PD-ksh is a software program that closely resembles AT&T ksh (Korn shell). It offers near-complete compatibility with the original version.
PDksh is currently being maintained by Michael Rendell, who took over from Simon J. Gerraty at the later suggestion. The software has been undergo significant work to make it fully compatible with both POSIX and AT&T ksh, when the two don't conflict. There is also a short list of things that have been added since the last public pdksh release (4.9), including auto-configuration, arrays, $(( .. )), [[ .. ]], variable attributes, co-processes, extended file globbing, many POSIXisms, and many bug fixes.
It is important to note that pdksh is provided AS IS, with NO WARRANTY, either expressed or implied. Although the bulk of the code in pdksh is in the public domain, some files are copyrighted (but freely distributable) and subject to certain conditions (eg, don't remove copyright, document any changes, etc.).
The following is a list of machines that pdksh is reported to work on: -/PC Linux 1.x,2.x, -/PC NetBSD 0.9a, -/PC BSDI 1.1, -/PC FreeBSD 2.x, 3.x, -/PC OpenBSD, -/PC Interactive/Sunsoft 3.0.1 and 4.1 (note that problems have been reported with isc3.2 - see the BUG-REPORTS file), -/PC OS/2, Commadore/Amiga NetBSD 1.0, Dec/alpha OSF/1 v2.x, v3.x, Dec/alpha NetBSD 1.1B, Dec/pmax Ultrix 4.2, Dec/vax Ultrix 2.2 (not tested recently :-)), Dec/vax 4.3BSD+NFS (MtXinu) (not tested recently :-)), HP/pa HP-UX 9.01, IBM/RS/6000 AIX 3.2.5, MIPS/m120 RISC/os 5.0 (bsd43 environ), NeXT NeXTStep 3.2, SGI/IRIX 6.2, Sun/sun4 SunOS 4.1.3, 4.1.4, Sun/sun4 Solaris 2.x, Sun/sun386i SunOS 4.0.2, Sun/sun3 SunOS 4.0.3, 4.1.1_U1, and Stardent/TitanOS 4.2.
In summary, if you are looking for a reliable and highly recommended AT&T ksh look-alike that is free and works perfectly on most common UNIX systems, then PD-ksh is an excellent software to explore.
Version 5.2.14: N/A