Text #
Text is a series of bytes.
- For English keyboard chars, each byte is one character.
- So the text “Hi, Welcome to CS 2010” is 22 bytes.
Structure of a Computer #
- CPU
- RAM
- Disk
- I/O: Keyboard, screen, network
Where do we store data? #
- Running program: in RAM
- Longer than one program? On disk, in a file.
- A file is a series of bytes, with a name (short text)
Demonstrate file <-> bytes and different UI modes #
- Use gedit to create sample file
- Use nemo to show properties:
- Name
- Size in bytes
Two user interface modes:
- GUI, like gedit/nemo
- gives a single clear view
- common actions are visual and discoverable
- Less common actions are hidden or entirely missing
- Show space free in nemo
- System monitor
- CLI, repeat with echo/ls/stat/vim/duf/free -h
- “we can do better than point and grunt: language”
- communicate with text: commands and command output
- Need to know the language(s), both concepts and grammar
hd (FILE)man ascii- Absolutely need to read some docs.
- Option 3: Natural language
- opencode - Qwen
- “Create a text file named ‘hello.txt’ containing the lyrics of Twinkle Twinkle Little Star”
- What are the ascii codes for the characters in the file?
- Append a snowman emoji to the end of the file.
- Still need to know the concepts, although but there’s some improved discoverability through discussion.
File System Structure #
- We need to store files
- That’s a sequence of bytes
- And some metadata: Name, maybe file type, dates, etc.
- Early computers just said your files go on a disk
- Doesn’t work with too many files
- We get this file cabinet metaphor, almost.
- One document is a “file”, they go in “folders”, folders live on “disks”.
- Technical detail: paths
- Every file or directory has a path
- One string of characters
- On Linux/Mac, starts with “/”
- On Windows, starts with a drive letter (probably C: for local)
- Sequence of parts separated by / or \.
- If we’re finding a file, the last part is the file name.
- The rest of the parts are directory names.
- Every file or directory has a path
- Relative paths:
- Every running program (including file managers and terminal windows) has a working directory.
- Explain ./ and ../
