CSC161 2010F, Class 03: Linux Files and Permissions

Overview:
* Review.
* Lab!

Admin:
* For tomorrow, read Chapter 1 of K&R.  
  Note: It goes fast and you won't understand everything.  That's okay.
* For Friday, read Chapter 1 of Raymond.  
  Note: Once again, you won't understand everything.  
  So bring questions and comments.)
* Are there questions on Assignment 1?
  * "Explain the mnemonic chmod question."
    [Ten minutes later ...] chmod a-r foo
  * "Can you help with the rm -f problem?"
    No
    * "Can I do ..."
      STOP!  Don't give it away.
      And "No"
  * I can't remember what question it is and I've never been told
    that there are no dumb questions, but ... what does "the manual"
    mean?
    * "The manual" = "The stuff you get when you type man"

What were the broad concepts you learned?
* UM
* Unix provides a naive version of security
* No command is simple, most have lots and lots of options
* You can navigate with the terminal (why use a GUI?)
* Text based interface is "too legit to quit"
  * Translation: "A timeless way of interacting with the computer."
  * Re-translation: "There are obvious reasons to use a textual UI."
* There's a reason that we have GUI's - They can make things more obvious,
  particularly for former engineers who are now chefs.

But there's more to learn!  So do the lab.

---

Pipes
* What does a pipe do anyway?
  * It sends the output of one program to another program
* Why "pipe"?
  * The designers of Unix liked plumbing metaphors
* Then why does in point in the wrong direction?
  * Um ... because '-' had another meaning?

Less
* Why is less called less?

Cut
* Preserves only the columns you ask it to preserve (cuts out everything
  else)

What should I do when I give you too much lab?
* This time ... give you until tomorrow