CS456 - Systems Programming Spring 2026

Displaying ./code/nasm/forkexec/fork.asm.old

; Fork
; Compile with: nasm -f elf fork.asm
; Link with (64 bit systems require elf_i386 option): ld -m elf_i386 fork.o -o fork
; or since we have a makefile, just type "make fork"
; Run with: ./fork
 
%include        '../functions.asm' ; remember to provide the path to the file
 
SECTION .data
childMsg        db      'This is the child process', 0h     ; a message string
parentMsg       db      'This is the parent process', 0h    ; a message string
 
SECTION .text
global  _start
 
_start:
 
    mov     eax, 2              ; invoke SYS_FORK (kernel opcode 2)
    int     80h
 
    cmp     eax, 0              ; if eax is zero we are in the child process
    jz      child               ; jump if eax is zero to child label
 
parent:
    mov     eax, parentMsg      ; inside our parent process move parentMsg into eax
    call    sprintLF            ; call our string printing with linefeed function
 
    call    quit                ; quit the parent process
 
child:
    mov     eax, childMsg       ; inside our child process move childMsg into eax
    call    sprintLF            ; call our string printing with linefeed function
 
    call    quit                ; quit the child process