Espresso: A Concentrated Introduction to Java

Unix Basics

Reference: Unix Commands

Summary: In this laboratory, you will explore some of the basic Unix commands.

Contents

• Exercises
  • Exercise 0: Preparation
  • Exercise 1: Creating a Directory
  • Exercise 2: Adding Files
  • Exercise 3: Permissions
  • Exercise 4: Subdirectories
  • Exercise 5: Basics of gedit
  • Exercise 6: Aliases
• Extra Work

Exercises

Exercise 0: Preparation

Identify a partner for this lab. For today, you and your partner should sit at neighboring computers.

Exercise 1: Creating a Directory

a. Create the directory /home/username/CSC152

b. Determine which files currently exist in that directory.

Exercise 2: Adding Files

a. Make a copy of the file /home/rebelsky/Web/Espresso/Examples/afile in your CSC152 directory. You will use a form of the cp command.

b. Verify that that file is now in the directory. You will use a form of the ls command.

c. Look at the contents of your copy of that file using the full path name of the file. For example,

less /home/username/CSC152/afile

d. Change your present working directory to CSC152. You will use a form of the cd command.

e. Verify that you have changed your present working directory.

f. Look at the contents of the file using the relative path name (just afile). For example,

less afile

Exercise 3: Permissions

a. Attempt to determine what files are in your partner's CSC152 directory. What happens?

b. Attempt to read the afile file in your partner's CSC152 directory. What happens?

c. Both you and your partner should make afile readable and make the CSC152 directory executable.

d. Attempt to determine what files are in your partner's CSC152 directory. What happens?

e. Attempt to read the afile file in your partner's CSC152 directory. What happens?

f. Both you and your partner should make afile unreadable and make the CSC152 directory readable.

g. Attempt to determine what files are in your partner's CSC152 directory. What happens?

h. Attempt to read the afile file in your partner's CSC152 directory. What happens?

i. Restore permissions so that your partner can list files and can read afile.

j. Summarize (for yourself) what this exercise has taught you about permissions.

Exercise 4: Subdirectories

a. Make a subdirectory of CSC152 called yourusername. For example, a user named smith would create the directory smith. (The full name of that directory is /home/smith/CSC152/smith.)

b. Make a copy of your partner's afile in that directory.

c. Rename your original afile to bfile and move it to the new directory.

d. Make that new directory accessible to everyone.

Exercise 5: Basics of gedit

a. Start gedit.

b. Create a file that contains three lines

• Your name
• Your major and year
• Your email address

c. Save that file in your CSC152 directory under your first name. For example, Sam Smith would save it as /home/smith/CSC152/sam

d. Arrange that others in the class can access that file.

e. Obtain as many of your colleagues' info files as you can.

Exercise 6: Aliases

a. Add the following lines to the end of the file /home/username/.bashrc

alias csc152="cd /home/username/CSC152/username"
alias home="cd /home/username"

b. Save your modified .bashrc.

c. Determine what happens if you type cs152 and home. (The aliases should not work.)

d. Aliases don't take effect until you open a new terminal window. Open a new terminal window and try typing those commands again. What happens?

Extra Work

If you finish the initial work early, feel free to leave early.

History

Tuesday, 25 January 2005 [Samuel A. Rebelsky]

• Designed.

Wednesday, 26 January 2005 [Samuel A. Rebelsky]

• Created.

Tuesday, 30 August 2005 [Samuel A. Rebelsky]

• Slight edits. Added explicit versions of some commands.

Wednesday, 25 January 2006 [Samuel A. Rebelsky]

• Added more info about some commands.
• Switched emacs to gedit.
• Elimiated the extra work (all of which was based on emacs).