I am currently trying to install doxygen on my computer, but upon running doxygen through the command line it fails with this error:

doxygen: error while loading shared libraries: libclang.so.6: cannot open shared object file: No such file or directory

I have tried multiple ways of installing it. I tried using apt-get, I tried building it from source, and I tried the unique solution suggested in this StackExchange answer. When I try to build it from source, cmake fails with this error:

 ~/Documents/Repos/doxygen/build/CMakeFiles$ cmake -G "Unix Makefiles" ..
CMake Error at /usr/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:148 (message):
  Could NOT find FLEX (missing: FLEX_EXECUTABLE)
Call Stack (most recent call first):
  /usr/share/cmake-3.5/Modules/FindPackageHandleStandardArgs.cmake:388 (_FPHSA_FAILURE_MESSAGE)
  /usr/share/cmake-3.5/Modules/FindFLEX.cmake:230 (FIND_PACKAGE_HANDLE_STANDARD_ARGS)
  CMakeLists.txt:84 (find_package)

-- Configuring incomplete, errors occurred!

I have even tried installing clang manually, but all to no avail.

  • When running doxygen you get the message about libclang.so.6 and you also say that you used the suggestion in stackoverflow.com/questions/49220422/… installin clang-6.0. What happens if you give the command ldd <path_to_doxygen_executable>/doxygen in respect to clang? Is the directory where clang 6.0 is installed in your LD_LIBRARY_PATH? – albert May 8 '18 at 13:54
  • 1
    Regarding the building from sources, it looks like flex is not installed or it is installed in a place cmake cannot find it. – albert May 8 '18 at 14:03
  • doxygen should install using apt and run fine on 16.04, pulling in libclang1-3.6 and libllvm3.6v5 as dependencies if necessary. If you followed the linked instructions literally (which are for 17.10) then possibly you have messed up the versions of clang/llvm on your system? – steeldriver May 8 '18 at 14:12
  • Libclang is version 3.6 and libllvm is 3.6v5. I tried installing flex using apt-get and the build still fails with the same error. – Ian MathWiz May 9 '18 at 3:21
  • Upon running ldd it says libclang.so.6 => not found even after I tried reinstalling libclang 6 and doxygen using apt-get. – Ian MathWiz May 9 '18 at 7:04

After upgrading to Ubuntu 18.04, installing flex and bison with apt, and rebuilding from source using these instructions, I was finally able to get doxygen to work.

  • Good to see that you succeeded although you needed to install a new version of the OS and did the build yourself instead of using a provided Ubuntu package (but this would probably not be the newest version, but the 1.8.13 version). – albert May 10 '18 at 14:08

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