Tag Archives: Linux

linux

Programming with FASM – the format ELF executable – part 006 .

Let’s read from a text file named new_file.txt with an assembler program.

Assembly (x86)
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[mythcat@desk fasm]$ vim read_file.fasm
[mythcat@desk fasm]$ ./fasm.x64 read_file.fasm
flat assembler  version 1.73.16  (16384 kilobytes memory, x64)
2 passes, 261 bytes.
[mythcat@desk fasm]$ ./read_file
FASM : Hello, world![mythcat@desk fasm]$

The source code is easy to understand. This source code shows you how you can use a macro for print. The base of this source code use INT 0x80 with a rax register for many functions like open, read and close. I… Read More »

Programming with FASM – the format ELF executable – part 005 .

Let’s write into a text file named new_file.txt with an assembler program. First, you need to create this text file using the command touch.

Assembly (x86)
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[mythcat@desk fasm]$ vim write_file.fasm
[mythcat@desk fasm]$ ./fasm.x64 write_file.fasm
flat assembler  version 1.73.16  (16384 kilobytes memory, x64)
2 passes, 256 bytes.
[mythcat@desk fasm]$ touch new_file.txt
[mythcat@desk fasm]$ cat new_file.txt
[mythcat@desk fasm]$ ./write_file
[mythcat@desk fasm]$ cat new_file.txt
FASM : Hello, world!

The assembler FASM let us to write in the file using the INT 80 and some functions used with rax, rbx, rcx, rdx registers. For example the seek function of… Read More »

Programming with FASM – the format ELF executable – part 004 .

The tutorial for today is a simple one. I will show you how to delete the file created with in the last tutorial. Let’s create a new file named delete_file.fasm and used to delete the new_file.txt.

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[mythcat@desk ~]$ cd fasm/
[mythcat@desk fasm]$ vim delete_file.fasm
[mythcat@desk fasm]$ ./fasm.x64 delete_file.fasm
flat assembler  version 1.73.16  (16384 kilobytes memory, x64)
2 passes, 170 bytes.
[mythcat@desk fasm]$ ls new_file.txt
new_file.txt
[mythcat@desk fasm]$ ./delete_file
[mythcat@desk fasm]$ ls new_file.txt
ls: cannot access 'new_file.txt': No such file or directory
[mythcat@desk fasm]$

In the file delete_file.fasm I used the int 0x80 and mov rax, 10. The kernel is accessed using… Read More »