Using the VI Editor
Gregg Wonderly
Mathematics Department
Oklahoma State University
Modified by
John E. Howland
Computer Science Department
Trinity University
4-JAN-1993
1 Introduction
Editing text consists of only a few basic operations. These
operations can be summarized by generalizations to be just
insertions and deletions. Most text editors provide text
insertion capabilities by allowing the user to just type. Text
deletions are then accomplished by the use of certain non-typing
keystrokes which are not allowed to insert text into the document
being edited. These types of editors are typically called
modeless editors, because they apparently have no special mode to
distinguish between inserting and deleting text (just different
keystrokes).
VI is not one of these types of editors. VI is a moded editor,
as it has a specific mode for inserting text, and another mode
(which makes use of the normal typing keys) which allows deleting
text. Like anything different, it can take some time to get used
to this type of editing. There are some real benefits to be
gained from it. Some are quite significant, an others while
perhaps not terribly important, are deeply rooted in the
progression of computers and terminals.
There has never really been a standard terminal with a
standard layout of keys (other than the QWERTY keyboard). This
presents a real problem when you have several different types of
terminals that you use. VI attempts to solve the problem of
dealing with different keyboards by making it unnecessary to use
anything but the QWERTY keyboard.
This is advantageous when a particular site has different types
of terminals. This was the case at the University of California
at Berkeley when Bill Joy first wrote VI. Bill was presented
with the task of writing a full screen editor that would be
usable on all of the terminals that had been given to the
Computer Science folks there. Out of this came two things, VI,
and more importantly, curses which allows terminal independent
access to windowing capabilities.
2 Learning the power of VI
With that out of the way, lets move on to learning VI. There are
two modes of operation that the VI editor can be in. It is
either in command mode, or in insert mode. When you first enter
the editor, it is in command mode. One of the very first things
to learn about VI is, when you are not sure, press the escape
key a few times until you hear a beep. The escape key is used to
change modes from text insert mode to editing command mode, so
pressing it will always get you to command mode, when you are in
insert mode.
VI allows you to perform many tasks with very few keystrokes.
This is good for those who get tired of typing lots of keystrokes
to perform editing operations. This can be bad for those who
make lots of typing mistakes. I say "can be bad" because VI
allows you to recover from typing mistakes by undoing operations
that insert/delete text into/from a document. Operations that
alter a document are explicit in VI. There is a definite
starting point, and a definite ending point. This is what allows
VI to "know" how to undo what you last did. As long as you only
make one mistake at a time, you can undo that mistake by typing a
'u' (for undo) keystroke while in command mode. This is perhaps
the most appreciated feature of VI. There is another key stroke,
'U', which also allows you to undo mistakes. It will undo all
changes made to the current line, providing the cursor has not
left that line since the changes were made.
2.1 Inserting Text
VI incorporates several methods of inserting text into a
document. There are three different methods you can use while
you are in command mode. Typing an 'i' (for insert) keystroke
allows you to insert characters into the document at the point
that the cursor is positioned. As mentioned above, typing the
<ESC> (or escape) keystroke allows you to exit (or escape) from
insert mode. Due to the many different places that a person may
want to insert text at, there are keystrokes other than 'i', that
place the editor directly into insert mode, after moving the
cursor. These are outlined below.
Insert commands
'i' Allows you to insert at the current cursor
position.
'I' Allows you to begin inserting at the beginning
of the line, no matter where the cursor is
positioned on the current line.
Open commands
'o' Allows you to begin inserting on a new, empty
line that is opened for you, below the current
line.
'O' Allows you to begin inserting on a new, empty
line that is opened for you, above the current
line.
Append commands
'a' Allows you to begin inserting after the
character (append) that the cursor is
positioned on.
'A' Allows you to begin inserting at the end of the
current line, no matter where the cursor is
positioned on that line.
There are other commands that place you in insert mode. These
commands are used to perform substitutions of text. That is, the
deletion of old text and the insertion of new text, all in a
single operation. These commands will be discussed further on
because the are actually macros of the change command.
2.2 Deleting Copying and Changing
The next three operations we will discuss will be deleting,
copying, and changing. These three will be discussed together
because the methods of describing the text that these commands
operate on is identical.
There are well over 30 different ways that you can tell VI to
move the cursor to a new location in the document. These
movements can also be used to describe sections of the document
that you wish to perform operations on. Typically, you will type
a single keystroke which describes the type of operation you wish
to perform, e.g. 'd' to delete. There are several commands that
allow you to use a normal movement command to describe a portion
of the document you are editing. These commands are outlined
below.
'd' Delete text.
'y' Copy text (that is, yank it into a holding
area for later use).
