title: undefined reference to symbol 'pthread_key_delete@@GLIBC_2.2.5
body: <p>I'm trying to make a file in Ubuntu and when i make i keep getting this error:</p>
  
  <pre><code>/usr/bin/ld: ../../gtest-1.7.0/libgtest.a(gtest-all.cc.o): undefined reference to symbol     'pthread_key_delete@@GLIBC_2.2.5'
  /lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line
  collect2: error: ld returned 1 exit status
  make[2]: *** [src/tests/run_tests] Error 1
  make[1]: *** [src/tests/CMakeFiles/run_tests.dir/all] Error 2
  make: *** [all] Error 2
  </code></pre>
  
  <p>I saw someone mentioning to go into Makefile and adding '-L /lib64 -l pthread' to the variable LDFLAGS but how do you do that? Totally new to linux here =X</p>