CS208 Introduction to Computer Systems
Wednesday, 25 February 2026

+ The videos
- Older versions of sample code
- Class vs. videos

+ Recap
- what's a process?
    - a running program
    - has a "PID"
    - a user name that the process is "running as"
        (e.g., "ls is running as jondich")
    - parent
    - a running status: running, runnable, terminated,
        asleep waiting for I/O or something else,...
    - has a file descriptor table
    - has a stack and heap and other memory contents
    - ...[you could look at the linux source code]...
- fork() -- forktest.c
- execlp() -- exectest.c
    - CAREFUL: code after exec doesn't get executed
- perror, errno, and sys_errlist[]???

+ Other variants of exec
- exec_test_with_args.c

+ Files
- file descriptor table
- operations: open, read, write, seek, close
- various levels of file I/O support in C
    fopen vs. open, fwrite vs. write, etc.

+ dup2
- redirect.c
- try writing the sequence of steps for "wc -l < filename"

+ pipe