Lesson 1: The Very Basics¶

Today’s Agenda¶

• Getting (to) Linux

• The Terminal & Shell

  • Scripts, file paths, special characters

• Productivity tricks

  • Getting help

• IRC

  • Vocabulary
  • Get connected
  • Etiquette
  • #wwucs, #wwu-devops, #wwu-alumni

A note about notation¶

• Variables

  • $varname
  • <varname>

• Shell prompt

  • $
  • `literal stuff in backticks`

• foo, bar, baz, username, etc.

How to get (to) Linux¶

• How many have it already installed?

• Install VM or dual-boot

• When stuck on Windows, use PuTTy:

• Students:

  ssh <username>@linux.cs.wwu.edu
  

Trying Linux on a Virtual Machine¶

Virtual machines act as a full system on a physical machine

• Hypervisors:

  • VirtualBox (free)
  • VMWare (mostly free)
  • KVM (Linux only hosts)
  • Parallels

• Public Cloud Virtual Machines

  • Amazon EC2, Rackspace Cloud, Google Compute Engine, etc

• Easy way to test without breaking your machine!

Installing Linux on Virtualbox¶

1. Download and install: https://www.virtualbox.org/wiki/Downloads

2. Grab the latest minimal ISO: http://cdimage.debian.org/debian-cd/current/amd64/iso-cd/

3. Create VM

   1. New -> Name “Debian” -> Default Ram -> Default Disk settings
   2. Settings -> Storage -> Empty -> CD/DVD Drive -> Select ISO
   3. Start -> press enter -> Skip media check

4. \o/

Vagrant & VirtualBox¶

• Vagrant is a tool used with Virtualbox (and other) platforms
• Make a reproducible pre-installed Linux environment
• Download and install: http://www.vagrantup.com/
• Clone our repo, start and access the vm:

# clone
git clone https://github.com/WWUDevOps/WWUDevOpsVagrant

# start up
cd WWUDevOpsVagrant
vagrant up

# access vm
vagrant ssh

Vagrant cheat sheet¶

# start
vagrant up

# stop
vagrant halt

# destroy (remove vm)
vagrant destroy

# ssh to the vm
vagrant ssh

Also check out the Vagrant Documentation for more information.

The Terminal¶

• Used to mean the keyboard+monitor

  • Now that’s a crash cart

• Terminal emulator

• Shell: Use bash; others include csh, zsh, tsch

  • ~/.bashrc

Basic Shell Commands¶

• ls, cd, cat, echo
• invoke/call an installed program
• get help: man <program>

test@x230 ~ $ tree
.
├── Documents
│   ├── Code
│   │   └── scripts
│   │       └── test.sh
│   ├── School
│   └── Work
└── Pictures
    ├── manatee.gif
    └── turtle.png

6 directories, 5 files

Invoking a script¶

$ ls -l
$ chmod +x $filename

Arguments are extra information that you pass to a script or program when you call it. They tell it in more detail what you want to do.

$ ls -a -l
$ ls -al

Why pass arguments on the command line rather than having an interactive mode?

File Paths¶

• . means current directory
• .. means parent directory
• Tilde (~) means your homedir (/home/$username)
• / separates directories (not \)
• / is root directory, so ~ expands to /home/$username/
• current path appears in your prompt: I’m logged in as the user test on the machine named x230

test@x230 ~ $ ls
Documents  Pictures
test@x230 ~ $ cd Documents/
test@x230 ~/Documents $ ls
Code  School  Work
test@x230 ~/Documents $

Special Characters¶

• escape with \ to use them literally
• # means a comment
• ; allows multiple commands per line
• !, ?, *, &&, &
• Regular expressions (we’ll learn more later)

Type less¶

• Reverse-i-search

  • ctrl+r then type command

• aliases

  • ~/.bashrc

• Tab completion

Automation > Typing > Mouse

Help, get me out of here!¶

• ctrl+c kills/quits

• ctrl+d sends EOF (end-of-file)

  • also means logout

• :q gets you out of Vi derivatives and man pages

  • esc - esc - :q if you changed modes

• read what’s on your screen; it’ll help you

Knowledge Check¶

test@x230 ~ $ tree
.
├── Documents
│   ├── Code
│   │   └── scripts
│   │       └── test.sh
│   ├── School
│   └── Work
└── Pictures
    ├── manatee.gif
    └── turtle.png
6 directories, 5 files

• What user am I logged in as?
• What command did I just run?
• What is my current directory when I run that command?

