CS208 Introduction to Computer Systems
Monday, 20 Feb 2023


    ls | wc
    ls -l | wc -l
    ls > out.txt
    ls -l > out2.txt
    cat file.txt | grep moose
    cat file.txt | cat | cat | grep moose

+ Want help?
- Source code, not screenshots
- Relevant line numbers
- Brief replication instructions:
    - what is the bad thing?
    - how to make the bad thing happen?

+ Next assignment
- Posted tomorrow
- Due next Monday
- Buffer overflow attacks
- Wednesday class: function-calling in asm,
    stack maintenance, etc.

+ Questions

+ Zombies
- malloc/free, open/close, connect/disconnect...
- fork/wait

+ Multi-processing causes trouble
- command_a | command_b
    what's going on here?
- the scheduler
    there's a hardware clock (vibrating crystal)
    that ticks periodically and tells the CPU to run
    the scheduler -- "preemptive multi-processing"

    some function calls invoke the scheduler indirectly
    read, write, wait,...
- guarantees (and the lack thereof)
- samples: race.c, 
- Benefits worth it?