Text editors

As we learn more about how to work on the command line, we will acquire the need to write in plain text or edit configuration files. Most configuration files for Linux applications exist in the /etc directory and are regular text files. For example, later in the semester we will install the Apache Web Server, and we will need to edit Apache's configuration files in the process.

In order to edit and save text files, like the Apache configuration files, we need a text editor. Programmers use text editors to write programs, but because programmers often work in graphical user environments, they may often use graphical text editors or graphical Integrated Development Environments (IDEs). It might be that if you work in systems librarianship, that you will often use a graphical text editor, but knowing something about how to use command line-based editors can be helpful. For a variety of reasons, a GUI text editor or IDE isn't always available.

What is a Plain Text?

Plain text is the most basic way to store human-readable textual information. Whenever we use a word processor program, like Microsoft Office, we are creating a complex series of files that instruct the Office application how to display the contents of the file as well as how the contents are formatted and arranged. This can easily be illustrated by using an archive manager to extract the contents of a .docx file. Upon examination, most of the files in a single .docx file are plain text that are marked up in XML. The files are packaged as a .docx file and then rendered by an application, commonly Microsoft Word, but any application that can read .docx files will do.

A plain text file only contains plain text. Its only arrangement is from top to bottom. It does not allow for any kind of additional formatting, and it does not include media. It is the closest thing the digital has to output produced by a typewriter, but a typewriter that's connected to the internet.

A lot of content is written in plain text. For example, HTML is written in plain text and the web browser uses the HTML markup to render how a page will look.

<p>This is using a HTML paragraph tag.
The web browser would render this like the other paragraphs on this page.
However, it's written in a code block,
which allows me to display the HTML as source code.</p>

The rendered result is not plain text but HTML, just like the rendered result of all those XML files in a .docx file are not plain text but a .docx file. Software is written in plain text files because programming languages cannot evaluate content that is not just text. Those of you who have learned how to use the R programming language wrote your R code in plain text likely using the RStudio IDE. For our purposes, we need plain text files to modify configuration files for the various programs that we will install later.

Why Edit in Plain Text

Most of the time when we configure software, we might use our mouse to find the settings menu in an application that we are using. Then we'll make a change in those settings. For the most part, all we're really doing is making a change in some text file somewhere. The application's GUI-ness simply obscures that process.

We have to be more direct when we are working on the command line. That is, the setting configurations we will do require editing plain text files that modify how the programs will use work. Often the settings for programs can only be modified by editing their plain text configuration files.

nano

The most common text editor on many Linux systems is nano. The nano text editor is a user-friendly command line text editor, but it requires some learning as a new command line user. The friendliest thing about nano is that it is modeless. You are already accustomed to using modeless editors. It means that nano can be used to enter and manipulate text without modes, like insert mode or command mode. It is also friendly because, like many graphical text editors and software, it uses control keys to perform its operations.

A modal text editor has modes such as insert mode or command mode. In insert mode, the user types text as anyone would in any kind of editor or word processor. The user switches to command mode to perform operations on the text, such as find and replace, saving, and cutting and pasting. Switching between modes usually involves pressing specific keys. In Vim and ed(1), my text editors of choice, users start in command mode and switch to insert mode by pressing the letter i or the letter a. The user returns to command mode by pressing the Esc key in Vim or by pressing the period in a new line in ed(1).

The tricky part to learning nano is that the control keys are assigned to different keystroke combinations than what many graphical editors (or word processors) use by convention today. For example, instead of Ctrl-c or Cmd-c to copy text, in nano you press the M-6 key (press Alt, Cmd, or Esc key and 6) to copy. To paste, press Ctrl-u instead of the more common Ctrl-v. Fortunately, nano lists the shortcuts at the bottom of the screen.

nano is a text-editor with old origins. Specifically, it's a fork of the Unix pico editor. The keyboard shortcuts used by nano were carried over from the pico editor. These keyboard shortcuts were designed before the Common User Access guidelines helped standardize the common keyboard shortcuts we use today for opening, saving, closing, etc files.

