1: # Editing
3: ## Introducing vi
5: It is not like the vi editor needs introducing to seasoned UNIX users. The vi
6: editor, originally developed by Bill Joy of Sun Microsystems, is an endlessly
7: extensible, easy to use *light* ASCII editor and the bane of the newbie
8: existence. This section will introduce the vi editor to the newbie and perhaps
9: toss in a few ideas for the seasoned user as well.
11: The first half of this section will overview editing, saving, yanking/putting
12: and navigating a file within a vi session. The second half will be a step by
13: step sample vi session to help get started.
15: This is intended as a primer for using the vi editor, it is *not by any means* a
16: thorough guide. It is meant to get the first time user up and using vi with
17: enough skills to make changes to and create files.
19: ### The vi interface
21: Using the vi editor really is not much different than any other terminal based
22: software with one exception, it does not use a tab type (or curses if you will)
23: style interface, although many versions of vi *do use* curses it does not give
24: the same look and feel of the typical curses based interface. Instead it works
25: in two modes, *command* and *edit*. While this may seem strange, it is not much
26: different than windows based editing if you think about it. Take this as an
27: example, if you are using say gedit and you take the mouse, highlight some text,
28: select cut and then paste, the whole time you are using the mouse you are not
29: editing (even though you can). In vi, the same action is done by simply deleting
30: the whole line with `dd` in command mode, moving to the line you wish to place
31: it below and hitting `p` in command mode. One could almost say the analogy is
32: *mouse mode vs. command mode* (although they are not exactly identical,
33: conceptually the idea is similar).
35: To start up a vi session, one simply begins the way they might with any terminal
36: based software:
38: $ vi filename
40: One important note to remember here is that when a file is edited, it is loaded
41: into a memory buffer. The rest of the text will make reference to the buffer and
42: file in their proper context. A file *only* changes when the user has committed
43: changes with one of the write commands.
45: ### Switching to Edit Mode
47: The vi editor sports a range of options one can provide at start up, for the
48: time being we will just look at the default startup. When invoked as shown
49: above, the editors default startup mode is command mode, so in essence you
50: cannot commence to typing into the buffer. Instead you must switch out out of
51: command mode to enter text. The following text describes edit start modes:
53: * `a` -- Append after cursor.
54: * `A` -- Append to end of line.
55: * `C` -- Change the rest of current line.
56: * `cw` -- Change the current word.
57: * `i` -- Insert before cursor.
58: * `I` -- Insert before first non blank line.
59: * `o` -- Open a line below for insert.
60: * `O` -- Open a line above for insert.
62: ### Switching Modes & Saving Buffers to Files
64: Of course knowing the edit commands does not do much good if you can't switch
65: back to command mode and save a file, to switch back simply hit the `ESC` key.
66: To enter certain commands, the colon must be used. Write commands are one such
67: set of commands. To do this, simply enter `:`.
69: Hitting the colon then will put the user at the colon (or *command* if you will)
70: prompt at the bottom left corner of the screen. Now let us look at the save
73: * `:w` -- Write the buffer to file.
74: * `:wq` -- Write the buffer to file and quit.
76: ### Yanking and Putting
78: What good is an editor if you cannot manipulate blocks of text? Of course vi
79: supports this feature as well and as with most of the vi commands it somewhat
80: intuitive. To yank a line but *not* delete it, simply enter `yy` or `Y` in
81: command mode and the current line will be copied into a buffer. To put the line
82: somewhere, navigate to the line above where the line is to be put and hit the
83: `p` key for the *put* command. To move a line, simply delete the whole line
84: with the `dd` command, navigate and put.
86: #### Oops I Did Not Mean to do that!
88: Undo is pretty simple, `u` undoes the last action and `U` undoes the last line
89: deleted or changes made on the last line.
91: ### Navigation in the Buffer
93: Most vi primers or tutorials start off with navigation, however, not unlike most
94: editors in order to navigate a file there must be something to navigate to and
95: from (hence why this column sort of went in reverse). Depending on your flavor
96: of vi (or if it even *is* vi and not say elvis, nvi or vim) you can navigate in
97: both edit and command mode.
99: For the beginner I feel that switching to command mode and then navigating is a
100: bit safer until one has practiced for awhile. The navigation keys for terminals
101: that are not recognized or do not support the use of arrow keys are the
104: * `k` -- Moves the cursor up one line.
105: * `j` -- Moves the cursor down one line.
106: * `l` -- Moves the cursor right one character.
107: * `h` -- Moves the cursor left one character.
109: If the terminal is recognized and supports them, the arrow keys can be used to
110: navigate the buffer in command mode.
112: In addition to simple *one spot navigation* vi supports jumping to a line by
113: simply typing in the line number at the colon prompt. For example, if you wanted
114: to jump to line 223 the keystrokes from editor mode would look like so:
119: ### Searching a File, the Alternate Navigational Aid
121: The vi editor supports searching using regular expression syntax, however, it is
122: slightly different to invoke from command mode. One simply hits the `/` key in
123: command mode and enters what they are searching for, as an example let us say I
124: am searching for the expression *foo*:
128: That is it, to illustrate a slightly different expression, let us say I am
129: looking for *foo bar*:
131: /foo bar
133: #### Additional Navigation Commands
135: Searching and scrolling are not the only ways to navigate a vi buffer. Following
136: is a list of succinct navigation commands available for vi:
138: * `0` -- Move to beginning of line.