'c' Change text from one thing to another, which
you will type.
'!' Filter text through a program.
'<' Shift a region of text to the left.
'>' Shift a region of text to the right.
The first three are the basic text operations that allow you to
alter a document by deleting, copying and changing the text in
it. The last three are more advanced operations that are useful
and handy to have.
3 Single Key Movements
Following one of the commands identifying keystrokes listed in
Figure 1, you must tell VI what portion of the document to
perform the operation on. This is done by typing a keystroke
that indicates a movement command. Most of these are outlined
below. The more complicated movements will be described later
on. Each character is surrounded by single quotes.
'`' Move the cursor to a previously marked location
in the document.
'$' Move the cursor to the end of the current line,
or if a count is specified, to the end of the
(n-1)th line below the current line.
'%' Move the cursor to the matching parenthesis,
bracket or brace.
'^' Move the cursor to the beginning of the line.
'(' Move the cursor to the beginning of the previous
sentence.
')' Move the cursor to the beginning of the next
sentence.
'-' Move the cursor to the first non-blank character
on the previous line.
'+' Move the cursor to the first non-blank character
on the next line.
'w' Move the cursor to the beginning of the next
type of character, where types are alphanumeric,
punctuation, and spaces (words of this type are
commonly refered to as logical words).
'W' Move the cursor to the next space separated
word (words of this type are commonly refered
to as physical words).
'e' Move the cursor to the end of the current type
of character.
'E' Move the cursor to the end of non blank
characters.
't' Move the cursor to the the character preceeding
that cooresponding to the next character typed,
moving forward.
'T' Same as 't' but movement is backward.
'[[' Move the cursor to the beginning of the current
section, where a section is outlined later.
']]' Move the cursor to the beginning of the next
section, where a section is outlined later.
'{' Move the cursor to the beginning of the current
paragraph.
'}' Move the cursor to the beginning of the next
paragraph.
'f' Move the cursor to the next occurance (find
character) of the character corresponding to
the next keystroke typed, moving backwards.
'F' Same as 'f' but movement is backwards.
'G' Move the cursor to the line specified by the
numeric keys typed preceeding this key, or to
the end of the document if none were typed.
'h' Move the cursor to the left one character.
'H' Move the cursor to the top of the Screen, as
opposed to the top of the document which may
not be the same.
'j' Move the cursor to the same column of the line
below the current line.
'k' Move the cursor to the same column of the line
preceeding the current line.
'l' Move the cursor to the right one character.
'L' Move the cursor to the last line on the screen,
as opposed to the last line of the document
which may or may not be the same.
';' Repeat the last 't' or 'f' command, or the last
'F' or 'T' command but in the forward direction.
''' Move the cursor to the first non-space character
of the line that the the indicated marker is set
on.
You probably will not adopt the immediate use of all of these
movements, but it is possible to gain proficency in their use
only by using them.
3.1 Sample Use of the Single Key Movements
Perhaps some sample uses of these movements will make their use a
little more obvious. Typically, a VI manual resolves to give the
reader a list of the most common keystroke combinations, without
trying to describe the real reasoning behind the keystrokes.
This is part of the reason that VI seems so foreign to some
people, they never discover the relationship of all the
keystrokes to one another. However, since I have outlined the
basic relationship of the keystrokes, I feel that I can provide a
similar chart without causing any confusion. The notation <n>
means that you may type one or more of the keys, 0-9, to indicate
a repeat count that will cause the movement indicated to be
performed the indicated number of times. e.g. 5dw will delete
five logical words, 35dd will delete thirty five lines.
3.2 Common Keystroke Combinations
<n>d$ Delete (including the current character),
to the end of the (n-1)th line.
<n>d^ Delete (excluding the current character),
to the beginning of the (n-1)th line.
<n>dE Delete to the end of physical words
(or TO the next space or tab character).
<n>de Delete to the end of logical word.
<n>dd Delete lines.
dG Delete from the current line to the end
of the document.
dH Delete from the current line to the line
shown at the top of the display, inclusive.
<n>dh Delete n characters to the left of the
cursor, 'X' is equivalent to this.
<n>dj Delete the current line, and the n lines
below it.
<n>dk Delete the current line, and the n lines
above it.
<n>dl Delete n characters to the right of the
cursor, including the one under it,
'x' is equivalent to this.
<n>db Delete back to the beginning of the
nth previous logical word.
<n>dB Delete back to the beginning of the
nth previous physical word.
3.3 Glossary
logical word A word that is made up of characters
of a common class. The classes are
alphabetic/numeric and '_',
punctuation, and space or tab.
Physical word A word that is made up of non-space
and non-tab characters. Or put
another way, words made up of
printable characters.