If you have not already done so, log into your UNIX account. You will see the greeting message and then your UNIX prompt. My prompt looks like this
[morrison@neverland morrison]$
A prompt is so-named because it is asking you to enter a command. Every UNIX command has the following anatomy
commandName -option(s) argument(s)
I will assume you have used a Mac or a DSM before; all of the familiar features of a graphics-based machine are here, you will just invoke them with a text command instead of a mouse click. We will go through some examples so you get familiar with all the parts of a UNIX command.
Let us first use the UNIX command touch. This command creates a file. At your UNIX prompt, enter
touch stuff
This creates an empty file named stuff in your account. Let us talk about the anatomy of this command. The name of the command is touch; its purpose is to create an empty file. Since you do not see a - sign, there are no options being used. The argument is stuff. This is the name of the file you created. Create a few more empty files. Enter these commands
touch foo touch bar
Now you have three files in your account. Now we will see how to list the files
Enter this command at the UNIX prompt
ls
The command ls lists your files. Notice we had neither options nor arguments. If you created the files using touch as instructed, they should appear on your screen like this
bar foo stuff
The command ls has several options. One option is the l option; it list the files in long format. To invoke it, type
ls -l
You will see a listing like this
-rw-rw-r-- 1 morrison morrison 0 Jun 9 10:50 bar -rw-rw-r-- 1 morrison morrison 0 Jun 9 10:49 foo -rw-rw-r-- 1 morrison morrison 0 Jun 9 10:49 stuff
The first column reflects the permissions for the files. The sequence
-rw-rw-r--
indicates that you and your group have read/write permission and that others ("the world") has read permission. We will discuss permissions in more detail on the directories page.
You can see your name is listed in two columns. The zero indicates the size of the file; it is empty. Then there is a date, a time and the file name. This is the long format for file listing; it is seen by using the -l option in the ls command.
Another option is the -a option. This lists all files, including "hidden" files. Hidden files have a dot (.) preceding their name. To see them, enter
ls -a
at the UNIX command line. You will see the files you saw using ls and several hidden files with mysterious names like .bash_profile. Do not delete these; they provide the configuration for your account. You can use more than one option at once. For example, entering
ls -al
shows all of your files and hidden files in long format. Try this now.
Now we will show how to display a file to the screen. Let us look inside your .bash_profile file. Enter the command
cat .bash_profile
The command name is cat, short for catalog (the file to the screen). We are using no options, but the filename is an argument to cat. If a file is long and you want to see it one screenful at a time, use the command more. The command more takes a filename as an argument and shows it one screenful at a time. You can hit the spacebar to see the next screenful or hit the enter key to scroll down one line at a time. To exit more at any time, type a q and more quits.
Copying, Renaming and Deleting Files Three commands every beginner should know are: cp, rm and mv. These are, respectively, copy, remove and move(rename). Here are their usages
cp <oldFile> <newFile> rm <garbageFile> mv <oldFile> <newFile>
The first command copies oldFile to newFile. If newFile does not exist, it creates newFile; otherwise it will overwrite newFile.
Try this at your unix prompt: cp .bash_profile quack
Notice that the command cp has two arguments: the source file and the recipient file. If you executed the last command successfully, you make a copy of your .bash_profile file to a file called quack.
Now enter ls -l
You will see that quack's size is nonzero because it has a copy of the contents of your .bash_profile file in it. Mine has size 191.
-rw-rw-r-- 1 morrison morrison 0 Jun 9 10:50 bar -rw-rw-r-- 1 morrison morrison 0 Jun 9 10:49 foo -rw-r--r-- 1 morrison morrison 191 Jun 9 11:25 quack -rw-rw-r-- 1 morrison morrison 0 Jun 9 10:49 stuff
Let us now remove the file stuff. We are going to use an option, however. Enter this: rm -i stuff. This command has an option (see the - sign??) and the argument stuff. The system will then ask you if you are sure you want to remove the file. Tell it yes by typing the letter y. The -i option is also available with cp. I recommend you use it to avoid costly mistakes.
Finally, we shall use mv This "moves" a file to have a new name. Let's change the name of quack to honk and back again. To change quack to honk, enter mv quack honk. Once you do this, list the files in long format. Then change it back.
Now you know how to copy, move, and create files. You can show them to the screen and you can list all the files you have. So far, we can create files two ways, we can create an empty file with touch or copy an existing file to a new file with cp
Next you will want to know how to edit files.
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