Unit 12: Getting Started with vim

Setting Up Your vim Environment

Like many other Unix programs, you can configure your preferences by creating an rc (run commands) file in your home directory. These rc files will be read by the corresponding programs and executed line-by-line as if the text is entered into the program through a keyboard. You can view these rc as a script that will be executed automatically whenever a program starts.

For vim, the rc file is called .vimrc. The . in the front of the file name carries a special meaning in Unix. It means that this file is hidden -- you won't see it when you ls. Hiding the run command files prevent your home directory from being cluttered. To tell ls to show the hidden files, use the -a flag 

$ ls -a

We have created a .vimrc file, with reasonable defaults, for your use. Note that different modules may choose to use a different coding convention and so a different setting. But this .vimrc file suffices for now.

To get this file, 

$ cd
$ mv .vimrc .vimrc.bak
$ mkdir .backup
$ wget https://raw.githubusercontent.com/nus-unix-workshop/2021-s1/master/.vimrc

The first line changes your working directory to your home. The second line creates a backup .vimrc, if one exists. If it does not, mv will give you an error, which is fine. The third line creates a hidden backup directory for vim. The last line downloads our .vimrc into your home directory.

Our default .vimrc set up vim such that it creates a backup copy of the file you are editing every time and store it in ~/.backup. This feature has saved me from pulling my hair out countless times. It is highly recommended that you set this up whenever you vim.

Lesson 1: Navigation

Now, you can stay in your home directory or go back to your workshop directory.

Download the following file for practice using vim in this session. 

$ wget https://raw.githubusercontent.com/nus-unix-workshop/2021-s1/master/jfk.txt

The file named jfk.txt should be downloaded. Now let's start your first vim session.

$ vim jfk.txt

When you start, you will be in NORMAL mode. For now, just move around the cursor with H J K L. Get comfortable with using the keys.

Next, try ( and ) to move forward and backward, sentence-by-sentence.

Next, try { and } to move forward and backward, paragraph-by-paragraph.

Use 0 to jump to the beginning of the line, and $ to jump to the end of the line.

Use G+G to jump to the beginning of the file, and Shift+G (G) to jump to the last line of the file.

Now try /, type in any word (or prefix of a word) and Enter. This should move the cursor to the beginning of the word. You can use N and Shift+N to move to the next match and the previous match.

When you are comfortable with moving around, you can Shift+Z+Z to exit.

Congratulations, you have just completed your first session in vim!

Lesson 2: Manipulating Text

Now, we are going to open up the same file again and try to manipulate the text. We are going to stay in the NORMAL mode still.

$ vim jfk.txt

Deletion

Try 0 D 3 W to move the cursor to the beginning of the line and delete three words.

Press U to undo. This is another lifesaver that you should remember.

In vim, repeating the same command twice usually means applying it to the whole line. So D D deletes the current line. Try that.

Pairing a command with Shift (or the capital letter version) usually means applying the action until the end of the line. So Shift+D deletes from the current cursor until the end of the line.

Copy Pasting

Hit P to paste back what you just deleted. Try moving the cursor to somewhere else and paste.

To copy (or yank) the current line, hit Y Y.

Remember that all these commands can be composed using the movement-action-movement pattern. For instance, Shift+9 Y Shift+0, which corresponds to: move to the beginning of the sentence, yank, and until the end of the sentence, basically copy the current sentence.

As you have seen in the D 2 W example, you can preceed an action with a number to repeat an action multiple times.

Try Y Y 9 P. You should be able to understand what just happened!

Deleting a Character

The X command deletes the current character.

Try this exercise: At the end of the file jfk.txt, there are some typos: 

libertyi. liberty.
Change libertyi. liberty. to libtery. by positioning the cursor on the second i and delete it. Then use Shift+D to delete the extra liberty. at the end of the sentence.

Visual Mode

In addition to the INSERT and NORMAL modes, vim has the third mode, the VISUAL mode. You can enter the VISUAL mode by hitting V. Once in visual mode, you can move your cursor to select the text and perform some actions on it (e.g., D or X to delete, Y to yank).

Hitting Shift+V will allow you to select line-by-line.

The VISUAL mode allows us to pipe the selected text to another Unix command, and replace it with the result of that command.

Go ahead and try to select a paragraph in jfk.txt, and hit :. You will see that 

:'<,'>
appears in the last line of the terminal. At this point, you can type in actions that you want to perform on the selected text. For instance, 
:'<,'>w john.txt
will write it to a file named john.txt.

But, let's try the following: 

:'<,'>!fmt

!fmt tells vim to invoke the shell and run fmt. fmt is another simple small Unix utility that takes in a text (from standard input) and spew out formatted text in the standard output. You will see that the width of the text has changed to the default of 65.

You can try something that we have seen before. Reselect the text, and hit 

:'<,'>!wc
The selected text will be replaced with the output from wc.

The : command

You have seen examples of : commands for writing to a file or piping selected text to an external command.

The : command also opens up a large number of actions you can do in vim. Here are a few essential yet simple commands.

Other advanced features such as search-and-replace, changing preferences, splitting windows, opening new tabs, are also accessible from the : command.

The : command prompt supports Ctrl+P and Ctrl+N for navigating back and forth your command history, just like bash. It also supports Tab for auto-completion.

Lesson 3: Insert mode!

Finally, we are going to try inserting some text. Remember, to use INSERT mode, we always start with a command I A O or S (may paired with Shift) followed by the text that you want to insert, followed by Esc.

Let's try I (insert). Place your cursor anywhere, hit I, and start typing, when you are done. Hit Esc.

You just added some text to the file.

Place your cursor anywhere, hit A (append), and start typing, when you are done. Hit Esc. A appends the text to the end of the current line.

Hit O (open) and start typing, when you are done. Hit Esc. O opens up a new line for the your text.

Hit S (substitute) and start typing, when you are done. Hit Esc. S substitute the current character with your text.

Now try it with Shift and see the difference in behavior.

Learning More

There is only so much we can cover in 30 minutes. This workshop only covers the tip of the iceberg. To learn more about vim, we suggest that you run vimtutor on the command line and follow through the tutorials.

Once you are comfortable, you can soup up your vim with various plugins and learn how to use advanced commands (such as search and replace, jumping between files, recording macros, folding, auto-completion) that are invaluable for programming.

There are also many video tutorials and resources online. Some interesting ones are: