What is the linker complaining about?

Question

linux

I'm trying to build a program in C (without pluses) using the GMP library:

gcc -g -L/usr/lib/x86_64-linux-gnu/ -llibgmp main.c

I get an error:
/usr/bin/ld: cannot find -llibgmp
I don’t understand why this is so, because the library clearly exists and the linker knows about it:

$ readlink /usr/lib/x86_64-linux-gnu/libgmp.so
libgmp.so.10.3.0
$ ldconfig -p | grep libgmp
  libgmpxx.so.4 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libgmpxx.so.4
  libgmpxx.so (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libgmpxx.so
  libgmp.so.10 (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libgmp.so.10
  libgmp.so (libc6,x86-64) => /usr/lib/x86_64-linux-gnu/libgmp.so
$ gcc --version
gcc (Ubuntu 5.4.0-6ubuntu1~16.04.4) 5.4.0 20160609

Answer 1

In general, apparently something was crooked in Ubuntu. The problem is solved by downloading the original library from gmplib.org.

Answer 2

You told the linker to look for the liblibgmp.so library :) Out of the blue? The linker is smart, it knows that library names start with "lib..." and therefore automatically appends that to the key value. And of course you don’t have the liblibgmp.so file :)