$ nasm -f elf hello.asm $ ld -o hello hello.o ld: i386 architecture of input file `hello.o' is incompatible with i386:x86-64 output $ nasm -f elf64 hello.asm

$ nasm -f elf hello.asm $ ld -o hello hello.o ld: i386 architecture of input file `hello.o' is incompatible with i386:x86-64 output $ nasm -f elf64 hello.asm $ ld -o hello hello.o $ ./hello hello, friend