pdksh 50e-2ubuntu1 (amd64 binary) in ubuntu vivid

 The Public Domain Korn Shell "pdksh" is a mostly complete AT&T ksh
 look-alike, but has been superseded by mksh. This transitional dummy
 package exists to fulfil the needs of existing users, dependencies
 and build-dependencies by providing pdksh symlinks to the legacy
 flavour of mksh. You can safely remove it once you have no remaining
 users or scripts depending on pdksh any more (do make sure to check
 users' login shells).
 .
 Note: the mksh legacy flavour is not intended for interactive use.
 Please change your login shell to /bin/mksh and copy /etc/skel/.mkshrc
 to your home directory.