var ErrNotFound = exec.ErrNotFound
ErrNotFound is the error resulting if a path search failed to find an executable file.
Look searches for an executable named file, using getenv to look up environment variables. If getenv is nil, os.Getenv will be used. If file contains a slash, it is tried directly and getenv will not be called. The result may be an absolute path or a path relative to the current directory.