CS208 Introduction to Computer Systems
Monday, 8 May 2023

+ Questions left over from the bombs

+ Coming up
- You're going to write a simple command shell
- Example command shells: bash, zsh

+ Processes in Unix: try these things

    $ ps aux
    $ ps auxww
        what does ps do? what are all the columns in the output?

    $ ls -l
        what is all that stuff?
        in particular, what is the -rw-r--r-- stuff on the left?

    $ ls > something.txt
    $ cat something.txt
    $ wc something.txt
    $ wc < something.txt
    $ cat something.txt | wc
    $ echo "hi there" | wc
        what does wc do?
        what does > do?
        what does < do?
        what does | do?

    $ top
        Ctrl-Z puts top to sleep
    $ jobs -l
        Shows "stopped jobs"
    $ fg
        Wakes up some stopped job

- What is a process?
- Signals
- Interprocess communication

+ Command shell (bash, zsh, etc)
- >
- <
- |
- &

+ Sample programs
- ...

+ Functions to get to know
- fork
- exec
- signal
- pipe
- dup2