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.

We will also soon be working with Git and GitHub. These will also require us to use plain text. More on that in a couple of chapters.

nano

The nano text editor is one of the user-friendliest of the text editors available on the Linux command line, but it still requires some adjustment 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.

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.

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. We will use nano to edit configuration files and publish text to GitHub.