.lcomm buf 20
.text
.global _start
_start:

    movl $buf, %eax
    movl $20, %ebx

copyAgain:
    movb $' ',(%eax)
    addl $1,%eax
    subl $1,%ebx
    jnz  copyAgain

    movl $1,%eax
    movl $0,%ebx
    int $0x80