Linux/Mac OS X Basics
for CS 115 at Sonoma State University

• Some activities (e.g., editing, storing materials on a file server) will utilize a graphical user interface (a GUI), with which you can use a mouse to point at windows and menus and then click your mouse to accomplish various tasks.

• Some activities (e.g., running programs) require work in a text-oriented environment called a Terminal window.

Introduction

This laboratory exercise provides initial practice with both of these environments, in the context of doing several tasks that will be used almost every day of the semester. Basic tasks fall into three main categories.

• Working with a Terminal window: focusing on some commands to set up your work on a lab workstation.
• Setting up a file server: creating/organizing directories/folders for long-term storage of files.
• Preparing for next steps: copying files and organizing work in anticipation of programming in C in the next lab and beyond.

More information about various parts of this lab is available through two readings:

• Reading on Linux/Mac OS Basics
• Reading on Editing and Storing/Retrieving Files

Work Started in Class

Working with a Terminal Window

Although using a mouse provides many convenient capabilities on modern computers, some tasks cannot be done using a mouse to point and click, and other tasks are cumbersome with a mouse only. In particular, most C-based work involves use of a Terminal window, because this environment allows a user to take advantage of many powerful capabilities of the Linux and Mac OS X operating systems.

This lab starts with some basics.

• opening a Terminal window.
• using basic commands.
• copying between windows

Opening a Terminal Window

1. When working with programs (e.g., running them), you will need to work with a Terminal window—an area where you type commands, and the machine responds. Opening and using a Terminal window can be done in either of two ways:

   • If the Terminal Window logo is visible at the bottom of the screen, click on it.
   • If the Terminal Window logo does not appear on the screen,
     • Click on the "Finder" icon at the bottom left of the screen.
     • When a new window appears, click on "Applications" on the left panel.
     • Scan down the options to click on "Utilities" and then "Terminal.app".

Once the Terminal window opens, move your mouse to the window and click, so you will be able to type within that window.

Some Basic Commands

With the Terminal window open, we can experiment with several commands. At first, the commands may duplicate tasks that you could do with a mouse (point-and-click). However, using the Terminal window now will provide initial practice, anticipating later work (e.g., in the next lab) that requires using a Terminal window.

2. When a Terminal window opens, it recognizes the folder/directory where you logged in—a home directory for "student". To determine the full name of this directory, type

            pwd
          

   pwd stands for "print working directory".

   After typing this command, the computer will identify a directory where it is operating.

   • If the computer responds

           /Users/student/
         

     the computer is looking at the directory designed as the normal starting place for user student, and you can move on in the lab.

   • If the compuer does not respond /Users/student?, then type

               cd
             

     This is a simple command that takes you to the starting place for user student

   Once you see the response /Users/student, we can decipher what this response means. As explained in the Reading on Directories, files on Linux and Mac OS machines are organized into a hierarchy:

   • / or "root" is at the base of the hierarchy
   • Users lies one level below the root
   • student is a folder or directory within Users

3. To see what folders and/or files are set up within a student account, type

         ls
       

   or type the longer, more complete, version

           ls -l
         

   1. What files and directories are listed as being within the student home directory? (The results will depend on which workstation you are using.)
   2. What additional information is listed when you add -l to the ls command?

4. To explore further, type

             cd ..
           

   Here, cd means "change directory", and two dots (..) represents the directory just above the current one in the hierarchy.

   Again, use pwd and ls to determine the location being viewed in the Terminal window and the directories within this location. (You should see student as one of the directories.)

5. Again, type cd .. with pwd and ls to determine what lies above /Users in the hierarchy.

   1. What files are listed?
   2. What happens if you type cd .. again? Why do you think you obtain this result?

6. Return to your home directory with either of the following two commands

                 cd
                 cd Users/students
               

7. Move to your Desktop

                 cd Desktop
               

8. As an experiment, move back to the student home directory and then try moving to Desktop, but type "desktop" with a lower-case "d". Describe what happens.

9. Again from the student home directory, type

                 cd D
               

   1. Now hit the Tab key. What happens?
   2. Press the Tab key a second time, and explain what happens.
   3. Now type "e", so the line reads

                cd De
              

      and hit the "tab" key. What happens? Why?

10. Move again to the Desktop and use ls to see what files and/or directories are present. (Likely, these are left from previous users.)

    Within the Desktop, create a directory for your current work on this Workstation. Although you can use any name you wish (as long as the name has not been taken by someone else, I recommend you use a name "115" followed by your name. (You might use a dash in the name, but do not use spaces or other punctuation.) A sample command might be:

                  mkdir 115-walker
                

    Use the ls command to check that this new directory was created has you expected.

