IT 244: Introduction to Linux/Unix - Class 3 Exercise, Tuesday, February 2nd

IT 244: Introduction to Linux/Unix
Class 3 Exercise, Tuesday, February 2nd

When finished: Remember to check with instructor to make sure you are recorded as having completed the class exercise!

Open new CLI window for this exercise. (PowerShell, Command Prompt, PuTTY, Mac Terminal, etc.)

Depending on your app, set "screen buffer" size to something generous, such as at least 1000 lines. We can address this in class, as needed. Be prepared to copy CLI window contents, at exercise end.

Log in to pe15

Run the ssh client
Use the values in the table below to connect to pe15.

In the value for host listed below, the first string, pe15, specifies the machine, on the Unix network, that you will connect to.

ssh configuration parameter	value
protocol	ssh
ssh version	2
ssh port	22
host	pe15.cs.umb.edu
user name	your unix username
Authentication method	password

Enter your password
A dialog box will appear on the screen into which you must type the password for your Unix account.

Create ex and ex03 Directories

Make sure you are in your home directory
```
    cd
```
If your it244 directory was created and it now exists, then go into it. (Otherwise, we'll need to help you set it up.)
```
    cd  it244
```
Create an ex directory
```
    mkdir  ex
```
Go to your ex directory
```
    cd  ex
```
Create an ex03 directory
```
    mkdir  ex03
```
Go to your ex03 directory
```
    cd ex03
```

nano

Run nano creating a text file named today.txt
```
    nano today.txt
```
Practice with nano
Write a few sentences about what you did today.

Use as many of the nano commands, which you see at the bottom of the page, as you can.

The ^ character you see before each letter in the help menu at the bottom of the page tells you to hold down the Control key as you type the letter of the command.

Some important commands do not appear in the menu.

Control + A will take you to the beginning of the line, Control + E will take you to the end of the line, and Control + K will delete the current line.

When you use Control + K, the line you deleted is placed in a buffer.

You can get this line back, pasting it in your current position in the file. using Control + U.
Save the file
```
    Control + O
```
After typing this command, the file name will appear at the bottom of the screen.

Hit Enter, to indicate that this is the correct file name.
Quit nano
```
    Control + X
```
Look at the contents of the file
```
    cat today.txt
```

script

Run script with the --flush option
```
    script --flush
```
Move to your home directory
```
    cd
```
If you run cd without any arguments, it will take you to your home directory.
Determine your current location
```
    pwd
```
You should be in
```
    /home/YOUR_UNIX_ID
```
List the contents of your home directory
```
    ls
```
Quit script
```
    exit
```
Determine your current location
```
    pwd
```
You should be in
```
    /home/YOUR_UNIX_ID/ex/ex03
```
When you run script, a sub-process is generated which contains a new instance of the Bash shell.

Any changes you make to your environment, such as your current location, disappear when you exit script.

Since you started script in your ex03 directory, that is where you will return when you exit.

Any files you created or changed while you were using script will remain as you left them in your script session since they are part of the file system, not your environment.
Look at the typescript file
```
    cat typescript
```
Run script again, adding you new session to typescript
```
    script -a --flush
```
Look at the value of the SHELL variable
```
    echo $SHELL
```
Pay attention to capitalization. Unix is case sensitive.
Quit script
```
    exit
```
Look at the typescript file
```
    cat typescript
```
You should see the echo command you just invoked, along with its results.

Stopping the Execution of a Command

Run a command that cannot finish

To see how this works, we'll try to run ssh using an account on users that doesn't exist.
```
    ssh foo@users.cs.umb.edu
```
If you get a message saying the authenticity of host cannot be established, type "yes".

No password you can enter will allow this command to complete, because you are trying to log into an account that does not exist.
Abort the program
```
    Control + C
```
This is the only way you can get out.

Command Line Editing Practice

Type something at the command line
```
    foo bar bletch
```
Move to the beginning of the command line
```
    Control + A
```
Move to the end of the command line
```
    Control + E
```
Clear the command line
```
    Control + U
```

Use the History Feature

Retrieve the last command
```
    ⇑
```
Retrieve the command before that
```
    ⇑
```
Return to the last command
```
    ⇓
```

Look at a man Page

Run man on ls
```
    man ls
```
Scroll down one screen
```
    Space
```
Scroll down one line
```
    Enter
```
Scroll up one line
```
    ⇑
```
Scroll down one line
```
    ⇓
```
Quit man
```
    q
```

Experiment with apropos

Run apropos on the word "link"
```
    apropos link
```

Use info

Run the info command on the word "link"
```
    info link
```
Display the help menu
```
    h
```
Close the help menu
```
    x
```
Quit info
```
    q
```
Run info without an argument
```
    info
```
You should see the first page of the info system.
Look at the file permission entry
```
    m
```
At the bottom of the screen, you should see the following prompt
```
    Menu item:
```
Enter the "File" then hit the Tab key, then press Enter.
Go to the previous node
```
    p
```
You should see the entry for "Numeric operations"
Return to the File permissions node
```
    n
```
Look at the "Mode Structure" Link

Keep hitting the down arrow until you are on the line with an * and the words "Mode Structure"

Hit Enter

You should see the "Mode Structure" page
Quit info
```
q
```

When finished:

Remember to check with instructor to make sure you are recorded as having completed the class exercise.
To do this:
1. Select/highlight all of the text in your CLI window, from this exercise.
2. Copy that text to the clipboard. Note that usual text copying shortcuts may not -- and likely WILL not -- work!
3. Make sure you are in your Exercise 3 directory:
```
cd /home/YOUR_USERNAME/it244/ex/ex03
```
4. Open a new file for editing:
```
nano ex03_cli.txt
```
5. Paste the copied text into your editing field in nano. Note that usual text pasting shortcuts may not -- and likely WILL not -- work!
6. Save file and exit from nano.