when installing on linux virtual machine oracle 12c I can not advance by:
The pdksh package is not available, but some other package makes reference to the. This may mean that the package is missing, obsolete or only available from some other source
N: Omitting the "extra.list.backup" file from the "/etc/apt/sources.list.d/" directory, as it has an invalid file name extension E: The libpthread-stubs0 package could not be located E: The lsb-cxx package could not be located E: The «pdksh» package does not have a candidate for installation help !!!