a shecode example build on ubuntu 32bit.

write a sample shellcode, build it.

$ nasm -f elf helloworld.asm
$ ld helloworld.o

runshellcode.c will read a shekkcode.bin to a buffer, and run code from the buffer.

$ gcc runshellcode.c -o runshellcode

build your shellcode

$ cc -m32   -c -o shellcode.o shellcode.S
$ objcopy -S -O binary -j .text shellcode.o shellcode.bin

enjoy: $ ./runshellcode shellcode.bin

get more example from: http://shell-storm.org/shellcode/files/shellcode-811.php