~ - Home Directory
. - Current Directory
.. - Enclosing Directory

$ cd ~/Dropbox/code
$ cd ..
$ pwd
/Users/rd/Dropbox

$ ls
$ ls -la
$ la
$ ls -tla

$ mkdir projects
$ mkdir -v code
$ mkdir -p code/sinatra-app/public code/sinatra-app/views

$ ls --help
ls: illegal option -- -
usage: ls [-ABCFGHLOPRSTUWabcdefghiklmnopqrstuwx1] [file ...]
$ man --help
$ man ls

$ mv projects old-projects
$ cp app.rb old-projects/
$ cp -R old-projects really-old-projects

$ rm junk.txt
$ rm -rf really-old-projects

$ echo
$ grep
$ la | grep .txt
$ tar
$ cat
$ head
$ tail
$ brew
$ tree
$ which
$ whoami
$ curl
$ nano
$ say 'Hello'

Add #!/usr/bin/env ruby to top of the file.

$ chmod +x food_trucks.rb
$ ./food_trucks.rb

• /usr/local/bin should be first!: export PATH=/usr/local/bin:$PATH
• Always append to the end of the $PATH
• Postres.app: export PATH=$PATH:/Applications/Postgres.app/Contents/Versions/9.3/bin

$ printenv
$ echo $PATH
$ brew doctor
$ nano ~/.zshrc
$ nano ~/.bashrc

$ which ruby
$ chruby
   ruby-1.9.3-p545
   ruby-2.0.0-p451
   ruby-2.0.0-p594
   ruby-2.1.2
   ruby-2.1.3
 * ruby-2.1.4
   ruby-2.1.5
$ chruby ruby-2.1.5
$ echo "ruby-2.1.5" > ~/.ruby-version

$ ln -s "/Applications/Sublime Text 2.app/Contents/SharedSupport/bin/subl" /usr/bin/subl
$ which atom
/usr/local/bin/atom
$ la /usr/local/bin/atom

$ cd ~/Dropbox/code/launchvotes
$ atom .
$ subl .

$ ps aux | grep safari
$ kill 123

$ tar -zxvf plans_to_take_over_the_wolrd.tar.gz
$ tar -xvjf area51_research_documents.tar.gz2

$ tar -tf filename.tar.gz

slooooooow

$ grep -rn collection_select ~/Dropbox/code

faster

$ brew install ack
$ ack collection_select ~/Dropbox/code

way fast

$ brew install the_silver_searcher
$ ag collection_select ~/Dropbox/code

$ find ~ -name "time.rb"

say 'Thank you'