title: Possibly undefined macro: AC_PROG_LIBTOOL
body: <p>I want to build protobuf, so I just cloned the package and <code>cd</code> in the directory.
  When I type <code>./autogen.sh</code>, some error happened.</p>
  <p><img src="https://i.stack.imgur.com/mcByI.jpg" alt="screenshot of the error when I type ./autogen.sh" /></p>
  <p>I receive callback:</p>
  <pre><code>configure.ac:104: error: possibly undefined macro: AC_PROG_LIBTOOL
        If this token and others are legitimate, please use m4_pattern_allow.
        See the Autoconf documentation.
  autoreconf: /home/zhangxl/my/autoconf/bin/autoconf failed with exit status: 1
  </code></pre>
  <p>Someone said I should install libtool, but I have already installed autoconf, automaker, libtool and m4, but all of them are built from source, because I can't access the sudo password.</p>
  <p><img src="https://i.stack.imgur.com/JnWhh.jpg" alt="screenshot showing the cmd errors." /></p>
  <p>This is my .bashrc file:</p>
  <pre><code>export PATH=$PATH:/home/zhangxl/my/libtool/bin
  export CPLUS_INCLUDE_PATH=/hpme/zhangxl/my/libtool/include:$CPLUS_INCLUDE_PATH
  export LIBRARY_PATH=/home/zhangxl/my/libtool/lib:$LIBRARY_PATH
  export LD_LIBRARY_PATH=/home/zhangxl/my/libtool/lib:$LD_LIBRARY_PATH
  </code></pre>
  <p>I think maybe the .bashrc file is not correct.</p>