139: * `$` -- Move to end of line.
140: * `b` -- Back up one word.
141: * `w` -- Move forward one word.
142: * `G` -- Move to the bottom of the buffer.
143: * `H` -- Move to the top line on the screen.
144: * `L` -- Move to the last line on the screen.
145: * `M` -- Move the cursor to the middle of the screen.
146: * `N` -- Scan for next search match but opposite direction.
147: * `n` -- Scan for next search match in the same direction.
149: ### A Sample Session
151: Now that we have covered the basics, let us run a sample session using a couple
152: of the items discussed so far. First, we open an empty file into the buffer from
153: the command line like so:
155: # vi foo.txt
157: Next, we switch to edit mode and enter two lines separated by an empty line,
158: remember our buffer is empty so we hit the `i` key to insert before cursor and
159: enter some text:
161: This is some text
163: there we skipped a line
169: Now hit the `ESC` key to switch back into command mode.
171: Now that we are in command mode, let us save the file. First, hit the `:` key,
172: the cursor should be sitting in the lower left corner right after a prompt. At
173: the `:` prompt enter `w` and hit the `ENTER` or `RETURN` key. The file has just
174: been saved. There should have been a message to that effect, some vi editors
175: will also tell you the name, how many lines and the size of the file as well.
177: It is time to navigate, the cursor should be sitting wherever it was when the
178: file was saved. Try using the arrow keys to move around a bit. If they do not
179: work (or you are just plain curious) try out the `hjkl` keys to see how they
182: Finally, let us do two more things, first, navigate up to the first line and
183: then to the first character. Try out some of the other command mode navigation
184: keys on that line, hit the following keys a couple of times:
191: The cursor should hop to the end of line, back to the beginning and then to the
192: end again.
194: Next, search for an expression by hitting the `/` key and an expression like so:
198: The cursor should jump to the *first occurrence* of *we*.
200: Now save the file and exit using write and quit:
204: ## Configuring vi
206: The standard editor supplied with NetBSD is, needless to say, vi, the most loved
207: and hated editor in the world. If you don't use vi, skip this section, otherwise
208: read it before installing other versions of vi. NetBSD's vi (*nvi*) was written
209: by Keith Bostic of UCB to have a freely redistributable version of this editor
210: and has many powerful extensions worth learning while being still very
211: compatible with the original vi. Nvi has become the standard version of vi for
214: Amongst the most interesting extensions are:
216: * Extended regular expressions (egrep style), enabled with option `extended`.
217: * Tag stacks.
218: * Infinite undo (to undo, press `u`; to continue undoing, press `.`).
219: * Incremental search, enabled with the option `searchincr`.
220: * Left-right scrolling of lines, enabled with the option `leftright`; the
221: number of columns to scroll is defined by the `sidescroll` option.
222: * Command line history editing, enabled with the option `cedit`.
223: * Filename completion, enabled by the `filec` option.
224: * Backgrounded screens and displays.
225: * Split screen editing.
227: ### Extensions to `.exrc`
229: The following example shows a `.exrc` file with some extended options enabled.
231: set showmode ruler
232: set filec=^[
233: set cedit=^[
235: The first line enables the display of the cursor position (row and column) and
236: of the current mode (Command, Insert, Append) on the status line. The second
237: line (where \^[ is the ESC character) enables filename completion with the ESC
238: character. The third line enables command line history editing (also with the
239: ESC character.) For example, writing `:` and then pressing ESC opens a window
240: with a list of the previous commands which can be edited and executed (pressing
241: Enter on a command executes it.)
243: ### Documentation
245: The source *tarball* (`src.tgz`) contains a lot of useful documentation on (n)vi
246: and ex, in the `/usr/src/usr.bin/vi/docs` directory. For example:
248: * Edit: A tutorial
249: * Ex Reference Manual
250: * Vi man page
251: * An Introduction to Display Editing with Vi by William Joy and Mark Horton
252: * Ex/Vi Reference Manual by Keith Bostic
253: * Vi Command & Function Reference
254: * Vi tutorial (beginner and advanced)
257: If you have never used vi, the *Vi tutorial* is a good starting point. It is
258: meant to be read using vi and it gradually introduces the reader to all the vi
259: commands, which can be tested while reading. *An Introduction to Display Editing
260: with Vi* by William Joy and Mark Horton is also a very good starting point.
262: If you want to learn more about vi and the nvi extensions you should read the
263: *Ex/Vi Reference Manual* by Keith Bostic which documents all the editor's
264: commands and options.
266: ## Using tags with vi
268: This topic is not directly related to NetBSD but it can be useful, for example,
269: for examining the kernel sources.
271: When you examine a set of sources in a tree of directories and subdirectories
272: you can simplify your work using the *tag* feature of vi. The method is the
275: 1. `cd` to the base directory of the sources.
277: $ cd /path
279: 2. Write the following commands:
281: $ find . -name "*.[ch]" > filelist
282: $ cat filelist | xargs ctags
284: 3. Add the following line to `.exrc`
286: set tags=/path/tags
288: (substitute the correct path instead of *`path`*.)
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