在C ++项目中使用共享库的问题

Question

I am trying to change MongoDB's source and use functions from an external library. I have been able to change the build scripts ( SCons files) and force the compiler to do extra linking with the libraries I am going to use. Although I am not facing any issues while compiling the source code and linking the object files, I face an odd error when starting mongod . Here is the message that I am receiving (immediately before the mongod process terminates):

./mongod: error while loading shared libraries: .1: cannot open shared object file: No such file or directory

I was able to fix this by moving the .so file of the library to /lib/x86_64-linux-gnu and rename it to .1, which is the path mongod expects to find the shared library. I don't know what is the cause of this problem, but everything is fine with other libraries such as pthread . Is there any specific solution for this problem? In other words, what should I do to make the executable program look for the library file in other locations using proper naming (not .1)?

Here is the output while LD_DEBUG=all mongod:

  4564: 
  4564: file=libpthread.so.0 [0];  needed by ./mongod [0]
  4564: find library=libpthread.so.0 [0]; searching
  4564:  search cache=/etc/ld.so.cache
  4564:   trying file=/lib/x86_64-linux-gnu/libpthread.so.0
  4564: 
  4564: file=libpthread.so.0 [0];  generating link map
  4564:   dynamic: 0x00007f6ddccb7d50  base: 0x00007f6ddcaa0000   size: 0x000000000021c448
  4564:     entry: 0x00007f6ddcaa6cf0  phdr: 0x00007f6ddcaa0040  phnum:                  9
  4564: 
  4564: 
  4564: file=.1 [0];  needed by ./mongod [0]
  4564: find library=.1 [0]; searching
  4564:  search cache=/etc/ld.so.cache
  4564:   trying file=/lib/x86_64-linux-gnu/.1
  4564:  search path=/lib/x86_64-linux-gnu/tls/x86_64:/lib/x86_64-linux-gnu/tls:/lib/x86_64-linux-gnu/x86_64:/lib/x86_64-linux-gnu:/usr/lib/x86_64-linux-gnu/tls/x86_64:/usr/lib/x86_64-linux-gnu/tls:/usr/lib/x86_64-linux-gnu/x86_64:/usr/lib/x86_64-linux-gnu:/lib/tls/x86_64:/lib/tls:/lib/x86_64:/lib:/usr/lib/tls/x86_64:/usr/lib/tls:/usr/lib/x86_64:/usr/lib        (system search path)
  4564:   trying file=/lib/x86_64-linux-gnu/tls/x86_64/.1
  4564:   trying file=/lib/x86_64-linux-gnu/tls/.1
  4564:   trying file=/lib/x86_64-linux-gnu/x86_64/.1
  4564:   trying file=/lib/x86_64-linux-gnu/.1
  4564:   trying file=/usr/lib/x86_64-linux-gnu/tls/x86_64/.1
  4564:   trying file=/usr/lib/x86_64-linux-gnu/tls/.1
  4564:   trying file=/usr/lib/x86_64-linux-gnu/x86_64/.1
  4564:   trying file=/usr/lib/x86_64-linux-gnu/.1
  4564:   trying file=/lib/tls/x86_64/.1
  4564:   trying file=/lib/tls/.1
  4564:   trying file=/lib/x86_64/.1
  4564:   trying file=/lib/.1
  4564:   trying file=/usr/lib/tls/x86_64/.1
  4564:   trying file=/usr/lib/tls/.1
  4564:   trying file=/usr/lib/x86_64/.1
  4564:   trying file=/usr/lib/.1
  4564: 
  ./mongod: error while loading shared libraries: .1: cannot open shared object file: No such file or directory

Answer 1

I somehow found the solution for my problem. Thought it might be also helpful to others.

Basically, when you are using make to create shared libraries, you should define the .so file name. This was my case and I just set it to a proper value and everything is now working, at least I have fixed this error by doing so.

Looking it up in Google, I found that -soname option of gcc is designed to do so.