Kate is the KDE Advanced Text Editor, and it does a great job for editing any type of text files, like Bash or Perl scripts, or C/C++ sources.
Kate is really the most complete GUI (Graphical User Interface) text editor I've ever tried. Some of the basic features it has (and practically any good text editor intended for programmers should have) are: good highlighting for various programming languages (it offers default syntax highlighting for an amazing number of source files, like Bash, Perl, C, Lisp, Python, and even Quake scripts are supported), the block selection mode, which allows you to select text based on columns instead of selecting whole lines, indentation which works good enough, export to HTML and even a spell checker.
Kate can be successfully used for both taking notes, editing configuration files, or creating small projects like a C application or a command line tool.
Kate allows you to save sessions and to work with several files at a time. For example, you can split the view vertically or horizontally, work to a file in one view and another one in the second view. Changes will be visible to both files if they are the same. It also provides an embedded terminal, which can use Konsole's default settings. The terminal is very helpful if you work at a source file and then you want to compile without opening another shell application.
It has a very fast load time, very stable and benefits of a complete configuration options via the Settings -> Configure Kate... menu option.
Kate definitely deserves its name, of an advanced text editor. It offers practically anything you can ask from a text editor, and even more.
Updated: April 2, 2009