title: Installing the R-package "rgeos" on linux: geos-config not found or not executable
body: <p>I am running R 3.4.1 on gentoo.
  When i try to install the 'rgeos' package, i get this:</p>
  
  <pre><code>&gt; install.packages("rgeos")
  Installing package into ‘/home/jody/R/x86_64-pc-linux-gnu-library/3.4’
  (as ‘lib’ is unspecified)
  trying URL 'https://stat.ethz.ch/CRAN/src/contrib/rgeos_0.4-2.tar.gz'
  Content type 'application/x-gzip' length 255244 bytes (249 KB)
  ==================================================
  downloaded 249 KB
  
  * installing *source* package ‘rgeos’ ...
  ** package ‘rgeos’ successfully unpacked and MD5 sums checked
  configure: CC: x86_64-pc-linux-gnu-gcc
  configure: CXX: x86_64-pc-linux-gnu-g++
  configure: rgeos: 0.4-2
  checking for /usr/bin/svnversion... yes
  configure: svn revision: 581
  checking for geos-config... no
  no
  configure: error: geos-config not found or not executable.
  ERROR: configuration failed for package ‘rgeos’
  * removing ‘/home/jody/R/x86_64-pc-linux-gnu-library/3.4/rgeos’
  
  The downloaded source packages are in
      ‘/tmp/RtmppEeDps/downloaded_packages’
  Warning message:
  In install.packages("rgeos") :
    installation of package ‘rgeos’ had non-zero exit status
  </code></pre>
  
  <p><strong>(The same happens if i try to install rgeos on gentoo with R 3.5.1, and also on Centos 7.5 with R 3.5.1.)</strong></p>
  
  <p>While there is a <code>rgeos/configure</code> which is executable in the tar file mentioned above, there is indeed no <code>geos-config</code> in there.</p>
  
  <p>How can i get the <code>rgeos</code> package installed?</p>
  
  <p>Is there perhaps a binary version which i could download?</p>