title: Unable to install ‘sf’ R package on Ubuntu 16.04 LTS
body: <p>I'm not able to install <code>sf</code> <code>R</code> package on <code>Ubuntu 16.04 LTS</code>. I tried</p>
  
  <pre><code>install.packages("sf")
  </code></pre>
  
  <p>as well as</p>
  
  <pre><code>devtools::install_github("r-spatial/sf")
  </code></pre>
  
  <p>after running</p>
  
  <pre><code>sudo add-apt-repository ppa:ubuntugis/ubuntugis-unstable
  sudo apt-get update
  sudo apt-get install libudunits2-dev libgdal-dev libgeos-dev libproj-dev 
  </code></pre>
  
  <p>Getting the following error message:</p>
  
  <blockquote>
    <p>configure: error: gdal-config not found or not executable.</p>
    
    <p>ERROR: configuration failed for package ‘sf’</p>
  </blockquote>
  
  <p>Wonder what is the way to install <code>sf</code>?</p>