A 'Hello World' program in GAS for linux x86_64

main.s

.global _start

.section .data
    message: .ascii "Hello, World!\n"
    len = . - message

.section .text
_start:
    movq $1, %rax           # sys_write
    movq $1, %rdi           # stdout
    movq $message, %rsi     # message
    movq $len, %rdx         # len of message
    syscall                 # sys_write

    movq $60, %rax          # sys_exit
    movq $0, %rdi           # exit code 0
    syscall                 # sys_exit

run.sh

mkdir -p build/
mkdir -p build/part

as -c -o build/part/main.s.o main.s
ld -o  build/a.out build/part/main.s.o

./build/a.out