ssh cs##.cs.iusb.edu -l username -XY

where ## means a 2-digit number between 01 and 03. You may have to try several numbers to find one that works because some of these computers may be booted in Windows or MacOS, in which case they will not respond to this command. Replace "username" with the name of your account. This opens a remote secure session on the machine that you specified. You will be prompted for a password.

Here is an example of a connection being established.

cs##.cs.iusb.edu

where ## means a 2-digit number between 01 and 03. Make sure that the connection type is SSH, like in this example.


You may be asked to confirm that you want to connect to this machine by a security alert system the first time you log on to a particular host, like in this example.


Just answer yes. A terminal window will open where you will be prompted to enter your username and password, like in this example.


These should be your usual IT information. You may have to try several computer numbers until one works (see Mac section above).

On your home computer, you may want to bookmark the session information for easy access. You can enter the username and remote host name, then give it an easy name to remember in the Saved Sessions box, and click Save. After that you'll be able to launch the session again by double-clicking on the bookmark name in the list. It is not recommended to save the password.

To make it easier to save the terminal, you can click on the little icon in the top-left corner of your putty window, and from the pop-up menu, choose "Change Settings". There you can click on Logging, and check the "Printable output" option or the "All session output". Then hit the Browse button to choose where to save the session under the name "putty.log" or whatever name you choose for it. That file, that you can rename later as "lab0term.txt" or "hw1.txt" or whatever name is appropriate for your session, will be part of what you turn in for this lab and for most of the labs and homework assignments.

Your working (or current) directory when you login is called your home directory. It is a folder named after your username and located in a folder called /home. Most commands will apply by default to files in your working directory, and a little later you'll learn how to change it. To see the path of the working directory, type the command pwd, then hit the Enter key. It stands for Path of the Working Directory.

A command is a small executable that performs some operation involving the file system, the processes, or the operating system. For example, the command ls stands for "list" and will display a list of the files residing in the current working directory. Try it.

Commands can have arguments specifying what they apply to. For example, for the command ls, we can ask it to list the files in a different directory than the current one by providing this other directory as an argument (/var/log/ in the following case):

ls /var/log

Commands can also have options that modify the way they are executed. For example, an option for the command ls would be "-l" (lowercase El) that makes it display the list of files with a long list of properties or attributes:

ls /var/log -l

Arguments and options are usually flexible. Try the previous command again while swapping the places of the option and the argument. The result should be the same.

Options can be provided separate, or grouped together. For example, the option -a for the command ls will also display hidden files. If we want to run this command with both the options -a and -l, we can have them both separated by a space, or use -al instead. Thus, the following three commands should be equivalent (make sure they are):
ls -a -l
ls -l -a
ls -al

If you are not sure about what a command does and what options can be used with it, the easiest way to find out is with the command "man", which is short for manual (q to exit):
man ls

Commands we'll use below:

• ls - displays the list of files in a directory
• cd - changes the current working directory
• pwd - displays the path of the working directory
• less - displays the content of a file one page at a time
• mkdir - creates a directory
• pico - simple text editor
• cat - displays the entire content of a file
• cp - copy a file or directory
• rm - remove a file or directory
• man - manual pages (q to exit)
• alpine - email utility

Practical:

• Try out the command ls with and without the option -l. Explore the content of the directory /usr/ using this command without making it your working directory.
• Use the command cd to change your current working directory (change directory) to the /usr directory:

  cd /usr

  and check its content with the command ls. Note: this directory is found at the root (top level) of the entire filesystem on that computer (identified by the slash /). Since it is not a subdirectory of the current working directory, we identify its name starting with the slash. This is called an absolute path.

  Descend into the include subdirectory with the command

  cd include
  

  Note that this directory is directly inside /usr (which should be your current working directory) and for that reason, we do not start its name with a slash. This is called a relative path.

  Repeat the operation to go to one of its subdirectories (your choice). Start again with the directory /lib (absolute path again) and then another subdirectory. To go back up in the path of the current directory you can use

  cd ..

  where the ".." identifies the parent directory (one up) from wherever you are at the moment. A single dot identifies the directory itself.

  Find the path of the directory where you are using the pwd command.

