title: Versions of GLIBC
body: <p>I have created c++ application in Ubuntu machine. I have copied binary to Centos machine. Got error:</p>
  
  <pre><code>/usr/lib/libstdc++.so.6: version `GLIBCXX_3.4.21' not found
  </code></pre>
  
  <p>I decided to check which versions of glibc I have in my machines with help of ldd --version command:</p>
  
  <pre><code>Ubuntu: 2.23
  Centos6.9: 2.12
  </code></pre>
  
  <p>Why CentOS cmplains regarding GLIBCXX_3.4.21, while Ubuntu owns glibc version 2.23?</p>