NASM code with user output, and then input into an argument. (code error)

I have had problems implementing user output into and argument with my below code.

An example of BASH showing, a similar example function of what i would like to implement in NASM.

read -p "Enter the group you would like to create: " newgroup
groupadd $newgroup

The reason why I am creating this code is to show a comparison of different languages, used within Linux, This is one part of my research project. So i know, this can be done in other languages e.g. Python BASH and C etc. Before anyone asks.

I believe I’m somewhere on the right lines, here is the code below.

;---------------------------NSAM----------------------
section .data                  ; initialized data, can be var's
userg:      db "Type in the user group to add:  ",10,0  ; 1st string, 10 is used to drop down a line. 0 is used to end the line.
userg_L:    equ $-userg ; string length, automatically updates how long the string is, so you don't have to type 10 etc. every time its changed 
respns:     db "groupadded: ",10,0          ; 2nd string, 10 is used to drop down a line. 0 is used to end the line.
respns_L    equ $-respns ; 2nd string length, automatically updates how long the string is, so you don't have to type 10 etc. every time its changed 
command:         db      '/bin/groupadd', 0h    ; command to execute.
arg1:            db      userg, 0h ; Shows all users on the system.
argu:            dd      command
                 dd      arg1               ; arguments passed to the command line.
                 dd      0h                 ; struct.
enviro:          dd      0h                 ; no arguments are need for the environment variables.

;========================================================
section .bss                           ; uninitialised data, also can be var's
userg_V resb    255            ; reserves 255 bytes of data.

;========================================================

section .text               ; Asm core code. any of the sections can be in any order.
global _start:          ; Makes _start the global function

_start:                 ; Makes _start the global function
mov     eax, 0x04       ; store the system call code = 4 e.g. = kernel function (sys_write)
mov     ebx, 0x01       ; 1 is the code to where to write the Asm out to. 1= The terminal
mov     ecx, userg      ; contains the label of the string.
mov     edx, userg_L    ; this is the length of the string.
int     80h             ; calls the Linux kernel

mov     eax, 0x03       ; 3 is the code to read user input. e.g. kernel function (sys_read)
mov     ebx, 0x00       ; This is the error code memory block.
mov     ecx, userg_V        ; reserves 255 bytes of data name of string.
mov     edx, 255        ; reserves 255 bytes of data.
int     80h             ; calls the Linux kernel.

mov     eax, 0x04       ; store the system call code = 4 e.g. = kernel function (sys_write)
mov     ebx, 0x01       ; 1 is the code to where to write the Asm out to. 1= The terminal
mov     ecx, respns     ; calls the var
mov     edx, respns_L       ; calls the userg var length 
int     80h         ; calls the Linux kernel.

mov     eax, 0x04       ; store the system call code = 4 e.g. = kernel function (sys_write)
mov     ebx, 0x01       ; 1 is the code to where to write the Asm out to. 1= The terminal
mov     ecx, userg_V        ; reserves 255 bytes of data name of string.
mov     edx, 255        ; reserves 255 bytes of data.
int     80h         ; calls the Linux kernel.

mov     edx, enviro         ; Environment variables
    mov     ecx, argu           ; Arguments to pass to the command line
    mov     ebx, command        ; address to execute
    mov     eax, 11             ; SYS_EXECVE kernel opcode (11)
    int     80h
call    exit            ; Calls the exit function.


;---------------------------------ASM exit code below!-------------------------------------------
exit:
mov     eax, 0x01       ; [EAX] is 1 this is the exit code! e.g. = kernel function (sys_exit)
mov     ebx, 0x00       ; This is the error code memory block.
int     80h         ; calls the Linux kernel.

The error is:

ld -s -o myasm myasm.o
myasm.o: In function `arg1':
myasm.asm:(.data+0x3e): relocation truncated to fit: R_386_8 against `.data'

This error was fixed using dd but It will not add the user group to the system.

The below code works to show all users but will not take user input as the argument. This is an example of working command code but without user input. So how would one implement user input, with the command line code.

command:         db      '/bin/cat', 0h    ; command to execute.
arg1:            db      '/etc/passwd', 0h ; Shows all users on the system.

Answer

Here is a fixed version. Note that groupadd might not be in /bin, and you should probably print an error message if exec fails.

;---------------------------NASM----------------------
section .data                  ; initialized data, can be var's
userg:      db "Type in the user group to add:  ",10  ; 1st string, 10 is used to drop down a line.
userg_L:    equ $-userg ; string length, automatically updates how long the string is, so you don't have to type 10 etc. every time its changed
respns:     db "groupadded: ",10          ; 2nd string, 10 is used to drop down a line. 0 is used to end the line.
respns_L    equ $-respns ; 2nd string length, automatically updates how long the string is, so you don't have to type 10 etc. every time its changed
command:         db      '/bin/groupadd', 0h    ; command to execute.
argu:            dd      command
                 dd      userg_V               ; arguments passed to the command line.
                 dd      0h                 ; struct.
enviro:          dd      0h                 ; no arguments are need for the environment variables.

;========================================================
section .bss                           ; uninitialised data, also can be var's
userg_V resb    255            ; reserves 255 bytes of data.

;========================================================

section .text               ; Asm core code. any of the sections can be in any order.
global _start:          ; Makes _start the global function

_start:                 ; Makes _start the global function
mov     eax, 0x04       ; store the system call code = 4 e.g. = kernel function (sys_write)
mov     ebx, 0x01       ; 1 is the code to where to write the Asm out to. 1= The terminal
mov     ecx, userg      ; contains the label of the string.
mov     edx, userg_L    ; this is the length of the string.
int     80h             ; calls the Linux kernel

mov     eax, 0x03       ; 3 is the code to read user input. e.g. kernel function (sys_read)
mov     ebx, 0x00       ; This is the error code memory block.
mov     ecx, userg_V        ; reserves 255 bytes of data name of string.
mov     edx, 255        ; reserves 255 bytes of data.
int     80h             ; calls the Linux kernel.
push    eax             ; save length of input

mov     eax, 0x04       ; store the system call code = 4 e.g. = kernel function (sys_write)
mov     ebx, 0x01       ; 1 is the code to where to write the Asm out to. 1= The terminal
mov     ecx, respns     ; calls the var
mov     edx, respns_L       ; calls the userg var length
int     80h         ; calls the Linux kernel.

mov     eax, 0x04       ; store the system call code = 4 e.g. = kernel function (sys_write)
mov     ebx, 0x01       ; 1 is the code to where to write the Asm out to. 1= The terminal
mov     ecx, userg_V    ; the input text
mov     edx, [esp]      ; the length of the input text
int     80h         ; calls the Linux kernel.

pop     eax             ; get back input length
mov     [eax + userg_V - 1], byte 0 ; chop off trailing newline
mov     edx, enviro         ; Environment variables
    mov     ecx, argu           ; Arguments to pass to the command line
    mov     ebx, command        ; address to execute
    mov     eax, 11             ; SYS_EXECVE kernel opcode (11)
    int     80h

;---------------------------------ASM exit code below!-------------------------------------------
exit:
mov     eax, 0x01       ; [EAX] is 1 this is the exit code! e.g. = kernel function (sys_exit)
mov     ebx, 0x00       ; This is the error code memory block.
int     80h         ; calls the Linux kernel.