Mac OS X Leopard - ARCAism

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CHAPTER 18 INTRODUCING DARWIN AND THE SHELL
Editing Files
Editing files in Darwin is just one of those things that you’ll eventually have to do to get the most
out of it. For the most part, using a normal Mac OS X text editor like TextMate (€39), BBEdit
($125), TextWrangler (free), or Smultron (free, donations accepted) may be your best bet—
however, at times it may be handy or necessary to edit a file on the command line. Leopard ships
with four command line–based text editors in Darwin: Ed, Vim, Emacs, and Nano. Ed is the
original text editor for UNIX, but it has been surpassed in both usability and features by many
newer text editors. Despite this, it is still included in most UNIX distributions since it has found
a small niche within certain shell scripts. Each of the remaining three has its advantages, and
what it comes down to for most people is a matter of taste and habit (i.e., once you start using
one it becomes a bit frustrating to use another, since they vary quite a bit).
Vim
NOTE Since we mentioned some GUI text editors previously, it’s worth noting that many of
these come with a command-line executable as well, so that you may open any file in them
from the command line. Specifically, BBEdit allows you to install the bbedit command-line executable,
and TextMate allows you to install the tm command-line executable. Each of these will
open the file in the GUI application, but it makes it handy to do so from the command line.
Also . . . obviously these won’t help you much if you are accessing the machine remotely
through a terminal window.
Vim is, as the name suggests, an “improved” clone of Vi (Visual Editor), which in turn is based on
Ex, which is based on the aforementioned Ed (which was based on an even older text editor
called QED). Vim is interesting to people new to command-line editors in that, like its predecessors,
it is a dual-mode text editor. To get things done, you must switch between an insert or edit
mode and a command mode. While this way of working with a text editor takes some getting
used to, it’s fairly easy once you get the knack of it. Also, Vim, Vi, or one of its clones is installed
by default on almost every version of UNIX or Linux, so once you learn it, you can count on
something like it to be installed on any UNIX (or UNIX-like) system you encounter.
NOTE Vim specifically has a special third mode—visual mode—which can be toggled by
typing v in command mode. Once in visual mode, you can move the cursor around normally—
however, the text you move over will be selected. This mode is very handy for selecting text
for precise copying and pasting.
When you launch Vim, you can either open an existing file, create a new file, or just jump
into the editor without creating a file. The syntax is fairly straightforward:
vim [filename]
where filename is either an existing file or one you wish to create.
NOTE In Darwin, vi, view, vimdiff, and ex all point to vim—however, they each cause Vim to
exhibit different default behavior. vi and vim will both launch in normal mode, view will open a
file read-only, vimdiff allows you to open multiple files at the same time so that you can compare
them, and ex will open Vim in ex mode (the :vi command will return you to normal mode).
Vim will begin in command mode when opening a new or existing file; so, if we open the
soliloquy file we’ve been working with earlier in the chapter, we will be presented with the
following: