usr/bin/ld: cannot find -l<nameOfTheLibrary>

Question

I'm trying to compile my program and it returns this error :

usr/bin/ld: cannot find -l<nameOfTheLibrary> 

in my makefile I use the command g++ and link to my library which is a symbolic link to my library located on an other directory.

Is there an option to add to make it work please?

Answer 1

To figure out what the linker is looking for, run it in verbose mode.

For example, I encountered this issue while trying to compile MySQL with ZLIB support. I was receiving an error like this during compilation:

/usr/bin/ld: cannot find -lzlib 

I did some Googl'ing and kept coming across different issues of the same kind where people would say to make sure the .so file actually exists and if it doesn't, then create a symlink to the versioned file, for example, zlib.so.1.2.8. But, when I checked, zlib.so DID exist. So, I thought, surely that couldn't be the problem.

I came across another post on the Internets that suggested to run make with LD_DEBUG=all:

LD_DEBUG=all make 

Although I got a TON of debugging output, it wasn't actually helpful. It added more confusion than anything else. So, I was about to give up.

Then, I had an epiphany. I thought to actually check the help text for the ld command:

ld --help 

From that, I figured out how to run ld in verbose mode (imagine that):

ld -lzlib --verbose 

This is the output I got:

================================================== attempt to open /usr/x86_64-linux-gnu/lib64/libzlib.so failed attempt to open /usr/x86_64-linux-gnu/lib64/libzlib.a failed attempt to open /usr/local/lib64/libzlib.so failed attempt to open /usr/local/lib64/libzlib.a failed attempt to open /lib64/libzlib.so failed attempt to open /lib64/libzlib.a failed attempt to open /usr/lib64/libzlib.so failed attempt to open /usr/lib64/libzlib.a failed attempt to open /usr/x86_64-linux-gnu/lib/libzlib.so failed attempt to open /usr/x86_64-linux-gnu/lib/libzlib.a failed attempt to open /usr/local/lib/libzlib.so failed attempt to open /usr/local/lib/libzlib.a failed attempt to open /lib/libzlib.so failed attempt to open /lib/libzlib.a failed attempt to open /usr/lib/libzlib.so failed attempt to open /usr/lib/libzlib.a failed /usr/bin/ld.bfd.real: cannot find -lzlib 

Ding, ding, ding...

So, to finally fix it so I could compile MySQL with my own version of ZLIB (rather than the bundled version):

sudo ln -s /usr/lib/libz.so.1.2.8 /usr/lib/libzlib.so 

Voila!

Answer 2

If your library name is say libxyz.so and it is located on path say:

/home/user/myDir 

then to link it to your program:

g++ -L/home/user/myDir -lxyz myprog.cpp -o myprog