Get a specific component of a full filename.

get_filename_component(<VAR> <FileName> <COMP> [CACHE])

Set <VAR> to a component of <FileName>, where <COMP> 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 without directory or longest extension
ABSOLUTE  = Full path to file
REALPATH  = Full path to existing file with symlinks resolved
PATH      = Legacy alias for DIRECTORY (use for CMake <= 2.8.11)

Paths are returned with forward slashes and have no trailing slahes. The longest file extension is always considered. 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>]

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.