Appendix A Introduction to Using Linux

Objectives Linux introduction Commands-Line Interface Files and Directories Basic Commands The password Command The man Command The ls Command The cp Command The mv Command The rm Command The cd Command The mkdir Command I/O Redirection and Pipe Operators Shell Variables Text Editing File Access Permissions Script Files Searching Data in Files Evaluating Expressions Connecting to a Remote Linux Server, cs3 Dr. Garrido and el al Textbook ©2012 Jones & Bartlett Learning, LLC

Connecting to a Remote Linux Server, cs3 Please refer to Appendix A in the Course Textbook or follow the steps from the link below. Download SSH Secure Shell Client Go to Go to Software Downloads After downloading, execute the install program SSH Secure Shell Client (icon will be on your desk top) Click on the SSH Secure Shell Client

Download SSH Secure Shell Client Download the SSH (Secure Shell File Transfer (SFTP)); – from KSU UITS / Software Downloads. (SSH consist of SSH Secure Shell Client and SSH File Transfer),/ Note: for this course, you need to use SSH Secure Shell Client to login to CS3 server. Default: SSH Secure Shell Client icon will be install on your desktop Windows.

Login to Linux cs3 server Click on Profiles folder on the tool bar Select Add Profiles Give a name: cs3 Edit Profiles cs3 Host name: cs3.kennesaw.edu User name: your KSU netid Ok Go to Profiles Select cs3 Enter Password: Temp password: new123 Login to cs3 server, then Change password: $passwd

The CS3 Server A Computer Science Department server All assignments are to be developed on the CS3 server Access to CS3 is via a command-level interface using a ‘terminal’ utility, such as SSH on Windows

Connecting to CS3 Server Make sure you are connected to Internet Start SSH (Secure Shell Client) to connect to a remote Unix server Type cs3.kennesaw.edu Logon to Linux on the CS3 server Start using the appropriate Linux shell

Window for SSH Shell Client

Logged in to cs3 Linux server

Running Simulation Models on CS3 Use the 'mkdir' command to make a new directory under the current directory, then change to the new directory with the 'cd' command. $ mkdir myos $ cd myos Copy two files from the /home/jgarrido/psim3 directory to your working directory: – the corresponding simulation model ( batch.cpp ) – the psim3c script file $ cp /home/jgarrido/psim3/batch.cpp myos $ cp /home/jgarrido/psim3/psim3c myos

Steps to Run a Simulation Model on cs3 (Cont.) Change to the new directory: $ cd myos Compile and link the simulation model: $./psim3c batch.cpp Run the model (output on the screen): $./batch.cpp //FN.ccp $ ls –lt //to see which file is ready to be exeucted. The list //should show files and executed file (in different color), that the one you need to Run $./psim3 // follow the file name $ a.out Run the model, redirect the output to a file $./a.out |tee res1.txt View the output file $ more res1.txt

Steps to Run a Simulation Model on cs3 (Cont.) Run the program again to change one or more parameters in the model Compile and link again (if necessary) Run the program again Get the results in another file After the third simulation run, exit Unix. Use SSH File Transfer from your PC to get the output files

‘ls’ Command List files and subdirectories in current directory or specified directory $ ls The long listing is produced with the -l option: $ ls -l $ ls -lt | more

To edit a text file To edit a text file (C++ source file), use the “nano” editor. For example, to edit “batch.cpp” type the following command: $nano batch.cpp

‘man’ Command To get a short online manual or documentation on the specified command $ man ls (help with ‘ls’) $ man cd (help with ‘cd’) The space key shows the next page

Make and Change Directory To make a new directory under your current directory: $ mkdir mydir To change to a directory: $ cd mydir (change to mydir) or $ cd myos (change to myos)

Directories The system root directory is denoted as a slash (/) An absolute path denotes the position of a file in the file structure /home/jgarrido/psim3/batch.cpp The current working directory is denoted as dot (.), The parent of the current directory as dotdot (..)

