Re: output of a command

[Martin Knappe]

> Ultimately, make is just a tool for invoking commands -- specifically
> shell commands.  So just break each of those steps down into a shell
> script or shell fragment that does what you want.  Remember that if you
> want to do more than one thing in a shell fragment, you need to specify
> it as one line to make using continuation-\ since otherwise make invokes
> each command in a new shell process.  And secondly remember that if you
> want to reference a $var in the shell fragment you need to use $$ so
> that it's not interpreted as a make variable.
>
> Something like this (untested):
>
> .SUFFIXES: .asm .o .bin
> .PHONY: all
>
> all: binarydisk.bin
>
> %.bin: %.asm
>         $(AS) $< -o $@
>
> foo1.bin: foo1.asm
>
> foo2.bin: foo2.asm foo1.bin
>         $(AS) -DFOO=`stat -c %s $(word 2,$^)` $< -o $@
>         # or:
>         # env FOO=`stat -c %s $(word 2,$^)` $(AS) $< -o $@
>
> sectorsize := 512
>
> binarydisk.bin: foo1.bin foo2.bin
>         len=`stat -c %s $(word 1,$^)`; \
>         start=`expr $$len / $(sectorsize)`; \
>         if [ `expr $$len % $(sectorsize)` != 0 ]; then \
>           start=`expr $$start + 1`; \
>         fi; \
>         dd if=$(word 1,$^) of=$@ bs=$(sectorsize) && \
>         dd if=$(word 2,$^) of=$@ bs=$(sectorsize) seek=$$start
>
> Brian
>   

I tried with your hints but it still doesnt work...I was trying to 
follow your example (leaving out all the cryptic stuff), this is how far 
I've got:

SECTOR_SIZE=512

all:
   make bootdisk.bin
bootdisk.bin: 512.bin
   -rm bootdisk.bin
   touch bootdisk.bin
   dd if=512.bin of=bootdisk.bin count=1 seek=0
   dd if=gdt.bin of=bootdisk.bin count=1 seek=1 #"actually", count 
should be (GDT_SIZE)/(SECTOR_SIZE), GDT_SIZE is guaranteed to be a 
multiple of 512
512.bin: 512.asm gdt.bin
   -rm 512.bin
   nasm -f bin 512.asm -o 512.bin -DGDT_SIZE=`stat -c %s gdt.bin` 
-DSECTOR_SIZE=512 #env variables GDT_SIZE and SECTOR_SIZE are both 
referenced from within 512.asm
gdt.bin: gdt.asm
   -rm gdt.bin
   nasm -f bin gdt.asm -o gdt.bin

This doesnt work (and you can probably see why). Can you please make the 
necessary corrections (as few as possible) and make it not too cryptic, 
so I can understand what is going on...or, if necessary, explain it a 
little bit...I've tried the make manual, really, but I get confused :-(