• Use the command less to view the content of one of the files in the folder /usr/include with the .h extension (the file name must be an argument for less). To move around inside the text, use the space, Page Up, Page Down, and the up and down arrow keys. To quit the viewer, type Q (upper or lower case).
• Use the command cd with no arguments to move back to your home directory.
• Create a directory named "c151" under your home directory. The command for this looks like this:

  mkdir c151
  

• Use the command cd to go inside this directory.
• Create a text file using the pico editor. You can do that with the command

  pico lab0pico.txt

• Write a few lines in this file, then save them with the command Ctrl-o. When the program asks you for the file name, just press enter to keep the same name. When you are done, exit the editor with the command Ctrl-x. Note that most useful commands for pico are displayed at the bottom of the window, where the "^" symbol stands for Ctrl.
• Back to the terminal, display the content of this file with the command cat followed by the file name (in the same command). The name of the file should be provided as an argument.


If you typed the command cat without an argument, you'll need to get out of it with Ctrl-c. This command should interrupt whatever command is being executed by the terminal at that moment. It works most of the time.
• Use the command cp to make a copy of this file under a different name. First, find out how to use the cp command using the Linux manual for it. For this, type the command
  man cp
  The manual pages are displayed with the command less, so you can use the same functionality to move around the text (q to exit).
  
• Use this information to make a copy of your file under a different name, such as hw1_copy.txt.
• Use the command rm to remove the file that you have copied.
• Explore the commands that you have just executed using the right-hand-side slider of the terminal window.
  
• The Linux shell helps you type your commands faster. The tab can be used to complete a command that you are about to type. To test this feature, list the content of the /usr directory by typing

  ls /u
  

  without any space after "u", and then without completing the word "usr", type a tab. Note that the shell has completed your command. Without pressing enter, type an "l" (lowercase "el") as if you were going to list the files or folders starting with l, and then press a tab again (you may have to press it twice). Since there are several folders starting with l, the shell will display all the possibilities instead of completing the command. As soon as the command can be completed uniquely, the shell will do it. For example, type an "o" and press a tab again. Since "local" is the only possible completion, the shell will complete it for you. Finish the command by pressing enter.

• Create a subdirectory called week0. Move the file you have created so far into this directory with the following command, where the "/" at the end of week0 indicates that this is the name of a directory

  mv lab0pico.txt week0/

• On a Linux machine, open a gedit separate window by typing the command (the ampersand is important)
  gedit &
  The using the mouse, select the entire content of the terminal (which should copy it, but if that doesn't work, the Edit menu should let you copy), then paste it into gedit with Ctrl-V. Save it under the name lab0term.txt in the directory week0 inside your directory c151. You can also try the "Save contents" option from the File menu.
  
• On a MacOS system, locate the Shell menu at the top of the screen (not of the terminal window) and then do Export Text As... Save the file as lab0term.txt.
  
• On a Windows machine under Putty, if you have turned on the session logging, then you just need to find the file putty.log in the folder that you chose for it, and rename it as lab0term.txt. If you haven't done that, then click on the Putty icon in the top left corner, and choose Copy All To Clipboard. Then open a simple text editor like Notepad++ (do NOT use Word) and paste the content in a new file. Save the file under lab0term.txt.

• You have an email related to your cs account, and your address is username@cs.iusb.edu.
  
• Launch alpine by typing this command (and press enter). Note: some computers might still be running the previous Fedora core. If the command alpine doesn't work, use pine instead.
• If this is the first time you have used alpine, the program will ask you if you want to be registered as a alpine user. Just press Enter.
• To find the content of your inbox, from the main menu (that you can always find with m), press enter or l for list, and then enter again. Your inbox is probably empty for the moment.
  
• Start composing a message by typing c. In the To field insert my email address, dvrajito@cs.iusb.edu. Move between the fields using the arrow keys. In the subject area, type Lab 0. The body of the message should just state your name.
• Attach the file called lab0pico.txt that you have created before. For this, move to the Attachmnt field and type Ctrl-t. This will take you to a file browser that should open in your home directory. Move between file names with the arrow keys. Locate the folder named c151 and when its name is highlighted, press enter.This should take you inside that directory. Do the same for the directory week0. Select the file and press enter.
• Once your email is ready, type Ctrl-x to send it. Alpine will ask for a confirmation and you can just press enter.
• Note that most useful commands under alpine can be found at the bottom of the window, just as for pico. And just the same, "^" means Ctrl.
  

Submit the file lab0term.txt containing the text in the terminal for exercise 2 to Canvas. Under Assignments there is a section called Lab 0 where you can submit it. The lab is due next Tuesday at 11:59pm.