# Découverte d'Ubuntu Linux et son Terminal Bash ## Navigating the Ubuntu GUI > In this exercise, we will familiarize ourselves with the graphical user interface (GUI) of the Ubuntu operating system. ### Task 1: Familiarize Yourself with the Ubuntu Desktop At the log-in screen, click in the password input box, enter `rosindustrial` for the password, and hit enter. The screen should look like the image below when you log in: ![../../_images/ubuntu_desktop.png](https://industrial-training-master.readthedocs.io/en/humble/_images/ubuntu_desktop.png) There are several things you will notice on the desktop: ![../../_images/ubuntu_desktop_details.png](https://industrial-training-master.readthedocs.io/en/humble/_images/ubuntu_desktop_details.png)

1. The gear icon on the top right of the screen brings up a menu which allows the user to log out, shut down the computer, access system settings, etc… 2. The bar on the left side shows running and “favorite” applications, connected thumb drives, etc. 3. The top icon is used to access all applications and files. We will look at this in more detail later. 4. The next icons are either applications which are currently running or have been “pinned” (again, more on pinning later) 5. Any removable drives, like thumb drives, are found after the application icons. 6. If the launcher bar gets “too full”, clicking and dragging up/down allows you to see the applications that are hidden. 7. To reorganize the icons on the launcher, click and hold the icon until it “pops out”, then move it to the desired location.

### Task 2: Open and Inspect an Application Click on the filing-cabinet icon in the launcher. A window should show up, and your desktop should look like something below: ![../../_images/ubuntu_folder_browser.png](https://industrial-training-master.readthedocs.io/en/humble/_images/ubuntu_folder_browser.png) Things to notice:

1. The close, minimize, and maximize buttons typically found on the right-hand side of the window title bar are found on the left-hand side. 2. The menu for windows are found on the menu bar at the top of the screen, much in the same way Macs do. The menus, however, only show up when you hover the mouse over the menu bar. 3. Notice that there are menu highlights of the folder icon. The dots on the left show how many windows of this application are open. Clicking on these icons when the applications are open does one of two things: - If there is only one window open, this window gets focus. - If more than one are open, clicking a second time causes all of the windows to show up in the foreground, so that you can choose which window to go to (see below):

![../../_images/ubuntu_inspect.png](https://industrial-training-master.readthedocs.io/en/humble/_images/ubuntu_inspect.png)

### Task 3: Start an Application & Pin it to the Launcher Bar Click on the launcher button (top left) and type gedit in the search box. The “Text Editor” application (this is actually gedit) should show up (see below): ![../../_images/ubuntu_start_application.png](https://industrial-training-master.readthedocs.io/en/humble/_images/ubuntu_start_application.png) Click on the application. The text editor window should show up on the screen, and the text editor icon should show up on the launcher bar on the left-hand side (see below): ![../../_images/ubuntu_application_pin.png](https://industrial-training-master.readthedocs.io/en/humble/_images/ubuntu_application_pin.png)

1. Right-click on the text editor launch icon, and select “Lock to Launcher”. 2. Close the gedit window. The launcher icon should remain after the window closes. 3. Click on the gedit launcher icon. You should see a new gedit window appear.

## Le Terminal Linux > In this exercise, we will familiarize ourselves with the Linux terminal. ### Starting the Terminal

1. Pour ouvrir le Terminal, recherchez le programme "terminator" ou cliquez sur l'icône:
    
    [![63008829.png](https://innovation.iha.unistra.fr/uploads/images/gallery/2023-09/scaled-1680-/63008829.png)](https://innovation.iha.unistra.fr/uploads/images/gallery/2023-09/63008829.png)
2. Create a second terminal window, either by:
    
    
    - Right-clicking on the terminal and selecting the “Open Terminal” or
    - Selecting “Open Terminal” from the “File” menu
3. Create a second terminal within the same window by pressing “Ctrl+Shift+T” while the terminal window is selected.
4. Close the 2nd terminal tab, either by:
    
    
    - clicking the small ‘x’ in the terminal tab (not the main terminal window)
    - typing `exit` and hitting enter.
5. The window will have a single line, which looks like this:
    
    `ros-industrial@ros-i-humble-vm:~$`
6. This is called the prompt, where you enter commands. The prompt, by default, provides three pieces of information:
    
    
    1. *ros-industrial* is the login name of the user you are running as.
    2. *ros-i-humble-vm* is the host name of the computer.
    3. ~ is the directory in which the terminal is currently in. (More on this later).
7. Close the terminal window by typing `exit` or clicking on the red ‘x’ in the window’s titlebar.

### Navigating Directories and Listing Files #### Prepare your environment

1. Open your home folder in the file browser.
2. Double-click on the `ex0.3` folder we created in the previous step.
    
    
    - *We’ll use this to illustrate various file operations in the terminal.*
3. Right click in the main file-browser window and select “Open in Terminal” to create a terminal window at that location.
4. In the terminal window, type the following command to create some sample files that we can study later:
    
    
    - `cp -a ~/industrial_training/exercises/0.3/. .`

#### ls Command

1. Enter `ls` into the terminal.
    
    
    - You should see `test.txt`, and `new` listed. (If you don’t see ‘new’, go back and complete the [previous exercise](https://industrial-training-master.readthedocs.io/en/humble/_source/prerequisites/Exploring-the-Linux-File-System.html)).
    - Directories, like `new`, are colored in blue.
    - The file `sample_job` is in green; this indicates it has its “execute” bit set, which means it can be executed as a command.
2. Type `ls *.txt`. Only the file `test.txt` will be displayed.
3. Enter `ls -l` into the terminal.
    
