Table of contents

  1. Introduction
  2. Tutorial
  3. The basics
    1. Operation modes
    2. Loading our config file
    3. Some practice
      1. Editing the file
      2. Some text manipulation
  4. A warning
  5. Useful tips and tricks
    1. Widely used ones

Introduction

Throughout the class, you will be asked to remotely login (via ssh) into a server and doing all of the labs there. Therefore, it is in your best interest to get good practice navigating your terminal and using a terminal-based text editor.

Our text editor of choice is vim, but you are free to chose nano or emacs, depending on your preferences and experience. We elected to focus on vim since you have already encountered in prior classes.

vim is already installed on most distributions. However, in case you cannot find it in your setup, you can use (assuming your are running Ubuntu or a Debian-based distribution):

  $ sudo apt install -y vim

Tutorial

In case you need a quick tutorial (you should have already done this one in CSSE132), please read through the tutorial provided by vim, it should give you all the basic concepts needed to navigate your editor.

You can launch the tutorial from your shell using:

  $ vimtutor

Please read through the tutorial then take some time to practice moving around a file in vim.

The basics

Operation modes

vim has several modes of operation, the three that are of interest to us are the following:

  1. [n]ormal mode: This is where you can navigate your text and perform some operations, such as copy and paste, delete (cut) lines or words, etc.

    vim by default starts in normal mode.

  2. [i]nsert mode: This is where you add (or insert) your text. This is pretty much the mode in which you will be doing your regular editing.

    You can enter insert mode by pressing i on your keyboard when in normal mode. This will start adding text under the current cursor.

    To exit insert mode and go back to normal mode, pressing the Escape key anywhere in your text.

  3. [c]ommand-line mode: This is where you can enter editor commands to do very useful things (like find and replace, regular expression-based operations, etc.).

    To enter command-line mode from normal mode, press the : key on your keyboard, you will notice that your cursor will move to the bottom of your screen where you can enter commands.

    Try the following commands:

    • :help Normal-mode to read the help page on normal mode.
    • :help Insert-mode to read the help page on insert mode.
    • :help Command-line-mode to read the help page on command-line mode.

    To exit the help page and go back to your main page, enter command-line mode and type :q (for quit).

Loading our config file

To make things look prettier and nicer for you, we have provided you with a sample vim configuration file that sets up some parameters and shortcuts. To get that file and place in the right spot, from your shell, do the following:

  wget -O ~/.vimrc https://www.rose-hulman.edu/class/csse/csse332/current/assets/files/vimrc

This will download our vimrc file and place it in your home directory under a hidden file (thus the . at the start). Feel free to read through that file and checkout the comments around each command, it is pretty self-explanatory.

Some practice

Let’s do some practice and write a simple C file to test our skills. From your terminal windows, open a file called example.c using

  $ vim example.c

Editing the file

You are now in normal mode, let’s enter insert mode using i. Then start typing the following code:

  #include <stdio.h>

  int x = 3;

  int main(int argc, char **argv) {
    printf("Hello world!\n");
    printf("x = %d\n", x);
  }

Okay, now we want to save our file. To do so, go into normal mode by hitting Escape. Then enter command-line mode using : and type w. This will save your buffer to the file example.c.

Our configuration file (vimrc) maps a shortcut to exit insert mode into normal mode. If you type the characters jk right after one another (in insert mode), it will act as if you pressed Escape. Try it out!

Note: If for some reason, you need jk to appear in your text, simply write the j, wait 2 seconds, then write the k, it will keep you in insert mode and the jk sequence will show up.

Some text manipulation

You can notice that in our file, the line int x = 3; shows up at line 3, but what we really wanted it to be part of the main function. Let’s make that happen.

  1. Go to line 3:

    To go to a specific line in vim, enter normal mode, then enter command-line mode using :, then type your line number followed by Enter (so your command line looks like :3). Line 3 should now be highlighted.

  2. Cut the line:

    To cut line 3 so we can move it to another spot, enter normal mode, then hit the sequence dd, you will see that the line will disappear and the text will be shifted one line higher.

