapter. This library contains the get_script_args() function that can be used ...