Hello,I'm REALLY new to this linux stuff.

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Joined: 26 Sep 2006
Posts: 92

2 17 Oct 2006, 06:29

I recently got a dual boot set up between WinXP and Ubuntu 5.10 .
I downloaded the linux FASM and assembled this program!

Code:

format elf executable ;make the weird elf thing that linux uses

mov eax,4     ;call 4 of int 128 for writing
mov ebx,1     ;ebx is 1 for writing to the screen
mov ecx,msg   ;mov msg into ecx
mov edx,size  ;mov the length of the message into edx
int 128       ;interrupt 128(the linux call)

mov eax,1     ;call 1 for exiting program
int 128

msg db 'Hello linux!',10 ;string ending with a newline
size = $-msg ;makes a constant that equals the length of msg

It works as I'd expect,but it's all I can do cause I can't find a complete idiots guide
to using all the system calls. I used ralph browns interrupt list for DOS,but I can't
find the help I need on linux.

What I want to do is write it to a file instead of the screen,but I don't know the
calls for creating and closing files.

So,maybe somebody can help me with an example. That's how I learned what I have in
DOS. Yes,I'm the crazy guy that was also on the DOS forum. Please don't make
a big deal about the fact that I'm using decimal numbers for my interrupts and
stuff. You can write your examples how you want and I'll just figure it out.

but also,if you know a good place where I can get a list of all the calls in great
detail,let me know.

_________________
There are 10 kinds of people in the world.
Those who know binary and those who haven't met me.

17 Oct 2006, 06:29

arafel

Joined: 29 Aug 2006
Posts: 131
Location: Jerusalem, Israel

arafel 17 Oct 2006, 07:54

[warning: shameless plug ahead]

Look at the topmost thread in this subforum.

17 Oct 2006, 07:54

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 17 Oct 2006, 13:20

BTW, is correct to use INT/SYSCALL if you want you program tu run in future versions of the kernel? You can also use INT/SYSCALL on NT based Windowses but you have to call them through the proper API.

17 Oct 2006, 13:20

arafel

Joined: 29 Aug 2006
Posts: 131
Location: Jerusalem, Israel

arafel 17 Oct 2006, 14:06

It's safer to use library calls if you want to be 100% sure, but system calls are relatively safe if you make sure not to use any syscalls that have been scheduled for removal or some major rewrite.

17 Oct 2006, 14:06

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 17 Oct 2006, 14:15

are there some scheduled for removal? if so, be sure to mention it in your docs Smile

17 Oct 2006, 14:15

arafel

Joined: 29 Aug 2006
Posts: 131
Location: Jerusalem, Israel

arafel 17 Oct 2006, 15:04

I spotted about seven syscalls (one of them was some signal related function, don't remember the others) that have comments in the source code along those lines: 'this function superceded by blablabla and maintained only for compatibility'. Not exactly a definite, near future, removal; but I guess not something to be relied upon Smile

I think i have mentioned about all of them in the docs, but will recheck just in case.

17 Oct 2006, 15:04

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 17 Oct 2006, 15:19

thx a lot

17 Oct 2006, 15:19

2

Joined: 26 Sep 2006
Posts: 92

2 18 Oct 2006, 03:39

Quote:

warning: shameless plug ahead

Look at the topmost thread in this subforum.

I did,but I couldn't find the help I needed still. Well,I guess I'll try it
again next time I'm in ubuntu. I'm booted in XP for some really strange stuff.

_________________
There are 10 kinds of people in the world.
Those who know binary and those who haven't met me.

18 Oct 2006, 03:39

Quantum

Joined: 24 Jun 2005
Posts: 122

Quantum 21 Oct 2006, 02:10

A moreless complete reference is here:
http://www.lxhp.in-berlin.de/lhpsyscal.html

Quote:

BTW, is correct to use INT/SYSCALL if you want you program tu run in future versions of the kernel?

It is very safe if you handle the compatibility issues carefully. BTW, you can test for a particular kernel version and OS family (Linux/BSD/...) before performing any syscall. I've seen many bugs in LIBC and other standard libs. You are never safe using LIBC Wink

21 Oct 2006, 02:10

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