The shortcuts listed need some explanation. The carat mark is shorthand for the keyboard's Control (Ctrl) key. Therefore to perform the Save As operation on a file, we write out the file by pressing Ctrl-o (although Ctrl-s will work these days, too). The M- key is important. Depending on your keyboard configuration, it may correspond to your Alt, Cmd, or Esc keys. To search for text, you press ^W or Ctrl and W; that is, Ctrl-W (lowercase w will work). If your goal is to copy, then press M-6 to copy a line. Move to where you want to paste the text, and press Ctrl-U to paste.

We start nano simply by typing nano on the command line. This will open a new, unsaved file with no content. Alternatively, we can start nano by specifying a file name after typing nano. For example, if I want to open a file called example.txt, then I type the following command:

nano example.txt

If the file doesn't exist, this will create it. If it does exit, then the command will open it.

One of the other tricky things about nano is that the menu bar (really just a crib sheet, so to speak) is at the bottom of the screen instead of at the top, which is where we are mostly accustomed to finding it these days. Also, the nano program does not provide pop up dialog boxes. Instead, all messages from nano, like what to name a file when we save it, appear at the bottom of the screen.

Lastly, nano also uses distinct terminology for some of its functions. The most important function to remember is the Write Out function, which means to save.

For the purposes of this class, that's all you really need to know about nano. Use it and get comfortable writing in it. Some quick tips:

  1. nano file.txt will open and display the file named file.txt.
  2. nano by itself will open to an empty page.
  3. Save a file by pressing Ctrl-o.
  4. Quit and save by pressing Ctrl-x.
  5. Be sure to follow the prompts at the bottom of the screen.

Other Editors

It's good to be familiar with nano because it's often the default text editor on Linux operating systems nowadays. However, if you are interested in using a command line text editor with familiar keyboard shortcuts, then there are others you may want to try. Specifically, I suggest you investigate the tilde and the micro text editors. Both of these are really quite nice.

tilde

The tilde text editor is a user friendly text editor that uses conventional keybindings (like ctrl-s for saving, etc). tilde also offers a standard menu bar, which you activate by pressing the Alt key and the letter for the menu option. For example, to open the File menu, press Alt-F. Press the Esc key to exit the menu.

You can install tilde via the apt command:

sudo apt install tilde

You can run tilde either by itself or by invoking a pre-existing or new file:

tilde

Or:

tilde newfile.md

micro

The micro text editor is another user friendly editor. Like tilde, it uses conventional key bindings. Unlike tilde, there is no menu bar, but you can press ctrl-g to open a help menu. With the help menu open, use your arrow keys to read through the documentation and learn more about its capabilities and its functions. One of the nice things about micro is that you can open multiple files in tabs. Press ctrl-q to exit the help menu.

You can install it via the apt command and start the program like you can with the other editors:

sudo apt install micro

Editing .bashrc

By default, your Bash shell is probably white text on a black background. We can add some color to this by modifying our Bash shell configuration file. To do so, open the .bashrc file with nano or your text editor of choice, like tilde or micro:

nano ~/.bashrc

Scroll to the end of the file and add these two lines:

LS_COLORS='rs=0:di=04;31:fi=00;00:ex=01;93';
export LS_COLORS

Next, go to the line that starts with the text below, which is probably line 46:

# force_color_prompt=yes

Remove the comment character (i.e., the pound sign, #) at the beginning of the line. The result should be:

force_color_prompt=yes

Save the file and exit nano, and then at the shell prompt, type the following command:

source ~/.bashrc

LS_COLORS Note

Although the above modification will enable color in our terminals, we don't have to settle for the defaults. To change the colors when listing files and directories, we modify the LS_COLORS variable. The LS_COLORS setting is a bit complicated. It contains several parameters separated by colons. Let's break it down:

