Give you two files atxt and btxt Append data in btxt to atxt

Give you two files, a.txt and b.txt. Append data in b.txt to a.txt. Input a.txt and b.txt. Output a.txt as a combination of a.txt and b.txt.

Solution

CREATING A FILE AND APPENDING TO IT DATA OF ANOTHER TEXT FILE USING NASM

section .text

   global _start         ;must be declared for using gcc

        

_start:                  ;tell linker entry point

   ;firstly create the file

   mov eax, 8

   mov ebx, file_name

   mov ecx, 0777        ;read, write and execute by all

   int 0x80             ;call kernel

        

   mov [fd_out], eax

   

   ; write into the file

   mov   edx,len          ;number of bytes

   mov   ecx, msg         ;message to write

   mov   ebx, [fd_out]    ;file descriptor

   mov   eax,4            ;system call number (sys_write)

   int   0x80             ;call kernel

        

   ; close the file

   mov eax, 6

   mov ebx, [fd_out]

   

   ; write the message indicating end of file write

   mov eax, 4

   mov ebx, 1

   mov ecx, msg_done

   mov edx, len_done

   int 0x80

   

   ;open the file for reading

   mov eax, 5

   mov ebx, file_name

   mov ecx, 0             ;for read only access

   mov edx, 0777          ;read, write and execute by all

   int 0x80

        

   mov [fd_in], eax

   

   ;read from file

   mov eax, 3

   mov ebx, [fd_in]

   mov ecx, info

   mov edx, 26

   int 0x80

   

   ; close the file

   mov eax, 6

   mov ebx, [fd_in]

   

   ; print the info

   mov eax, 4

   mov ebx, 1

   mov ecx, info

   mov edx, 26

   int 0x80

      

   mov   eax,1             ;system call number (sys_exit)

   int   0x80              ;call kernel

section .data

file_name db ‘a.txt\'

msg db \'Welcome here to Chegg’

len equ $-msg

msg_done db \'Written to file\', 0xa

len_done equ $-msg_done

section .bss

fd_out resb 1

fd_in resb 1

info resb 26