Often you type the same long phrases over and over in a file. vi and ex have a number of different ways of saving long sequences of commands, both in command mode and in insert mode. When you call up one of these saved sequences to execute it, all you do is type a few characters (or even only one), and the entire sequence is executed as if you had entered the whole sequence of commands one by one.
You can define abbreviations that vi will automatically expand into the full text whenever you type the abbreviation in insert mode. To define an abbreviation, use the ex command:
:ab abbr phrase
abbr is an abbreviation for the specified phrase. The sequence of characters that make up the abbreviation will be expanded in insert mode only if you type it as a full word; abbr will not be expanded within a word.
Suppose in the file practice you want to enter text that contains a frequently recurring phrase such as a difficult product or company name. The command:
abbreviates International Materials Research Center to the initials imrc. Now whenever you type imrc in insert mode, imrc expands to the full text.:ab imrc International Materials Research Center
Keystrokes | Results |
---|---|
ithe imrc | the International Materials Research Center |
:unab abbr
To list your currently defined abbreviations, type:
:ab
The characters that compose your abbreviation cannot also appear at the end of your phrase. For example, if you issue the command:
:ab PG This movie is rated PG
you'll get the message "No tail recursion," and the abbreviation won't be set. The message means that you have tried to define something that will expand itself repeatedly, creating an infinite loop. If you issue the command:
:ab PG the PG rating system
you may or may not produce an infinite loop, but in either case you won't get a warning message. For example, when the above command was tested on a System V version of UNIX, the expansion worked. On a Berkeley version, though, the abbreviation expanded repeatedly, like this:
the the the the the ...
until a memory error occurred and vi quit. We recommend that you avoid repeating your abbreviation as part of the defined phrase.
While you're editing, you may find that you are using a command sequence
frequently, or you may occasionally use a very complex command
sequence.
To save yourself keystrokes, or the time that it takes
to remember the sequence, you can assign the sequence to an unused key
by using the map
command.
The map
command acts a lot like ab
except that you
define a macro for command mode instead of insert mode.
:map
x sequence
Define character x as a sequence of editing commands.
:unmap
x
Disable the sequence defined for x.
:map
List the characters that are currently mapped.
Before you can start creating your own maps, you need to know the keys not used in command mode that are available for user-defined commands:
g K q V v
^A ^K ^O ^T ^W ^X
_ * \ =
(Note: The = is used by vi if Lisp mode is set.)
Depending on your terminal, you may also be able to associate map sequences with special function keys.
With maps you can create simple or complex command sequences. As a simple example, you could define a command to reverse the order of words. In vi, with the cursor as shown:
you can the scroll page
the sequence to put the after scroll would be
dwelp
: delete word, dw
; move to the end of next word,
e
; move one space to the right, l
; put the deleted word
there, p
.
Saving this sequence:
:map v dwelp
enables you to reverse the order of two words at any time in the editing
session with the single keystroke v
.
Note that when defining a map, you cannot simply type certain keys,
such as
[RETURN],
[ESC],
[BACKSPACE],
and
[DELETE]
as part of the command to be mapped, because
these keys already have meaning within ex.
If you want to include one of these keys as part of the command
sequence, you must escape the normal meaning
by preceding the key with ^V
[CTRL-V].
The keystroke ^V
appears in the map as the ^ character.
Characters following the ^V
also
do not appear as you expect.
For example, a carriage return appears as ^M
, escape as ^[
, backspace as
^H
, and so on.
On the other hand, if you want to use a control character as the
character to be mapped,
in most cases all you have to do is hold down the
[CTRL]
key and press the letter key at the same time.
So, for example, all you need to do in order to map ^A
is to type:
:map [CTRL-A]sequence
There are, however, three control characters that must be
escaped with a ^V
. They are
^T
, ^W
, and ^X
.
So, for example, if you want to map ^T
, you must type:
:map [CTRL-V] [CTRL-T]sequence
The use of [CTRL-V] applies to any ex command, not just a map command. This means that you can type a carriage return in an abbreviation or a substitution command. For example, the abbreviation:
:ab 123 one^Mtwo^Mthree
expands to this:
one two three
(Here we show the sequence
[CTRL-V]
[RETURN]
as ^M
, the way it would appear on your screen.)
You can also globally add lines at certain locations. The command:
:g/^Section/s//As you recall, in^M&/
inserts, before all lines beginning with the word Section,
a phrase on a separate line. The &
restores the search pattern.
Unfortunately,
one character always has special meaning in ex commands,
even if you try to quote it with
[CTRL-V].
Recall that the vertical bar (|
)
has special meaning as a separator of multiple ex commands.
You cannot use a vertical bar in insert mode maps.
Now that you've seen how to use [CTRL-V] to protect certain keys inside ex commands, you're ready to define some powerful map sequences.
Assume that you have a glossary with entries like this:
map - an ex command which allows you to associate a complex command sequence with a single key.
You would like to convert this glossary list to nroff format, so that it looks like this:
.IP "map" 10 n An ex command...
The best way to define a complex map is to do the edit once manually, writing down each keystroke that you must type. Then recreate these keystrokes as a map. You want to:
Insert the ms macro for an indented paragraph at the beginning of the line.
Insert the first quotation mark as well (I.IP <">
).
Press [ESC] to terminate insert mode.
Move to the end of the first word (e
) and add a second
quotation mark,
followed by a space and the size of the indent (a<"> 10n
).
Press [RETURN] to insert a new line.
