users.pl

#!/usr/bin/perl

use Config::Augeas;

use warnings;
use strict;

my $aug_root = '/home/rpinson/bas/augeas';
my $aug = Config::Augeas->new(root => $aug_root);

$aug->set('/augeas/load/Simplelines/incl[last()+1]', '/users');
$aug->load();

# Define a variable called $nomatches which points to /files/users only if user "shanw" is not present
$aug->defvar(nomatches => '/files/users[count(*[.="shanw"])=0]');
# This won't do anything if $nomatches doesn't point to the file
$aug->set('$nomatches/01', 'shanw');
$aug->save();