teaching machines

CS 330 Lecture 2 – Shell Scripting

January 27, 2016 by . Filed under cs330, lectures, spring 2016.

Agenda

TODO

Note

Today we’re going to write shell scripts together to accomplish some tasks that have come up often enough in my own computing that I think you might benefit as well. I’m trying to find a happy ground between me doing a lot of coding in front of you and me pushing problems at you without discussion. The approach we’ll take today is we’ll write the code together on the whiteboard, each of you contributing a line or comment.

As we write these, we can start to think about the shell as a language. Questions that might arise include:

  1. How does the shell manage abstraction of data? Is data typed?
  2. How does the shell manage abstraction? Can I hide a complex operation under a narrow interface?
  3. How can data be passed around between abstractions?
  4. How are errors handled?

Code

foozip

/usr/lib/ruby/2.7.0/rubygems/dependency.rb:311:in `to_specs': Could not find 'coderay' (>= 0) among 56 total gem(s) (Gem::MissingSpecError)
Checked in 'GEM_PATH=/.gem/ruby/2.7.0:/var/lib/gems/2.7.0:/usr/lib/ruby/gems/2.7.0:/usr/share/rubygems-integration/2.7.0:/usr/share/rubygems-integration/all:/usr/lib/x86_64-linux-gnu/rubygems-integration/2.7.0:/home/johnch/.gems', execute `gem env` for more information
	from /usr/lib/ruby/2.7.0/rubygems/dependency.rb:323:in `to_spec'
	from /usr/lib/ruby/2.7.0/rubygems/core_ext/kernel_gem.rb:62:in `gem'
	from ./coderay:24:in `
'

crun

/usr/lib/ruby/2.7.0/rubygems/dependency.rb:311:in `to_specs': Could not find 'coderay' (>= 0) among 56 total gem(s) (Gem::MissingSpecError)
Checked in 'GEM_PATH=/.gem/ruby/2.7.0:/var/lib/gems/2.7.0:/usr/lib/ruby/gems/2.7.0:/usr/share/rubygems-integration/2.7.0:/usr/share/rubygems-integration/all:/usr/lib/x86_64-linux-gnu/rubygems-integration/2.7.0:/home/johnch/.gems', execute `gem env` for more information
	from /usr/lib/ruby/2.7.0/rubygems/dependency.rb:323:in `to_spec'
	from /usr/lib/ruby/2.7.0/rubygems/core_ext/kernel_gem.rb:62:in `gem'
	from ./coderay:24:in `
'

book

/usr/lib/ruby/2.7.0/rubygems/dependency.rb:311:in `to_specs': Could not find 'coderay' (>= 0) among 56 total gem(s) (Gem::MissingSpecError)
Checked in 'GEM_PATH=/.gem/ruby/2.7.0:/var/lib/gems/2.7.0:/usr/lib/ruby/gems/2.7.0:/usr/share/rubygems-integration/2.7.0:/usr/share/rubygems-integration/all:/usr/lib/x86_64-linux-gnu/rubygems-integration/2.7.0:/home/johnch/.gems', execute `gem env` for more information
	from /usr/lib/ruby/2.7.0/rubygems/dependency.rb:323:in `to_spec'
	from /usr/lib/ruby/2.7.0/rubygems/core_ext/kernel_gem.rb:62:in `gem'
	from ./coderay:24:in `
'