https://cmake.org/cmake/help/latest/command/get_filename_component.html
Get a specific component of a full filename.
get_filename_component(<var><FileName><mode>[CACHE])
Sets <var> to a component of <FileName>, where <mode> is one of:
DIRECTORY = Directory without file name
NAME = File name without directory
EXT = File name longest extension (.b.c from d/a.b.c)
NAME_WE = File name with neither the directory nor the longest extension
LAST_EXT = File name last extension (.c from d/a.b.c)
NAME_WLE = File name with neither the directory nor the last extension
PATH = Legacy alias for DIRECTORY (use for CMake <= 2.8.11)
Paths are returned with forward slashes and have no trailing slashes. If the optional CACHE argument is specified, the result variable is added to the cache.
get_filename_component(<var><FileName><mode>[BASE_DIR<dir>][CACHE])
Sets <var> to the absolute path of <FileName>, where <mode> is one of:
ABSOLUTE = Full path to file
REALPATH = Full path to existing file with symlinks resolved
If the provided <FileName> is a relative path, it is evaluated relative to the given base directory <dir>. If no base directory is provided, the default base directory will be CMAKE_CURRENT_SOURCE_DIR.
Paths are returned with forward slashes and have no trailing slashes. If the optional CACHE argument is specified, the result variable is added to the cache.
get_filename_component(<var><FileName>PROGRAM[PROGRAM_ARGS<arg_var>][CACHE])
The program in <FileName> will be found in the system search path or left as a full path. If PROGRAM_ARGS is present with PROGRAM, then any command-line arguments present in the <FileName> string are split from the program name and stored in <arg_var>. This is used to separate a program name from its arguments in a command line string.
Note
The REALPATH and PROGRAM subcommands had been superseded, respectively, by file(REAL_PATH) and separate_arguments(PROGRAM) commands.
et a specific component of a full filename.
get_filename_component(<var><FileName><mode>[CACHE])
Sets <var> to a component of <FileName>, where <mode> is one of:
DIRECTORY = Directory without file name
NAME = File name without directory
EXT = File name longest extension (.b.c from d/a.b.c)
NAME_WE = File name with neither the directory nor the longest extension
LAST_EXT = File name last extension (.c from d/a.b.c)
NAME_WLE = File name with neither the directory nor the last extension
PATH = Legacy alias for DIRECTORY (use for CMake <= 2.8.11)
Paths are returned with forward slashes and have no trailing slashes. If the optional CACHE argument is specified, the result variable is added to the cache.
get_filename_component(<var><FileName><mode>[BASE_DIR<dir>][CACHE])
Sets <var> to the absolute path of <FileName>, where <mode> is one of:
ABSOLUTE = Full path to file
REALPATH = Full path to existing file with symlinks resolved
If the provided <FileName> is a relative path, it is evaluated relative to the given base directory <dir>. If no base directory is provided, the default base directory will be CMAKE_CURRENT_SOURCE_DIR.
Paths are returned with forward slashes and have no trailing slashes. If the optional CACHE argument is specified, the result variable is added to the cache.
get_filename_component(<var><FileName>PROGRAM[PROGRAM_ARGS<arg_var>][CACHE])
The program in <FileName> will be found in the system search path or left as a full path. If PROGRAM_ARGS is present with PROGRAM, then any command-line arguments present in the <FileName> string are split from the program name and stored in <arg_var>. This is used to separate a program name from its arguments in a command line string.
Note
The REALPATH and PROGRAM subcommands had been superseded, respectively, by file(REAL_PATH) and separate_arguments(PROGRAM) commands.