Show Current Working To display the current working directory: $ pwd To return to your home directory: $ cd

The ‘script’ Command Open a new record session (log session) to a text file: $ script mysession.txt To terminate the session, type the ‘exit’ command

Introduction to Linux Linux is a multiuser, multitasking operating system that is a variant of Unix and preforms many of the same functions. Linux is to purchase a Linux distribution, an organized bundle that includes the kernel (core of the operating system) and a large set of utility programs with installation utility. Dr. Garrido and el al Textbook ©2012 Jones & Bartlett Learning, LLC

Introduction to Linux A user interacts with Linux using one of several available interface that are grouped into two categories – A text-based command line interface – A graphical user interface (GUI) Linux has several graphical user interface available, such as GNU Network Object Model Environment (GNOME) and the K Desktop Environment (KDE) Dr. Garrido and el al Textbook ©2012 Jones & Bartlett Learning, LLC

What is Linux? Linux is, in simplest terms, an operating system. It is the software on a computer that enables applications and the computer operator to access the devices on the computer to perform desired functions. Linux is very similar to other operating systems, such as Windows and OS X. Linux operating system represented a $25 billion ecosystem in Since its inception in 1991 and in 2011 earn up to 49 billion. Linux has grown to become a force in computing, powering everything from the New York Stock Exchange to mobile phones to supercomputers to consumer devices.

Linux Overview  Linux is developed collaboratively, meaning no one company is solely responsible for its development or ongoing support.  Companies participating in the Linux economy share research and development costs with their partners and competitors.  This spreading of development amongst individuals and companies has resulted in a large and efficient ecosystem and unheralded software innovation.  Over 1,000 developers, from at least 100 different companies, contribute to every kernel release.  In the past two years alone, over 3,200 developers from 200 companies have contributed to the kernel--which is just one small piece of a Linux distribution.

Where is Linux Linux Uses in: Desktop, Laptops, Phones, small devices, Mainframes, supercomputers Browser like Firefox, servers, Sony TV, Reader, Digital Recording devices. Many of the popular Web 2.0 services on the Internet, such as Twitter, Linked In, YouTube, and Google all rely on Linux as their operating system. As new web services arrive in the future, Linux will increasingly be the platform that drives these new technologies.

Linux Began On August 25, 1991, a Finn computer science student named Linus Torvalds made the following announcement to the Usenet group comp.os.minux Torvalds built the core of the Linux operating system, known as the kernel. A kernel alone does not make an operating system, but Stallman's GNU tools were from a project to create an operating system Torvalds' matching of GNU tools with the Linux kernel marked the beginning of the Linux operating system as it is known today. :

The term runlevel refers to a mode of operation in one of the computer operating systems that implement Unix System V-style initialization.System V Conventionally, seven (7) runlevels exist, numbered from zero to six; though up to ten, from zero to nine, may be used. S is sometimes used as a synonym for one of the levels. Only one "runlevel" is executed on bootup - run levels are not executed sequentially, i.e. either runlevel 2 OR 3 OR 4 is executed, not 2 then 3 then 4. "Runlevel" defines the state of the machine after boot. Different runlevels are typically assigned to: single-user mode multi-user mode without network services started multi-user mode with network services started system shutdown system reboot Run Levels Run Levels Weblink

Kernel All operating systems have kernels, built around the architectural metaphor that there must be a central set of instructions to direct device hardware, surrounded by various modular layers of functionality. The Linux kernel is unique and flexible because it is also modular in nature. Modularity is desirable because it allows developers to shed parts of the kernel they don't need to use. Typically a smaller kernel is a faster kernel, because it isn't running processes it does not need.

Linux Environments The windows, menus, and dialog boxes most people think of as part of the operating system are actually separate layers, known as the windowing system and the desktop environment. These layers provide the human-oriented graphical user interface (GUI) that enables users to easily work with applications in the operating system and third-party applications to be installed on the operating system. There are tools and code libraries available that let application developers to more readily work with these environments