a list of posix commands i want to remember, and
the unix release they were introduced (according to
wikipedia):

NAME      DESC                            VERSION
m4	- macro processor		  PWB UNIX
umask	- get/set file creation mask	  System III
xargs	- construct argument lists	  PWB UNIX
ps	- report process status		  v4 AT&T
bc	- arbitrary percision calculator  v6 AT&T
sccs	- version control		  4.3 BSD
uucp	- unix to unix copy		  v7 AT&T
strings	- find strings in a binary file	  2 BSD
csplit	- split files based on context	  PWB UNIX
cal	- print a calendar		  v5 AT&T
diff	- compare two files		  v5 AT&T
ed	- text editor			  PDP-7
expand	- convert tabs to spaces	  3 BSD
id	- report user identity		  System V
ln	- link files			  v1 AT&T
more	- display contents of a file	  3 BSD
pr	- columnate files for printing	  v1 AT&T
tee	- duplicate the standard output	  v5 AT&T
tr	- translate characters		  v4 AT&T
tty	- report users tty		  v1 AT&T