Portability of the new file(1) command.
@(#) $Header: PORTING,v 1.6 87/11/08 23:03:41 ian Exp $

Read this file only if the program doesn't compile on your system.

I have tried to make a program that doesn't need any command-line
defines (-D) to specify what version of UNIX is in use,
by using the definitions available in the system #include
files. For example, the lstat(2) call is normally found in
4BSD systems, but might be grafted into some other variant
of UNIX. If it's done right (ie., using the same definitions),
my program will compile and work correctly. Look at the #ifdefs
to see how it's done. 

I've also tried to include all the non-portable library routines
I used (getopt, str*).   Non-portable here means `not in every
reasonably standard UNIX out there: V7, System V, 4BSD'.

There is one area that just might cause problems. On System
V, they moved the definition of major() and minor() out of
<sys/types.h> into <sys/sysmacros.h>.  Hence, if major isn't
defined after including types.h, I automatically include sys/sysmacros.h.
This will work for 99% of the systems out there. ONLY if you
have a system in which  neither types.h nor sysmacros.h defines
`major' will this automatic include fail (I hope). On such
systems, you will get a compilation error in trying to compile
a warning message. Please do the following: 

	1) change the appropriate (2nd) #include at the start of 
		fsmagic.c
and	2) let me know the name of the system, the release number,
	   and the name of the header file that *does* include
	   this "standard" definition.

If you are running the old Ritchie PDP-11 C compiler or
some other compiler that doesn't know about `void', you will have
to un-comment-out the definition of `void=int' in the Makefile.

Other than this, there should be no portability problems,
but one never knows these days. Please let me know of any
other problems you find porting to a UNIX system. I don't much
care for non-UNIX systems but will collect widely-used magic 
numbers for them as well as for UNIX systems.

Ian Darwin
Toronto, Canada