    Normally, we use dd both to cut a line and deleting it (simple cut it and don’t paste it!).

    To see what you have copied/cut, you can use :reg in command-line mode.

  3. Paste the line:

    Now let’s go paste that line where we want it to be. We want int x = 3; to appear right after the int main(int argc, char **argv) { line. Therefore, in normal mode, move your cursor to line 4 (:4), then in normal mode, hit the p key. The cut line (int x = 3;) will be pasted in the line after the current one!

    If you want to paste the cut line in the line above the current one, you can use P instead of p.

  4. Fixing the indentation:

    If you notice now, the line is in the right spot, but the indentation is messed up, we don’t like that!

    To fix the indentation, here are a few methods to do so:

    • Place your cursor on the line you want to indent. Then, in normal mode, hit the == keys.
    • Place your cursor at the opening (or closing) brace (or curly brace or parenthesis) surrounding the line you want to indent (in this case, at the brace at the end/start of the main function). Then, in normal mode, hit the =% keys. This will indent the whole block of code in between the braces/parenthesis.
    • Indent the whole file. In normal mode, hit the gg=G key sequence. This will reindent the whole file but will replace your cursor at the top of the file.

    Your lines should now look better, with proper indentation!

  5. Copy instead of cut:

    To copy a line instead of cutting it, redo the same steps, except replace the dd sequence in step (2) with yy (where y stands for yank or copy).

  6. Save and exit the file:

    Now, let’s save and exit our file. We need to enter command-line mode and issue two commands: w for saving the file and q to quit the file. Fortunately, you can do both in one short by chaining them together, so you can use :wq to save the file and exit.

    You can also use :x to achieve the same purpose.

A warning

Often times, you will feel tempted to close off the terminal window without properly quitting vim. This is not a good idea as it can risk you losing your progress. To prevent that, vim often save temporary buffers that can be used to recover a file in case of an incorrect quit (you might see something like .example.c.swp show up in your directory when editing example.c).

To prevent this from messing up your submissions, please always make sure to save and quit your files before your close the terminal window. It is as simple as typing :x or :wq in command-line mode.

Useful tips and tricks

For a full cheat sheet, please take a look at the well organized document here; it is very useful when starting with vim.

Widely used ones

Here are a couple of very useful commands that I often find myself using.

  1. When entering insert mode from normal mode, you can use the following:
    • i: enter insert mode on the current cursor.
    • a: enter insert mode at the spot next to the current cursor.
    • A: enter insert mode at the end of the current line.
    • o: enter insert mode by adding a new line below the current line.

    • O: enter insert mode by adding a new line above the current line.

    • r: replace the character under the current cursor with the one pressed next.
    • R: enter replace mode. All the keys you press next will replace the characters starting from the current cursor.
  2. In normal mode:
    • l: move the cursor to the next character (equivalent to right arrow key).
    • h: move the cursor to the previous character (equivalent to left arrow key).
    • j: move the cursor to the character below the current character (equivalent to the down arrow key).
    • k: move the cursor to the character above the current character (equivalent to the up arrow key).
    • w: move to the start of the next word.
    • e: move to the end of the current word, or the end of the next if currently at the end of a word.

      ea in normal mode will move to the end of the current word and then start editing right after it!

    • u: undo the last action.
    • <C-r> : redo the last action. (<C-r> stands for holding the control key and then pressing r).
    • zz: visually move the current line to the middle of the buffer; useful if you are editing a file and reached the end of it and need to see more of it.
    • dw: cut the word under the cursor, up to and including the space character following the word.
    • de: cut the word under the cursor, up to but not including the space character following the word.
    • gg: Go to the start of the file.
    • <Shift-g> or G: Go to the end of the file.
    • $: Go to the end of the line.
    • ^: Go to the first character in the line, skipping spaces and tabs.
    • 0: Go to the first character in the line, not skipping spaces and tabs.
    • ~: Switch case for the character under the current cursor.