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.