Copying Between Windows

Linux and Mac OS X allow you to cut and paste between windows.

• For Linux, you can use the left and middle mouse buttons without using the control Ctrl key.
• For Mac OS X, you can highlight a section of text with the left mouse button, and then use Open Apple/Command X or Open Apple/Command C to cut or copy text, respectively, and then Open Apple/Command V to paste.

11. Consider the following line, that when typed into a Terminal window, prints the time and date

      date +'%I:%M %p on %A, %B %d, %Y'
    

    To use this command, you could type the entire line into a workstation, but that would be tedious and error prone. Instead, try the following:

    • Highlight the above line using the left mouse button, and select the material as described in today's reading.

    • Move the mouse to the terminal window, and paste the line into the terminal, again using the process described in today's reading. (You may need to hit the return key after pasting the copied line.)

    Note: On Linux, there is no need to use the control Ctrl key.

Setting Up the File Server

For technical reasons, all students log into CS Lab machines at SSU under a "student" account. This provides fine access for active work, but work cannot be saved on these machines over the long term. Rather, the department supports a file server for long term file storage. The following instructions outline how to access and set up your account on the departmental server.

setting Your Password in the Server

The CS file server has been set up, so that you have an account with a username that usually is your first initial and last name. (If that username already belongs to someone else, some variation is possible—see me for details.) The password when you first log in is your student ID. For security, you should log into the server once and change your password to something more private.

12. Log into the CS file server as follows:

    • In a Terminal window, type

                ssh  username@blue.cs.sonoma.edu
                

      where "username" is likely your first initial and last name. (See me for details.)
    • Enter your SSU student ID as your password.
    • Once logged in, type

                  passwd
                

    • You will be asked for your old password (currently your student ID).
    • Next type in a new password twice to confirm .
    • If no errors are reported, you are done. (See the instructor if troubles arise.)
    • Log out of the server by typing

                  logout
                

Working with the Server

13. To store (and retrieve) files from the departmental file server, you first must connect to the server in four steps:

    • Move the mouse away from other windows and click.
    • Type "command-k"
    • Enter the connection string: afp://blue.cs.sonoma.edu
    • Enter your departmental username and password

Although you are free to organize your files on the server in any way you wish, the following is recommended:

14. Once connected to your account on the server, create a directory for this course:
    • Click on the server window.
    • Click on the "File" menu for the Finder (in the upper left of your screen).
    • Click on the option for "New Folder"
    • Label the newly created folder "CS 115" or equivalent
15. Within the CS 115 folder, create four additional subfolders, following the same basic process you have just used:
    • Folder "labs" for collaborative work you will do with a partner during class sessions
    • Folder "projects" for additional collaborative work
    • Folder "supplemental-problems" for assignments you will be working on alone.
    • Folder "current-work" for labs in progress.

With a "current-work" folder, you could start each session by connecting to the departmental server and copying your recent work to the lab workstation. This might be an easy way to pick up work where you left off from a previous session.

Preparing for Next Steps

Looking ahead to later labs and activities throughout the semester, two actions may help streamline your work. Although these steps are optional, they are recommended as preparation for later in the course (e.g., for the next lab).

Copying a "Makefile" to your Directories

When working with the Scribbler 2 robots in a few days, logistics will be relatively simple if you download a file, and place copies in several directories.

16. Download the file Makefile to the working directory you created in Step 10. Be sure that the file is stored under the name Makefile, with an upper-case M.

17. Open a connection to your account on the departmental file server. Then

    1. Click on the Makefile in your Desktop 115 directory.
    2. Holding the mouse button down, copy it to each of your

Checking Settings on Aquamacs

If you have used a computer to help write a document, you likely have used an editor of some type. The Aquamacs editor provides appropriate functionality for developing programs, while maintaining a reasonably elementary user interface. Thus, Aquamacs is recommended for use in this section of CS 115.

Before writing programs, however, can be helpful to check that a few capabilities in Aquamacs are turned on to aid in the program-development process.

18. Starting Aquamacs: At the bottom of the screen, you might find an icon for Aquamacs.

    • If so, just click on the icon to start the editor.
    • If the appropriate editor icon is not present,
      • Click on the "Finder" icon at the bottom left of the screen.
      • When a new window appears, click on "Applications" on the left panel.
      • Scan down the names given to find "Aquamacs.app", and click on the desired option.
    • To create a new file with the editor, click on the "File" menu at the top-left of the screen and then click the "New File" option.
    • To save the file,
      • Use the "File" menu to select save.
      • When a directory appears, click on "Desktop" and the directory/folder you wish to work with.
      • Enter the desired name of the file, and click "Save".