Hello World assembly macOS x86_64

32.asm

; nasm -f macho 32.asm
; ld -macosx_version_min 10.12 -o 32 32.o -lSystem
; ./32
global _main 

section .text
_main:
	push dword msg.len
	push dword msg
	push dword 1
	mov eax, 4
	sub esp, 4
	int 0x80
	add esp, 16

	push dword 0
	mov eax, 1
	sub esp,12
	int 0x80

section .data

msg: db "Hello world!", 10
.len: equ $-msg

64.asm

; NASM Intel Syntax for NASM assembly "Hello World!"
;  nasm -f macho64 64.asm
;  ld -macosx_version_min 10.12 -o 64 64.o -lSystem
;./64
section .data
	msg: db 'Hello World', 0xA
	.len equ $-msg

section .text

global _main

_main: 
	mov eax, 0x2000004
	mov ebx, 1
	mov rsi, msg
	mov rdx, msg.len
	syscall

	mov eax, 0x2000001
	mov ebx, 0
	syscall

64gas.asm

// AT&T Syntax for GAS Assembly 'Hello World!'

# as -arch x86_64  -o 64gas.o 64gas.asm
# ld -macosx_version_min 10.12 -o 64gas 64gas.o -lSystem
# ./64gas

.data

    HelloWorldString:
    .ascii "Hello World!\n"

.text

.globl _main

_main:
    # load all the arguments for write()
    movl $0x2000004, %eax
    movl $1, %ebx
    movq HelloWorldString@GOTPCREL(%rip), %rsi
    movq $100, %rdx
    # raises software interrupt to call write()
    syscall

    # call exit()
    movl $0x2000001, %eax
    movl $0, %ebx
    syscall