NASM, read a file and print the content - linux

Question

I have this piece of code in NASM (for linux) that supposed to open an existing file, read it and print the content on the screen, but does not work, can someone tell me what am I doing wrong?(hello.txt is the name of the file)
section .data
file db "./hello.txt", 0
len equ 1024
section .bss
buffer: resb 1024
section .text
global _start
_start:
mov ebx, [file] ; name of the file
mov eax, 5
mov ecx, 0
int 80h
mov eax, 3
mov ebx, eax
mov ecx, buffer
mov edx, len
int 80h
mov eax, 4
mov ebx, 1
mov ecx, buffer
mov edx, len
int 80h
mov eax, 6
int 80h
mov eax, 1
mov ebx, 0
int 80h

Answer 1

mov ebx, [file] ; name of the file
mov eax, 5
mov ecx, 0
int 80h
Is wrong. Loose the square brackets around file. You are passing the file name instead of a pointer to the filename.
mov ebx, file ; const char *filename
mov eax, 5
mov ecx, 0
int 80h

Answer 2

I see here a lot of mistakes, in order:
mov ebx, [file] ; name of the file
mov eax, 5
mov ecx, 0
int 80h
Here, as said, u must lose square brackets (because the function needs a pointer, not a value)
mov eax, 3
mov ebx, eax
mov ecx, buffer
mov edx, len
int 80h
Here, u must save the file descriptor from eax, before writing there value 3, else u just loose it
mov eax, 4
mov ebx, 1
mov ecx, buffer
mov edx, len
int 80h
Well. Here u using ebx register, so better way is to save file descriptor in memory. And for display, you take 1024 bytes from buffer, which is not correct. After reading from the file, the eax register will contain the number of characters read, so after reading from the file it will be better to store the value from the eax register in edx
mov eax, 6
int 80h
Again. U close the file, but ebx contains dirt, although it must contain a file descriptor
Correct code must look like this:
section .data
file db "text.txt",0 ;filename ends with '\0' byte
section .bss
descriptor resb 4 ;memory for storing descriptor
buffer resb 1024
len equ 1024
section .start
global _start
_start:
mov eax,5 ;open
mov ebx,file ;filename
mov ecx,0 ;read only
int 80h ;open filename for read only
mov [descriptor],eax ;storing the descriptor
mov eax,3 ;read from file
mov ebx,[descriptor] ;your file descriptor
mov ecx,buffer ;read to buffer
mov edx,len ;read len bytes
int 80h ;read len bytes to buffer from file
mov edx,eax ;storing count of readed bytes to edx
mov eax,4 ;write to file
mov ebx,1 ;terminal
mov ecx,buffer ;from buffer
int 80h ;write to terminal all readed bytes from buffer
mov eax,6 ;close file
mov ebx,[descriptor] ;your file descriptor
int 80h ;close your file
mov eax,1
mov ebx,0
int 80h
This is not a perfect code, but it should work