ld: library not found for -lnetcdf - cmake

Question

I am new to CMake. I can not resolve the flowing error. Could someone help me?
------------ERROR--------------
ld: library not found for -lnetcdf
collect2: error: ld returned 1 exit status
make[3]: *** [NUP] Error 1
make[2]: *** [CMakeFiles/NUP.dir/all] Error 2
make[1]: *** [CMakeFiles/NUP.dir/rule] Error 2
make: *** [NUP] Error 2
------------------- CMake File------------------
cmake_minimum_required(VERSION 3.10.0)
project(NUP Fortran)
enable_language(Fortran)
set(INCLUDE_FILE /usr/local/Cellar/netcdf/4.7.4/include)
set(lib_FILE /usr/local/Cellar/netcdf/4.7.4/lib)
find_package(netcdf REQUIRED)
if(netcdf_FOUND)
include_directories(${INCLUDE_FILE})
set(
SOURCE_FILES
${PROJECT_BINARY_DIR} unpack.f90
)
add_executable(NUP ${SOURCE_FILES} )
target_link_libraries(NUP netcdf)
endif()
--------------unpack.f90-------------------
PROGRAM unpack_array
IMPLICIT NONE
INCLUDE 'netcdf.inc'
INTEGER, PARAMETER :: dp = SELECTED_REAL_KIND(12,307)
......
I am using MACOS Catalina. Apple clang version 11.0.3 (clang-1103.0.32.59)
Target: x86_64-apple-darwin19.4.0

Answer 1

If you're using find_package() to find NetCDF on your machine, you shouldn't need to manually specify the paths as you have. Let find_package do that for you.
Note: CMake doesn't ship with a Find Module for NetCDF, so you'll have to download one (like this one) from the internet. Then, you need to tell CMake where to locate this FindNetCDF.cmake file on your system using CMAKE_MODULE_PATH. Finally, you can use the NetCDF::NetCDF imported target to link NetCDF to your project's targets.
cmake_minimum_required(VERSION 3.10.0)
project(NUP Fortran)
# Don't need this, you already enabled Fortran above in the 'project' call.
enable_language(Fortran)
set(INCLUDE_FILE /usr/local/Cellar/netcdf/4.7.4/include)
set(lib_FILE /usr/local/Cellar/netcdf/4.7.4/lib)
# Add the location of the 'FindNetCDF.cmake' file to your module path.
list(APPEND CMAKE_MODULE_PATH "/path/to/downloaded/find/module")
# Then, call find package for NetCDF.
find_package(NetCDF REQUIRED)
if(${NetCDF_FOUND})
# Don't need this if you use the imported target below.
include_directories(${INCLUDE_FILE})
# Don't provide directories with source file list.
set(SOURCE_FILES
${PROJECT_BINARY_DIR}
unpack.f90
)
add_executable(NUP ${SOURCE_FILES})
# Use the imported target to link netcdf instead.
target_link_libraries(NUP PRIVATE NetCDF::NetCDF)
endif()
As commented, there are other approaches to adding NetCDF to your CMake project. If you use a different find module, the syntax of the provided NetCDF CMake variables and imported targets may be slightly different. You'll have to examine the find module file itself.
In addition, you may instead use a CMake package configuration file (e.g. netCDFConfig.cmake) downloaded from the internet to add NetCDF to your project. In this case, you would still use find_package(), but you would specify the configuration file's location using CMAKE_PREFIX_PATH, rather than CMAKE_MODULE_PATH.
You can find detailed descriptions for each of these approaches in the CMake find_package() documentation. I highly encourage you spend some time to read it.