    
    - Adding the `-l` option shows one entry per line, with additional information about each entry in the directory.
    - The first 10 characters indicate the file type and permissions
    - The first character is `d` if the entry is a directory.
    - The next 9 characters are the permissions bits for the file
    - The third and fourth fields are the owning user and group, respectively.
    - The second-to-last field is the time the file was last modified.
    - If the file is a symbolic link, the link’s target file is listed after the link’s file name.
4. Enter `ls -a` in the terminal.
    
    
    - You will now see one additional file, which is hidden.
5. Enter `ls -a -l` (or `ls -al`) in the command.
    
    
    - You’ll now see that the file `hidden_link.txt` points to `.hidden_text_file.txt`.

#### `pwd` and `cd` Commands

1. Enter `pwd` into the terminal.
    
    
    - This will show you the full path of the directory you are working in.
2. Enter `cd new` into the terminal.
    
    
    - The prompt should change to `ros-industrial@ros-i-humble-vm:~/ex0.3/new$`.
    - Typing `pwd` will show you now in the directory `/home/ros-industrial/ex0.3/new`.
3. Enter `cd ..` into the terminal. \* In the [previous exercise](https://industrial-training-master.readthedocs.io/en/humble/_source/prerequisites/Exploring-the-Linux-File-System.html), we noted that `..` is the parent folder. \* The prompt should therefore indicate that the current working directory is `/home/ros-industrial/ex0.3`.
4. Enter `cd /bin`, followed by `ls`.
    
    
    - This folder contains a list of the most basic Linux commands.  
        *Note that `pwd` and `ls` are both in this folder.*
5. Enter `cd ~/ex0.3` to return to our working directory.
    
    
    - Linux uses the `~` character as a shorthand representation for your home directory.
    - It’s a convenient way to reference files and paths in command-line commands.
    - You’ll be typing it a lot in this class… remember it!

*If you want a full list of options available for any of the commands given in this section, type `man ` (where `` is the command you want information on) in the command line. This will provide you with built-in documentation for the command. Use the arrow and page up/down keys to scroll, and `q` to exit.*

### Altering Files #### mv Command

1. Type `mv test.txt test2.txt`, followed by `ls`.
    
    - You will notice that the file has been renamed to `test2.txt`.  
        *This step shows how `mv` can rename files.*
2. Type `mv test2.txt new`, then `ls`.
    
    - The file will no longer be present in the folder.
3. Type `cd new`, then `ls`.
    
    - You will see `test2.txt` in the folder.  
        *These steps show how `mv` can move files.*
4. Type `mv test2.txt ../test.txt`, then `ls`.
    
    - `test2.txt` will no longer be there.
5. Type `cd ..`, then `ls`.
    
    - You will notice that `test.txt` is present again.  
        *This shows how `mv` can move and rename files in one step.*

#### cp Command

1. Type `cp test.txt new/test2.txt`, then `ls new`.
    
    - You will see `test2.txt` is now in the `new` folder.
2. Type `cp test.txt "test copy.txt"`, then `ls -l`.
    
    - You will see that `test.txt` has been copied to `test copy.txt`.  
        *Note that the quotation marks are necessary when spaces or other special characters are included in the file name.*

#### rm Command

1. Type `rm "test copy.txt"`, then `ls -l`.
    
    - You will notice that `test copy.txt` is no longer there.

#### mkdir Command

1. Type `mkdir new2`, then `ls`.
    
    - You will see there is a new folder `new2`.

#### touch Command

1. Type `touch ~/Templates/"Untitled Document"`.
    
    - This will create a new Document named **“Untitled Document”**

*You can use the `-i` flag with `cp`, `mv`, and `rm` commands to prompt you when a file will be overwritten or removed.*

#### Editing Text (and Other GUI Commands)

1. Type `gedit test.txt`.
    
    - You will notice that a new text editor window will open, and `test.txt` will be loaded.
    - The terminal will not come back with a prompt until the window is closed.
2. There are two ways around this limitation. Try both…
3. **Starting the program and immediately returning a prompt:**
    
    1. Type `gedit test.txt &`.
        
        - The `&` character tells the terminal to run this command in “the background”, meaning the prompt will return immediately.
    2. Close the window, then type `ls`.
        
        - In addition to showing the files, the terminal will notify you that `gedit` has finished.
4. **Moving an already running program into the background:**
    
    1. Type `gedit test.txt`.
        
        - The window should open, and the terminal should not have a prompt waiting.
    2. In the terminal window, press Ctrl+Z.
        
        - The terminal will indicate that `gedit` has stopped, and a prompt will appear.
    3. Try to use the `gedit` window.
        
        - Because it is paused, the window will not run.
    4. Type `bg` in the terminal.
        
        - The `gedit` window can now run.
    5. Close the `gedit` window, and type `ls` in the terminal window.
        
        - As before, the terminal window will indicate that `gedit` is finished.

#### Running Commands as Root

1. In a terminal, type `ls -a /root`.
    
    
    - The terminal will indicate that you cannot read the folder `/root`.
    - Many times you will need to run a command that cannot be done as an ordinary user, and must be done as the “super user”
2. To run the previous command as root, add `sudo` to the beginning of the command.
    
    
    - In this instance, type `sudo ls -a /root` instead.
    - The terminal will request your password (in this case, `rosindustrial`) in order to proceed.
    - Once you enter the password, you should see the contents of the `/root` directory.

***Warning**: `sudo` is a powerful tool which doesn’t provide any sanity checks on what you ask it to do, so be **VERY** careful in using it* *https://industrial-training-master.readthedocs.io/en/humble/\_source/prerequisites/Navigating-the-Ubuntu-GUI.html*