usr/bin/ld: cannot find -l

Question

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

usr/bin/ld: cannot find -l

in my makefile I use the c

Answer 1

Compile Time

When g++ says cannot find -l, it means that g++ looked for the file lib{nameOfTheLibrary}.so, but it couldn't find it in the shared library search path, which by default points to /usr/lib and /usr/local/lib and somewhere else maybe.

To resolve this problem, you should either provide the library file (lib{nameOfTheLibrary}.so) in those search paths or use -L command option. -L{path} tells the g++ (actually ld) to find library files in path {path} in addition to default paths.

Example: Assuming you have a library at /home/taylor/libswift.so, and you want to link your app to this library. In this case you should supply the g++ with the following options:

g++ main.cpp -o main -L/home/taylor -lswift

• Note 1: -l option gets the library name without lib and .so at its beginning and end.

• Note 2: In some cases, the library file name is followed by its version, for instance libswift.so.1.2. In these cases, g++ also cannot find the library file. A simple workaround to fix this is creating a symbolic link to libswift.so.1.2 called libswift.so.

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Runtime

When you link your app to a shared library, it's required that library stays available whenever you run the app. In runtime your app (actually dynamic linker) looks for its libraries in LD_LIBRARY_PATH. It's an environment variable which stores a list of paths.

Example: In case of our libswift.so example, dynamic linker cannot find libswift.so in LD_LIBRARY_PATH (which points to default search paths). To fix the problem you should append that variable with the path libswift.so is in.

export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/home/taylor