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, 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.

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 normally render this like
the other paragraphs on this page.
However, it's written in a code block,
which allows us to display the HTML tags
and appear as if it's real 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. Softare 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 do it, for example, by using our mouse to find the settings menu in some application that we are using. All that does, for the most part, is make changes to some text file somewhere. We will have to be more direct since we are working on the command line only. That is, the kind of settings configurations we will do will require editing a variety of plain text files that the programs will use to modify how they work. Often the settings for programs can only be modified by editing their plain text configuration files.

nano

The nano text editor is a fairly 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, which is what you're already accustomed to using. This means nano can be used to enter and manipulate text without changing to insert 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, cutting and pasting but cannot insert text as they would in insert mode. Switching between modes usually involves pressing some specific keys. In Vim and ed(1), my text editors of choice, the user starts in command mode and switches to insert mode by pressing the letter i or the letter a. The user may switch back 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. Then to paste, you 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, though. The carat mark is shorthand for the keyboard's Control (Ctrl) key. Therefore to Save As a file, we write out the file by pressing Ctrl-o (although Ctrl-s will work, too). The M- key is also important, and depending on your keyboard configuration, it may correspond to your Alt, Cmd, or Esc keys. To search for text, you press ^W, 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 can 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 above 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 important to be familiar with nano because it's generally 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. In the meantime, here are a couple of more friendly editors to test out.

tilde

The tilde text editor is a user friendly text editor that uses conventional keybindings (like ctrl-s for saving, etc).

You can install it via the apt command:

sudo apt install tilde

micro

The micro text editor is also user friendly, and, like tilde, uses conventional key bindings. Press ctrl-g to enter its help menu. Use your arrow keys to read through it and learn more about its capabilities and its functions. Press ctrl-q to exit the help menu.

You can install it via the apt command:

sudo apt install micro

ed(1), Vi/Vim, Emacs

ed(1), Vi/Vim, and Emacs are the traditional Unix and Linux text editors. I first started using Linux because I found emacs, but sometime during my early Linux years, I switched to vim, which is a descendent of the vi text editor, which itself is a descendent of the ed editor. None of these editors are user-friendly, but they are extremely powerful once you learn them, and they are still quite popular (well, ed probably isn't all that popular). There are plenty of online resources that provide tutorials on getting started with these text editors. I won't teach how to use them because it will 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, in this lesson, we begin to learn how to use a command line text editor, nano. I also introduce you to friendlier editors (tilde and micro) that you might prefer over nano. We will use a text editor to edit configuration files and publish text to GitHub. It's your choice what you want to use.

My .nanorc

You can configure nano to look and behave in certain ways. If you want to mimic the setup I have, then create a file called .nanorc in your home directory, and add the following to it:

# set element fgcolor,bgcolor
set titlecolor brightwhite,blue
set statuscolor brightwhite,green
# set errorcolor brightwhite,red
set selectedcolor brightwhite,magenta
# set stripecolor ,yellow
set numbercolor cyan
set keycolor cyan
set functioncolor green

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