Heh, I wouldn't be surprised if people have slept with a copy of K&R under their pillows lol.
For historical interest,
a tutorial from Kernighan --> You would be surprised how much of it still holds water in 2008.
UNIX and derived systems on the other hand has changed quite a lot over the years.
Code:
#define NPROC 50 /* max number of processes */
From param.h, UNIX v6. kernel source code.
Things like if you get a pascal or fortran or C++ compiler along with a C Compiler. The standard libraries and function calls defined by POSIX and such today, whether sigaction() is available or not. lp or lpr, does vi exist yet, the name of the kernel file (/unix, /bsd, /boot/kernel/kernel, blah blah), package management (if any), support for mmap(), classic, home brew, or GNU C compiler, Thompson, Bourne, or Korn shells, /proc or no /proc, a couple of headers, paths, Berkly sockets, TCP/IP support, monolithic kernels (with and without modules) or microkernels,
e.t.c.
The strange, sad, and freaking funny thing? Have you ever looked in /usr/share/doc/{smm,usd,psd} ?
FreeBSD has the 4.3BSD 'Revised June 8, 1993' line printer spooler manual from the old System Managers Manual -- my OpenBSD system says 'Revised May 31, 2002' on its copy --- BSD printing has changed so little since then that it is probably the best resource on it I've seen.
When I wanted to figure out how to setup NFS and found the syntax from Linux didn't work, I just hit the old SMM and read, somethings don't change a lot.
Other things, really do change a lot!