find_library (
          <VAR>
          name | NAMES name1 [name2 ...] [NAMES_PER_DIR]
          [HINTS [path | ENV var]... ]
          [PATHS [path | ENV var]... ]
          [PATH_SUFFIXES suffix1 [suffix2 ...]]
          [DOC "cache documentation string"]
          [NO_CACHE]
          [REQUIRED]
          [NO_DEFAULT_PATH]
          [NO_PACKAGE_ROOT_PATH]
          [NO_CMAKE_PATH]
          [NO_CMAKE_ENVIRONMENT_PATH]
          [NO_SYSTEM_ENVIRONMENT_PATH]
          [NO_CMAKE_SYSTEM_PATH]
          [CMAKE_FIND_ROOT_PATH_BOTH |
           ONLY_CMAKE_FIND_ROOT_PATH |
           NO_CMAKE_FIND_ROOT_PATH]
         )

该命令用于查找库，查找的结果存放在变量VAR，如果没有找到，VAR会被赋值为VAR-NOTFOUND。

如果变量VAR的值非空，那么查找不会进行。

常用选线

REQUIRED 找不到库会报错
HINTS 告诉find_library去哪些路径查找
NO_DEFAULT_PATH 不会在默认路径查找，默认路径见下方，也