In a software package running both on NetBSD and FreeBSD there are
some subtle differences in Makefiles for the two systems. We need
"MAN" to contain a list of man pages, if "PROG" is not set, while 
FreeBSD needs "MAN4" to be a list of section 4 man pages.

Also man pages describing kernel drivers have to give different 
"SYNOPSIS" lines, so these pages need OS depended preproccessing.

The method I found is this:

---8<---
.if !defined(OSTYPE)
OSTYPE=`uname`
.endif

.if (${OSTYPE} == "NetBSD")
# NetBSD needs MAN to be defined
MAN      =      disdn.4 ipi.4 isdn.4 tel.4 itel.4 ity.4
.endif
--->8---

which doesn't work in NetBSD-current. (Don't know if it ever did.)

It's not easy to see, because this:

---8<---
.if !defined(OSTYPE)
OSTYPE=`uname`
.endif

all:
	@echo "OSTYPE is $(OSTYPE)"
--->8---

will result in:

---8<---
[/tmp] martin@rumolt > make
OSTYPE is NetBSD
--->8---

But if you change @echo to echo you'll see what is wrong:

---8<---
[/tmp] martin@rumolt > make
echo "OSTYPE is `uname`"
OSTYPE is NetBSD
--->8---

A working way is the following:

---8<---

[/tmp] martin@rumolt > cat Makefile
.if !defined(OSTYPE)
OSTYPE=`uname`
.endif

all install foo bar:
        @$(MAKE) -f Makefile.work OSTYPE=$(OSTYPE) $(.TARGET)

[/tmp] martin@rumolt > cat Makefile.work
.if !defined(OSTYPE)
@echo "Don't use this Makefile directly"
.endif

all:
        echo "OSTYPE is $(OSTYPE)"

--->8---

This gives

---8<---
[/tmp] martin@rumolt > make
echo "OSTYPE is NetBSD"
OSTYPE is NetBSD
--->8---

Is there an easier solution? What is the prefered way to do this kind of things?


Martin