Basic Unix Tutorial

So in consideration for some new and/or transfer students who may not be entirely familiar with UNIX, I created this brief tutorial with some common commands as well as some concepts that will help you get along.

If you have any other questions, you can send me an email at:

wreasor@ucsd.edu

Common Commands / Quick Ref

Command	Description	Example Usage
ls	Prints to contents of the current directory	mylogin% ls
pwd	Shows the current directory	mylogin% pwd
cp < arg1, arg2 >	Copy file in arg1 to path in arg2	mylogin% foo.java ../foo2.java
rm < file to remove >	Removes the specified file	mylogin% rm ../projects/spam.txt
mkdir	Creates a directory to store data .. Same as a 'folder' in Windows	mylogin% mkdir mystuff
cd < path >	Changes working directory to specified path	mylogin% cd ../../morestuff

Working with your account

Now we are going to apply some of the commands listed above. For this, let's refer to the diagram below which is a sample representation of the file structure in a random account.

                    
                      -------HOME-------         		   
                     /                  \
	          mystuff           assignments--------
                    |                |                 \
                  foo.txt          ni.java              P0
	          ni.class                               |
                                                      P0.java
                                                      P0.class

Or a heirarchial view of the visual representation above is:

               HOME
	        |---- mystuff
		|       |---- foo.txt
                |
                |---- assignments
                        |---- ni.java
			|     ni.class
                        |
                        |---- P0
                              |---- P0.java
                                    P0.class

Ok, so we are going to start in the 'HOME' directory, and we want to go straight to the P0 directory to do some work there. We would use the following command. Note that the actual command is in bold:

mylogin% cd assignments/P0

Now, if we type in pwd, we will see that we are indeed in the P0 directory. It is important to note the following when working with directories in UNIX:

Spaces matter. Saying cd assignments/P0 is NOT the same as saying cd assignments/ P0
Capitalization matters. Saying cd assignments/P0 is NOT the same as saying cd assignments/p0

Now we are in the 'P0' directory. Well, we decided that we no longer need the 'P0.class' file, so let's remove it. We would use the following command:

mylogin% rm P0.class

It's gone now, and our structure looks like this.

                    
                      -------HOME-------         		   
                     /                  \
	          mystuff           assignments--------
                    |                |                 \
                  foo.txt          ni.java              P0
	          ni.class                               |
                                                      P0.java

Let's make a backup copy of P0.java and put it in the mystuff directory. Here, I will introduce the ~ shortcut, which refers to your designated home directory, in this case, it is 'HOME'.

Method 1:
mylogin% cp P0.java ../../mystuff/P0.java

Method 2:
mylogin% cp P0.java ~/mystuff/P0.java

More important notes on working with directories:

. refers to the current directory.
.. refers to the parent directory.
~ refers to your designated home directory.

Whatever method we use, we now made a backup copy of P0.java, and put it in the 'mystuff' directory, so that the stucture is now as follows:

                    
                      -------HOME-------         		   
                     /                  \
	          mystuff           assignments--------
                    |                |                 \
                  foo.txt          ni.java              P0
	          ni.class                               |
                  P0.java                             P0.java

Well, we made a backup copy of P0.java and put it in mystuff. Now, we want to make another copy of P0.java to be placed in the P0 directory, change the name of it to P1.java, and then delete the original P0.java that is there. This is what we would do, from the P0 directory:

mylogin% cp P0.java ./P1.java
mylogin% rm P1.java

Notice how for arg2 in the cp command, you can give it whatever name you want. Anyways, here is our structure:

                    
                      -------HOME-------         		   
                     /                  \
	          mystuff           assignments--------
                    |                |                 \
                  foo.txt          ni.java              P0
	          ni.class                               |
                  P0.java                             P1.java

That should get you going on UNIX enough where you can at least perform basic operations needed. Feel free to learn more about this, as it can only help you in the long run.