cc -o test test.c
cc -o test2 test2.c
as sd.s
ld -o sd.o -r a.out -lc -la
cc -c sd?.c
lked Z sd.o sd1.o -lc -la
mv a.out sd1
lked Z sd.o sd2.o -lc -la
mv a.out sd2
rm *.o
