2CS21 TUTORIAL 1 (PART 2)

Continue the interactive terminal session by following the instructions given on this web page.

1. SIMPLE COMMANDS

When typing UNIX commands always use lower-case letters. Note also that the typographical conventions given below are used in the following pages:

Format	Meaning
plane text	You type the text exactly as shown. For example: `more myFile' means that you should type exactly these characters.
italic text	You supply the text. For example: `more fileName' means that you type "more" followed by a file name of your choice.
	Press the "return" key.
	Hold down the "CTRL" key while you press the "D" key.

Try each of the following commands at the "dollar" prompt.

$ date

$ cal

$ cal 1997

$ cal 9 1752

Note that the result produced by the last command is not an error. When England switched from the Julian to the Gregorian calendar in September,1752, 11 days were removed from this month. There were riots in the streets with people chanting "give us back our 11 days"!

More information can be found on changing your password in the appropriate section of the "Computer Science Introductory Guide".

3. YOUR HOME DIRECTORY

When you login you are automatically placed in your home directory. The name of your home directory depends upon your username. To find out the name of your home directory use the pwd (print working directory) command as follows:

$ pwd

This tells you the full path name of your home directory. To display the names of the files in your directory use the ls (list) command:

$ ls

Remember that, at present, you have no directory structure and no files - you only have an empty directory Mail and a directory WinDesktop conatining various window management files, both have been created by the system administrator. The Mail directory is associated with the email system, you will use it to store email messages which you wish to keep (when you get some). For the time being you can safely ignore the contents of the WinDesktop directory.

4. CREATING A SIMPLE TEXT FILE

A "quick and dirty" way of creating a text file is to use the cat command coupled with the greater-than output redirection operator. Try the following:

$ cat > myFile some text

You have created a text file, called myFile, in your home directory. Use ls to check that it is there. Now try:

$ more myFile

or simply:

$ cat myFile

The more command calls a "filter" for examining continuous text, one screenful at a time. The cat simple "scrolls" through text files. The distinction is not always apparent when viewing small files that can easily fit onto a single screen. There is also a command less which forefills a similar function to more.

Now make a copy of your "myfile", called myFile2 as follows:

$ cp myFile myFile2

and name the original "myFile" with "myFile1" using the mv (move) command:

$mv myFile myFile1

Investigate the effect using ls.

5. WORKING WITH DIRECTORIES

It is a good idea to organise your file store in a logical manner. We do this by creating a hierarchy of directories under which related data can be gathered. Type the following to create a working directory called 2cs21:

$ mkdir 2cs21

Use "ls" to determine the effect. To distinguish between directory names and file names try:

$ lsf

The lsf command appends a / character (forward slash) to directory names. We can copy or move files from our current directory into the new directory using the "cp" and "mv" commands, however, we must indicate the path to the new directory. We can do this using relative path names. For example:

$ cp myFile1 2cs21/.

Note that the dot is used for convenience where we wish to keep the name of the original file. Copy both your "myFile" files to the new directory using the cp command with appropriate arguments. To check that the copies have been made, change directory to your 2cs21directory using the cd command:

$ cd 2cs21

and then use ls. You should now have a directory structure which can be conceptualised as shown below:

Change back to your (top level) home directory. You can do this simply by typing:

$ cd

without specifying a path (the default path is the relative path from your current directory to your root directory). Now remove your two "myFiles" from the root directory thus:

$ rm myFile1

$ rm myFile2

or

$ rm myFile1 myFile2

Be very careful when removing files, once removed it is extremely difficult to get them back (if at all)! If desired a directory can be removed using the command rmdir although this will only work if all files and sub-directories contained in the directory have previously been removed.

For further information regarding files and directories refer to the appropriate sections in the "Introductory Guide".

6. TEXT EDITING

Stay in your root directory. Now you are going to copy a text file from another directory under a different user name into your 2cs21 working directory that you have just created, and edit it using a type of program called a text editor. The particular text editor program that you are going to use is called "ved" (visual editor). It is necessary to familiarise yourself with at least one text editor as it is the means by which you not only change the contents of existing text files, but also create new text files. To copy the file you use the cp (copy) command introduced above. You also need to know the full path to the file to be copied. This is:

/users/ra/frans/public_html/2CS21/week2/timetable.txt

However, this is somewhat cumbersome, and thus Unix provides a short hand to specify the first part of the path using the ~ (tilda) character. Thus we can write:

$ cp ~frans/public_html/2CS21/week2/timetable.txt 2cs21/.

(space between timetable.txt and 2cs21). Use this "cp" command to copy the timetable.txt file into your 2CS21 directory. Remember the . (dot) character is used as a shorthand for the destination filename where we wish to keep the filenames the same. Copy the file and then change directory to your "2cs21" directory using the cd command. List the contents of the file using the more command. The file contains a skeleton timetable as shown below:

+-----------+-------+-------+-------+-------+-------+-------+-------+-------+
|           | 09:00 | 10:00 | 11:00 | 12:00 | 13:00 | 14:00 | 15:00 | 16:00 |
+===========+=======+=======+=======+=======+=======+=======+=======+=======+
|           |       |       |       |       |       |       |       |       |
| Monday    |       |       |       |       |       |       |       |       |
|           |       |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+-------+
|           |       |       |       |       |       |       |       |       |
| Tuesday   |       |       |       |       |       |       |       |       |
|           |       |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+-------+
|           |       |       |       |       |       |       |       |       |
| Wednesday |       |       |       |       |       |       |       |       |
|           |       |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+-------+
|           |       |       |       |       |       |       |       |       |
| Thursday  |       |       |       |       |       |       |       |       |
|           |       |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+-------+
|           |       |       |       |       |       |       |       |       |
| Friday    |       |       |       |       |       |       |       |       |
|           |       |       |       |       |       |       |       |       |
+-----------+-------+-------+-------+-------+-------+-------+-------+-------+

You are now going to use the ved text editor program to change the contents of this file so that it includes your own lecture times. Invoke the text editor by selecting the Editor button from the tool bar.

After the demonstration, go ahead and edit your file. Refer to the Introductory Guide to the ved Editor, or ask your tutor, for advice about using ved. If necessary complete the task in your own time. Make sure that you know how to do the following:

• Insert new text into the file
• Overwrite existing text
• Delete characters from the file
• Quit the edit (without saving any changes you have made)
• Save the edit (i.e. store the changes you have made)

These are all described in the introductory guide.

7. PRINTING

On completing the above you can print your newly-edited timetable text file using the command:

$ lpr fileName

Your tutor will show you where to collect your print out. Further information is available regrading printer and printing in the CS "Introductory Guide".

8. LOGGING OUT

At the end of the session:

1. Do not remove the timetabel text file or your "myfiles" contained in your 2CS21 directory - you will need them for your next tutorial session.
2. Close down any programs that you are running - ved, netscape (your tutor will demonstrate the latter).
3. Move the mouse until the cursor is on the grey background area of the screen (the root window).
4. Press the left button of the mouse - a menu will appear.
5. Without releasing the button, drag down until the Logout option is highlighted
6. Release the mouse button - you have now logged out.

Further information regarding logging out can be found in the "finishing a session" section of the introductory guide. Finally note that you can use the computer system at any time in any lab which is free - check the timetables outside each lab before you enter - labs are sometimes reserved for tutorial classes such as this one.

Created and maintained by Frans Coenen. Last updated 11 October 1999