[Toybox] awk (Re: ps down, top to go)

[Andy Chu]

Hm one thing I didn't realize is that pdksh and AT&T ksh (ksh93) are
of different lineages.

mksh is a derivative of pdksh, which seems like it hasn't been updated
since 2000 or so.  This is clear from looking at say exec.c in both
trees.  pdksh is ~30K LOC and mksh is ~32K LOC.

http://www.cs.mun.ca/~michael/pdksh/

It also seems like pdksh comes with fewer restrictions than mksh:
http://www.cs.mun.ca/~michael/pdksh/LEGAL .  mksh basically changed
the license to BSD (which I guess you can do for a derivative work if
the original is in the public domain, i.e. no copyright?)

Here is ksh by David Korn, in ast/src/cmd/ksh93, which is ~64K LOC.

https://github.com/att/ast

I just read over a 1994 ksh Usenix article [1], which shows where bash
got a lot of its features.  bash is a big superset of POSIX, and
almost all of the non-POSIX extensions come from ksh.  That appears to
be how bash "won"... by becoming a superset of ksh, which itself was a
superset of POSIX and Bourne shell.

Andy

[1] https://www.usenix.org/legacy/publications/library/proceedings/vhll/full_papers/korn.ksh.a