LS_COLORS='rs=0:di=04;31:fi=00;00:ex=01;93';
  • LS_COLORS: A Bash environmental variable that holds the color values for the ls command.
  • rs=0: This starting parameter resets text formatting to normal (non-bold, default colors, etc). It's placed at the beginning to ensure that we start from basic values.
  • di=04;31: This sets the color of directory names (di) to be underlined (04) and red (31). If you'd rather directory names formatted in bold rather than underlined, you can change 04 to 01. If you'd rather directory names to be green rather than red, you can change 31 to 32. See other formatting properties here: Configuring LS_COLORS.
  • fi=00;00: This sets the color of regular files. Because both values are zero (00;00), the ls command lists these with no special color or style.
  • ex=01;93: This set the color of executable files (i.e., programs) to be bold (01) and bright yellow (93).

Feel free to play with the colors of the ls command. Remember to run source ~/.bashrc to put the changes into effect.

A note about other text editors: ed, Vi/Vim, Emacs

The traditional Unix and Linux text editors are ed, vim, and emacs. I first started using Linux because I found emacs, but sometime during my early Linux years, I switched to vim. Vim is a descendant of the vi text editor, which itself is a descendant of the ed editor. ed was used to write the first versions of the Unix operating system over 50 years ago when teletypes machines (and not video monitors) were the common input/output devices. It's still available, and I use it often. vi was an extension of ed and was written to take advantage of computer monitors. vim (or Vi Improved) added enhancements to vi and is my main editor. emacs is highly extensible text editor that can do about anything. It's so versatile, the saying goes that emacs is an "operating system posing as a text editor."

These editors are extremely powerful once you learn them. Even though they are quite popular, they are not user-friendly. (ed probably isn't all that popular, but it has a dedicated following.) If interested, there are plenty of online resources that provide tutorials on getting started with these text editors. I won't teach you how to use them because it would take too much time, but they are worth knowing about because all three are important parts of Unix and Linux history.

Conclusion

In the prior lesson, we learned how to use the Bash interactive shell. We will continue to do that, but in the meantime, we begin to learn how to use a command line text editor. These include nano, tilde, and micro. We will use a text editor to edit configuration files and publish text to GitHub. It's your choice what you want to use.

Appendix: My .nanorc

You can configure the look and feel of tilde and micro through their menus or help options. You can configure nano to look and behave in certain ways, too. If you decide to use nano and want to mimic the setup I have, then create a file called .nanorc in your home directory:

nano ~/.nanorc

And add the following to the file:

# Syntax:
# set element fgcolor,bgcolor
set titlecolor red,black
set statuscolor blue,white
set errorcolor white,red
set selectedcolor white,black

set numbercolor lightblue
set stripecolor red
set keycolor black,white
set functioncolor white,black 

set speller "aspell -x -c"

## When soft line wrapping is enabled, make it wrap lines at blanks
## (tabs and spaces) instead of always at the edge of the screen.
set atblanks

## Use auto-indentation.
set autoindent

## Back up files to the current filename plus a tilde.
# set backup

## The directory to put unique backup files in.
# set backupdir "~/.backup"

## Use bold text instead of reverse video text.
set boldtext

## Remember the used search/replace strings for the next session.
set historylog

## Display line numbers to the left of the text.
set linenumbers

## Enable vim-style lock-files.  This is just to let a vim user know you
## are editing a file [s]he is trying to edit and vice versa.  There are
## no plans to implement vim-style undo state in these files.
set locking

## Remember the cursor position in each file for the next editing session.
set positionlog

## Do extended regular expression searches by default.
set regexp

## Allow nano to be suspended.
set suspend

## Use this tab size instead of the default; it must be greater than 0.
set tabsize 8

## Convert typed tabs to spaces.
set tabstospaces

You can read about how to make such settings in the man page for the nano configuration file:

man nanorc