How can I create an Augeas lens that will allow me to extract a value field from within a parenthesis?


I'm starting an Augeas lens for managing NASL files for OpenVAS. I need to be able to make a few arbitrary changes to a large number of these scripts.

NASLs contains a lot of key and value pairs which are all surrounded by parentheses as shown below, sometimes with multiple values.

This is a sample line I'm working with. I'm not using any line breaks, comments, etc in my test script yet. The line here is exactly what I'm using.


The basic format I'm trying to use for the extraction is:

let digits = store /\d+/
let oparen = Util.del_str "("
let cparen = Util.del_str ")"
(* script_id(100197); *)
let script_id = [  key "script_id" .  oparen  . digits . cparen  ]

And the resulting error from augparse is:

Error encountered at 1:0 (0 characters into string)

Tree generated so far:

The first question you need to ask is which tree you want to produce from this string. How do you expect Augeas to parse script_id(100197).

Assuming you want to parse it as, e.g.:

{ "script_id" = "100197" }

you could parse this with the following code:

let script_id =
     let oparen = Util.del_str "("
  in let cparen = Util.del_str ")"
  in [ key "script_id"
     . oparen . store Rx.integer . cparen
     . Util.eol ]

You can add a unit test to check that it works:

test script_id get "script_id(100197)\n" = ?

and launching augparse on the file:

$ augparse openvas.aug 
Test result: openvas.aug:10.0-.44:
  { "script_id" = "100197" }

Note that Augeas only supports POSIX basic regular expressions, so \d is not recognized.

  • You have come to my aid several times on these augeas issues. Many thanks. – Tim Brigham Jan 3 '14 at 19:39

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