title: installed directory not writable, cannot update packages 'boot', 'class', 'KernSmooth', 'mgcv', 'nnet', 'rpart', 'spatial'
body: <p>I installed the Bioconductor packages on R version 3.1.2 on Ubuntu 14.04 and received the message below:</p>
  
  <blockquote>
    <p>The downloaded source packages are in
      ‘/tmp/RtmpZYw0Qp/downloaded_packages’ Warning message: installed
    directory not writable, cannot update packages 'boot',   'class',
    'KernSmooth', 'mgcv', 'nnet', 'rpart', 'spatial'</p>
  </blockquote>
  
  <p>What does it mean, and how does it affect using the above packages on R?</p>