I logged into my kali and ran a few commands.
nokogiri -v
Nokogiri (1.6.7.1)
---
warnings: []
nokogiri: 1.6.7.1
ruby:
version: 2.2.4
platform: x86_64-linux-gnu
description: ruby 2.2.4p230 (2015-12-16) [x86_64-linux-gnu]
engine: ruby
libxml:
binding: extension
source: system
compiled: 2.9.3
loaded: 2.9.3
root@kali:~# hostname
kali
root@kali:~# **dpkg -l |grep nokogiri**
ii ruby-nokogiri 1.6.7.1-1 amd64 HTML, XML, SAX, and Reader parser for Ruby
root@kali:~# **cewl -v**
CeWL 5.3 (Heading Upwards) Robin Wood (robin@digi.ninja) (https://digi.ninja/)
Missing URL argument (try --help)
root@kali:~#
I see those tools installed already course I am using the precann'ed vbox download for kali.
So why are you trying to install it?