Working with Text Files

Debian GNU/Linux: Guide to Installation and Usage" by John Goerzen and Ossama Othman is part of the HackerNoon Books Series. You can jump to any chapter in this book here. Working with Text Files

8. Working with Text Files

Text files are prevelant on a GNU/Linux system. They hold everything from documentation to configuration files. Fortunately, it’s easy to work with them.

8.1 Viewing Text Files

A text file is simply a normal file that happens to contain human-readable text. There’s nothing special about it otherwise. The other kind of file, a binary file, is meant to be interpreted by the computer.

You can view either kind of file with the less file pager if you have it installed (install it if you haven’t, it’s quite useful). Type less /etc/profile to view a sample text file. Notice that you can read the characters even if their meaning is obscure. Type less /bin/ls to view a binary file. As you can see, the ls program is not meant to be read by humans.

Sometimes, you’ll find files that end with .gz. These files may be viewed with zless; you can run it like so:

zless /usr/doc/ae/changelog.Debian.gz

Tip: zless is great for viewing documentation, which is often shipped in .gz form.

The difference between the two kinds of files is purely a matter of what they contain, unlike in some other systems (such as DOS and MacOS), which actually treat the files differently.

Text files can contain shell scripts, documentation, copyright notices, or any other human-readable text.

Incidentally, this illustrates the difference between source code and binary executables. /bin/ls is a binary executable you can download from Debian, but you can also download a text file that tells the computer how to create /bin/ls. This text file is the source code. Comparing /bin/ls to /etc/profile illustrates how important source code is if someone wants to understand and modify a piece of software. Free software provides you or your consultants with this all-important source code.

8.2 Text Editors

A text editor is a program used to create and change the contents of text files. Most operating systems have a text editor: DOS has edit, Windows has Notepad, MacOS has SimpleText.

Debian provides a large variety of text editors. vi and Emacs are the classic two, which are probably both the most powerful and the most widely used. Both vi and Emacs are quite complex and require some practice, but they can make editing text extremely efficient. Emacs runs both in a terminal and under the X Window system; vi normally runs in a terminal but the vim variant has a -g option that allows it to work with X. text editors

Simpler editors include nedit, ae, jed, and xcoral. nedit and xcoral provide easy-to-use X Window system graphical interfaces. There are also several vi variants. Additionally, you can find and a GNU Emacs variant called XEmacs.

This book does not cover the use of any particular editor in detail, though we will briefly introduce ae since it is small, fast, and can be found even on the Debian rescue disks, so it pays to know a bit about it for usage in a pinch. When you need to do more serious editing, check out vim or GNU Emacs. Emacs provides an excellent interactive tutorial of its own; to read it, load Emacs with the emacs command and type F1 t. Emacs is an excellent choice for new users interested in a general-purpose or programming editor.

8.3 Using ae

You can start ae by giving it the name of a file to edit, like so:

$ ae filename.txt

This will bring up an editor screen. The top part of this screen provides some quick help; the bottom shows the file you’re editing. Moving around in this editor is simple; just use the arrow keys. You can save the file by pressing C-x C-s and then exit the editor by pressing C-x C-c. Once you feel comfortable with the editor, you can press C-x C-h to turn off the help. That’s it! Knowing this will let you do basic editing. For programming or more detailed editing work, you’ll want to investigate other editors as discussed earlier.

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