PD-ksh is a mostly complete AT&T ksh look-alike (see NOTES file for a list
of things not supported).  Work is mostly finished to make it fully
compatible with both POSIX and AT&T ksh (when the two don't conflict).

Since pdksh is free and compiles and runs on most common unix systems, it
is very useful in creating a consistent user interface across multiple
machines.  For example, in the CS dept. of MUN, pdksh is installed on a
variety of machines including Suns, HPs, DecStations, pcs running Linux,
etc., and is the login shell of ~5200 users.