CODEWITHSUNDEEP
linuxg++glfw
Vinny Horgan
Vinny Horgan

Reputation: 11

Where does g++ look for libraries to link?

So I'm currently using Lubuntu 18.4 32bit and was trying to get the GLFW library up and going. I noticed that when you compile a program using GLFW you need to link many libraries and was wondering where exactly does g++ look in the filesystem when you type g++ main.cpp -lglfw?

Upvotes: 1

Views: 2837

Answers (1)

Vlad Havriuk
Vlad Havriuk

Reputation: 1451

For compiler:

echo | g++ -x c++ -E -Wp,-v - >/dev/null
  • echo | prints empty "source code" and closes stdin
  • -x c++ to specify the language (with this option it prints more detailed info)
  • -E says g++ to stop after preprocessing stage
  • - at the end means read code from stdin
  • -Wp,-v to pass -v directly to preprocessor
  • >/dev/null to redirect extra output to /dev/null (void)

Example output:

ignoring nonexistent directory "/usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../x86_64-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../include/c++/10.2.0
 /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../include/c++/10.2.0/x86_64-pc-linux-gnu
 /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/../../../../include/c++/10.2.0/backward
 /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include
 /usr/local/include
 /usr/lib/gcc/x86_64-pc-linux-gnu/10.2.0/include-fixed
 /usr/include
End of search list.

For linker:

ld --verbose | grep SEARCH_DIR | tr -s ' ;' \\012
  • --verbose tells ld to print settings info
  • | grep SEARCH_DIR select lib directory info
  • | tr -s ' ;' \\012 makes output pretty (replace ; with new line)

Example output:

SEARCH_DIR("/usr/x86_64-pc-linux-gnu/lib64")
SEARCH_DIR("/usr/lib")
SEARCH_DIR("/usr/local/lib")
SEARCH_DIR("/usr/x86_64-pc-linux-gnu/lib")

So the GLFW library should be in one of those directories.

Source: https://transang.me/library-path-in-gcc/

Upvotes: 4

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