title: Update R base - Ubuntu from 3.4.4 to 3.5.2 - Azure
body: <p>I'm using Ubuntu 16.04 on Azure Linux Virtual Machine</p>
  
  <pre><code>lsb_release -a
  No LSB modules are available.
  Distributor ID: Ubuntu
  Description:    Ubuntu 16.04.5 LTS
  Release:        16.04
  Codename:       xenial
  </code></pre>
  
  <p>The current R version for Rstudio/Rserver is 3.4.4 and I would like to update it to the latest version (i.e. version 3.5.2)</p>
  
  <pre><code>R --version
  R version 3.4.4 (2018-03-15) -- "Someone to Lean On"
  Copyright (C) 2018 The R Foundation for Statistical Computing
  Platform: x86_64-pc-linux-gnu (64-bit)
  </code></pre>
  
  <p>From some reasons, the most common method doesn't work:</p>
  
  <pre><code>apt-get update
  apt-get upgrade
  </code></pre>
  
  <p>So I did some research and find this <a href="https://www.biostars.org/p/88651/" rel="nofollow noreferrer">post</a> on biostars.org</p>
  
  <p>One of the posts says the following codes might work</p>
  
  <pre><code>sudo su 
  echo "deb https://cloud.r-project.org/bin/linux/ubuntu xenial-cran35/" &gt;&gt; /etc/apt/sources.list 
  apt-key adv --keyserver keyserver.ubuntu.com --recv-keys E084DAB9 
  apt-get update 
  apt-get install r-base 
  apt-get install r-base-dev
  </code></pre>
  
  <p>However, after <code>apt-get install r-base</code> I'm getting the following error message:</p>
  
  <pre><code>root@VMforR:/usr/local/bin# apt-get install r-base
  Reading package lists... Done
  Building dependency tree
  Reading state information... Done
  Some packages could not be installed. This may mean that you have
  requested an impossible situation or if you are using the unstable
  distribution that some required packages have not yet been created
  or been moved out of Incoming.
  The following information may help to resolve the situation:
  
  The following packages have unmet dependencies:
   r-base : Depends: r-recommended (= 3.5.2-1xenial) but it is not going to be installed
  E: Unable to correct problems, you have held broken packages.
  </code></pre>
  
  <p>I don't understand what "held broken packages" means, and more importantly, how to update the R base?</p>