Intro to the Command Line

However, it is important to note that even experienced users often cut and paste commands (from a guide or manual) into the command-line terminal; they do not memorize them.

It is important, of course, to know how to use the command-line terminal - and anyone who can manage typing, backspacing, and cutting and pasting can manage the command-line terminal (it is not more difficult than that).

from “Using The Terminal” - https://help.ubuntu.com/community/UsingTheTerminal

Principles

Small parts, loosely joined
Each tool should do one thing well
Don’t be superstitious
Things should be as simple as possible, but not any simpler
Don’t repeat yourself
Don’t remember anything you don’t have to
There aren’t really any shortcuts to learning stuff
Better tools give you: more power, more flexibility, more fun, less fear; but they come at a cost
Don’t lose sight of the forest for the trees

Basic Commands

Essentials

man

sudo

locate

System Information Commands

du -s

ifconfig

whereis

which

File & Directory Commands

cp [-Rv]

ln [-s]

ls [-alsh]

mkdir [-p]

pwd

rm [-rf]

Input / Output Commands

streams: 2>&1, >, >>, <, |

$()

cat

echo

grep

head

less

tail

Communication

curl

ping

rsync

scp

sftp

ssh

wget

Processes

Ctrl-z

disown

jobs

ps aux

top

Other Stuff

Tools

nano

vim

emacs

screen

Programming Languages

Ruby

Python

Perl

Using the Terminal

Save on typing

History: Up Arrow, Down Arrow, tab, ctrl+r, history,
Movement: ctrl+a or Home, ctrl+e or End, ctrl+b (back word)
Deletion: ctrl+k (cursor to $), ctrl+u (^ to $), ctrl+w (back word)

BONUS: Pretty it up

Colors! Start with \e[ then a color code (40's for backgrounds, 30's for foregrounds, mix it up with ;'s), then the letter m. Return to default with \e[0m.

For example:

echo -e "\e[41m\t\e[47m\t\e[44m\t\e[40;33m\tTHESE COLORS DON'T RUN\e[0m"

Copy and paste that fine fellow and absorb an eyeful.

BONUS: Scripting

This is way too deep for a "finding your way around" class. Besides, you should use Ruby (or Python or Perl) if it's anything complex. Seriously, Bash is good for one liners, but if you’re going to have to maintain it, unless you have compelling reasons to the contrary, use a “real” scripting language. Preferably an object oriented one with a healthy standard library.

Ruby - http://mislav.uniqpath.com/poignant-guide/

Python - http://learnpythonthehardway.org/index

Perl - http://perldoc.perl.org/perlintro.html