Linux and Java Basics

What is Linux?

• Operating system by Linus Torvalds that was a clone of Unix (thus Linux)

• Free and open source – this is the reason for its success

• Unix and Linux now both very closely related

Where is Linux?

• iOS and OSX (Linux like Unix called BSD)• Android (Linux)• Our server• Deep Blue, Watson, CERN’s LHC• Military tanks, missile systems, satellites,

robots, etc…• ~65-80% all internet servers and security

devices

Supercomputing?

What’s with all this text only non-sense?

Command Line Interface

Every operating system needs to be able to take instructions. The interface for all OSs is done is called the command line.

Other names you might see:• Shell• Command prompt• CLI• Console / Terminal

But… why are we learning it?

• The GUI is heavyweight – a robot has limited computing power and using it on running a GUI is a huge waste– Interacting with most of these systems is

command line only

• Understanding this is underneath all the shiny stuff helps you understand computing

• Will allow you to do advanced non-programming things on your computer

Connecting to Aegis

• ssh – secure shell connection. How you would work with a robot’s operating system using your computer

Basic Linux Commands - Navigation

• ls – list. Shows the files in the current or specified directory

• cd – Change Directory. Switches you to a different directory.

• rm – ReMove. Removes a file(s)• mv – MoVe. Moves a file(s) from one location to

another• cp – CoPy. Copies a file(s) from one location to

another• mkdir – MaKe DIRectory. Makes a new directory.

Anatomy of a Command

Tab

TAB is your friend!

Pressing tab on an incomplete command or argument• Finishes it for you (if only 1 possibility)• If more than 1 possibility, double tab lists options• Saves so much typing and memorization!• You should press it… (reasonably) a lot

Your Turn

Now, you try!

ls

cd

rm

More Commands!

• pwd – Present Working Directory. Display the full path of the current directory you are in

• cat – concatenate. Most used for quickly displaying contents of a file, but can be used to add stuff to ends of files.

• clear – puts the last line at the top so you have a fresh screen

• man <program name> - get the manual for a specific program, e.g., man ls

Wildcards

Wildcard – a character that can be used as a substitute for some set of other characters

• * - match anything• ? – match exactly 1 character of any kind

Wildcards

F! YEA JAVA!

Compiling and Running Java Programs