Command Line arguments in NASM assembly on 64-bit Linux

args.asm

; print all command line arguments (5 characters) and exit
; for 64-bit systems, Linux syscalls
; for simplicity, this program does not calculate the length of the strings.
; assemble with: nasm -f elf64 -o args args.asm
; link with: ld -o args args.o

sys_write	equ	1		; the linux WRITE syscall
sys_exit	equ	60		; the linux EXIT syscall
sys_stdout	equ	1		; the file descriptor for standard output (to print/write to)

length		equ	5		; the length of the string we wish to print (fixed string length of the arguments)

section .data
	linebreak	db	0x0A	; ASCII character 10, a line break

section .text
global _start
_start:
	pop	r8			; pop the number of arguments from the stack
	pop	rsi			; discard the program name, since we only want the commandline arguments

top:
					; loop condition
	cmp	r8,	0		; check if we have to print more arguments
	jz	exit			; if not, jump to the 'end' label

					; print the argument
	mov	rax,	sys_write	; set the rax register to the syscall number we want to execute (WRITE)
	mov	rdi,	sys_stdout	; specify the file we want to write to (standard output in this case)
	pop	rsi			; pop a pointer to the string we want to print from the stack
	mov	rdx,	length		; specify the (fixed) length of the string we want to print
	syscall				; execute the system call

					; print a newline
	mov	rax,	sys_write	; rax is overwritten by the kernel with the syscall return code, so we set it again
	mov	rdi,	sys_stdout
	mov	rsi,	linebreak	; this time we want to print a line break
	mov	rdx,	1		; which is one byte long
	syscall
	
	dec	r8			; count down every time we print an argument until there are none left
	jmp	top			; jump back to the top of the loop

					; the program is finished, now exit cleanly by calling the EXIT syscall
exit:
	mov	rax,	sys_exit	; load the EXIT syscall number into rax
	mov	rdi,	0		; the program return code
	syscall				; execute the system call

If I recall correctly, this was only meant to get one-character integer arguments, and was done as a learning excersise for myself. Aka not meant to be used in production.

i respect that, I'm doing some exercise too and i found your gist in top of google search, in fact my code is your code with some improvisation