(2017)
I would expect a modern tutorial to focus on x86-64 (syscall/sysenter) instead of the old int 0x80 conventions for 32-bit x86. int 0x80 syscalls still work in 64-bit mode, but use a 32-bit calling convention, which might be confusing - see also https://stackoverflow.com/questions/46087730/what-happens-if....
If you want to build a really minimal ELF file (on Linux), this is perhaps the possible minimum: https://www.muppetlabs.com/~breadbox/software/tiny/teensy.ht...