More about Man Pages¶

• the manual (rtfm):

  $ man <program>
  $ man man
  

• use /phrase to search for phrase in the document; n for next match

• else:

  $ <program> --help
  

Documentation¶

Man pages, blogs you find by Googling, StackOverflow

• Contribute to community

  • Correct it if it’s wrong
  • Remind them what newbies don’t know
  • Write your own

• For your future self as well

• Start now

Asking for help¶

It’s okay to ask.

1. What should be happening?
2. What’s actually happening?
3. Google it
4. Skim the manuals of each component
5. Identify a friend, mentor, or IRC channel who could help
6. When they’re not busy, give them a quick synopsis of points 1 and 2, mentioning what possibilities you’ve ruled out by searching.

Contributions = expertise + time

Don’t waste experts’ time, but do build your expertise.

IRC¶

• Internet Relay Chat
• Very old (RFC 1459 May 1993)
• Works on everything (no GUI needed)
• The people you want to listen to are there

A Client¶

Use irssi in screen

# This step is optional, but persistent IRC is cool
$ ssh <username>@<preferred shell host>

# start Screen
$ screen -S irc

# start your client
$ irssi

# after ending ssh session, to get back:
$ ssh <username>@<preferred shell host>
$ screen -dr IRC

Networks¶

/connect irc.freenode.net

/nick <myawesomenickname>
/msg nickserv register <password> <email>

/nick <myawesomenickname>
/msg nickserv identify <password>

Channels¶

/join #osu-lug
/join #devopsbootcamp

Commands¶

• take action with /me does thing`
• everything else starting with / is a command

/say $thing
/join, /part, /whois <nick>, /msg, /help <command>

Note that nothing shows up in the channel when you run a /whois command; it shows up either in your status buffer or your conversation with the person.

12:04 -!- _test_ [~test@c-50-137-46-63.hsd1.or.comcast.net]
12:04 -!-  ircname  : Example User
12:04 -!-  channels : #ExampleChannel
12:04 -!-  server   : moorcock.freenode.net [TX, USA]
12:04 -!-  hostname : c-50-137-46-63.hsd1.or.comcast.net 50.137.46.63
12:04 -!-  idle     : 0 days 0 hours 2 mins 38 secs [signon: Wed Nov  6
12:00:30
                      2013]
12:04 -!- End of WHOIS

Useful tricks¶

• Tab-complete works on nicknames. use it.

• Highlight when people say your name

• Symbols are not part of names; they mark status in channel

• Logging (expect it); `/set autolog on`

• chanserv and nickserv are good bots to know

  • hamper is also a bot

Screen & Irssi Hints¶

• Paste with ctrl+shift+v

  • PuTTY defaults to right-click to paste

• to get back, screen -dr IRC

• Can you use man screen to find out what the d and r flags mean?

SCREEN(1)                                                               SCREEN(1)

NAME
       screen - screen manager with VT100/ANSI terminal emulation

SYNOPSIS
       screen [ -options ] [ cmd [ args ] ]
       screen -r [[pid.]tty[.host]]
       screen -r sessionowner/[[pid.]tty[.host]]
Manual page screen(1) line 1 (press h for help or q to quit)

Etiquette¶

• Lurk more

• Don’t ask to ask

  • Lure help out of hiding with tasty details of problem

• Show that you’re worth helping

• Read the topic

  • /topic
  • Output only shows up in your channel, not to everyone else

• Pastebin code

• Choose your nick carefully

Terminology¶

• ping/pong
• flapping

• tail

• hat

• nick

• netsplit

• kick/ban/k-line

• common emotes

  • o/ AND \o high fives
  • /me & means afk

Review¶

• What’s Linux?

• How do you open a terminal emulator?

  • this varies between window managers

• I have the script test.py. How do I run it??

• How do you list all the files in the current directory?

• Give 2 ways to change directory to your home directory.

• How do you start an irc client?

  • How often should you need to start your IRC client?

• How do you reconnect to a screen session?

• Give an example of something which you should not do in IRC