Press [ESC] to terminate insert mode.
Remove the hyphen and two surrounding spaces (3x
) and capitalize the next word (~).
That's quite an editing chore if you have to repeat it more than a few times.
With :map
you can save the entire sequence so that it
can be re-executed with a single keystroke:
:map g I.IP "^[ea" 10n^M^[3x~
Note that you have to "quote" both the
[ESC]
and
[RETURN]
characters with
[CTRL-V].
^[
is the sequence that appears when you type
[CTRL-V]
followed by
[ESC].
^M
is the sequence shown when you type
[CTRL-V]
[RETURN].
Now, simply typing g
will perform the entire series of edits.
At a slow baud rate you can actually see the edits happening individually.
At a fast baud rate it will seem to happen by magic.
Don't be discouraged if your first attempt at key mapping fails.
A small error in defining the map can give very different results
from the ones you expect.
Type u
to undo the edit, and try again.
The examples below will give you an idea of the clever shortcuts possible when defining keyboard maps.
Add text whenever you move to the end of a word:
:map e ea
Most of the time, the only reason you want to move to the end of
a word is to add text. This map sequence puts you in insert mode
automatically.
Note that the mapped key, e
, has meaning in vi.
You're allowed to map a key that is already used by vi,
but the key's normal function will be unavailable as long
as the map is in effect. This isn't so bad in this case, since
the E
command is often identical to e
.
:map K dwElp
We discussed this sequence earlier in the chapter, but now
you need to use E
(assume here, and in the remaining examples,
that the e
command is mapped to ea
).
Remember that the cursor begins on the first of the two words.
Unfortunately, because of the l
command, this sequence
(and the earlier version)
doesn't work if the two words are at the end of a line:
during the sequence, the cursor ends up at the end of the line,
and l
cannot move further right.
Here's a better solution:
:map K dwwP
You could also use W
instead of w
.
Save a file and edit the next one in a series:
:map q :w^M:n^M
Notice that you can map keys to ex commands, but be sure
to finish each ex command with a carriage return.
This sequence makes it easy to move from one file to the next
and is useful when you've opened many short files with one vi
command. Mapping the letter q
helps you
remember that the sequence is similar to a "quit."
Put troff emboldening codes around a word:
:map v i\fB^[e\fP^[
This sequence assumes that the cursor is at the beginning of the
word. First, you enter insert mode, then you type the code for
bold font. In map commands, you don't need to type two backslashes to
produce one backslash. Next, you return to command mode
by typing a "quoted"
[ESC].
Finally, you append the closing troff code at the
end of the word, and you return to command mode.
Notice that when we appended to the end of the word,
we didn't need to use ea
, since this sequence is itself
mapped to the single letter e
.
This shows you that map sequences are allowed to contain
other map commands. (The ability to use nested map sequences is
controlled by vi's remap
option, which is normally
enabled.)
Put troff emboldening codes around a word, even when the cursor is not at the beginning of the word:
:map V lbi\fB^[e\fP^[
This sequence is the same as the previous one, except that it
uses lb
to
handle the additional task of positioning the cursor at the
beginning of the word. The cursor might be in the middle of the
word, so you want to move to the beginning with the b
command.
But if the cursor were already at the beginning of the
word, the b
command would move the cursor to the previous
word instead. To guard against that case,
type an l
before moving back with b
, so that
the cursor never starts on the first letter of the word.
You can define variations of this sequence by replacing the
b
with B
and the e
with Ea
.
In all cases, though, the l
command prevents this sequence
from working if the cursor is at the end of a line.
(You could append a space to get around this.)
Repeatedly find and remove parentheses from around a word or phrase: [1]
[1] From the article by Walter Zintz, in UNIX World, April 1990.
:map = xf)xn
This sequence assumes that you first
found an open parenthesis, by typing /(
followed by
[RETURN]
If you choose to remove the parentheses, then use the map command:
delete the open parenthesis with x
, find the
closing one with f)
, delete it with x
, and
then repeat your search for an open parenthesis with n
.
If you don't want to remove the parentheses (for example,
if they're being used correctly), then don't use the map command:
press n
instead to find the next open parenthesis.
You could also modify the map sequence above to handle matching pairs of quotes.
Place C comments around an entire line:
:map g I/* ^[A */^[
This sequence inserts /*
at the line's beginning
and appends */
at the line's end.
You could also map a substitute command to do the same thing:
:map g :s/.*/\/* & *\//^M
Here, you match the entire line (with .*
), and when you
replay it (with &
), you surround the line with the
comment symbols. Note that you have to escape the /
in the comment.
Safely repeat a long insertion:
:map ^J :set wm=0^M.:set wm=10^M
We mentioned in Chapter 2, Simple Editing
that
vi occasionally has difficulty repeating long insertions
of text when wrapmargin
is set.
This map command is a useful workaround. It temporarily turns off
the wrapmargin (by setting to 0), gives the repeat command, and
then restores the wrapmargin.
Note that a map sequence can combine ex and vi commands.
In the previous example,
even though ^J
is a vi command (it moves the cursor
down a line), this key is safe to map because
it's really the same as the j
command.
There are many keys that either perform the same tasks as other
keys or that are rarely used. However, you should be familiar
with the vi commands before you boldly disable
their normal use by using them in map definitions.
Normally, maps apply only to command mode - after all, in insert mode,
keys stand for themselves and shouldn't be mapped as commands.
However, by adding an exclamation mark (!
) to the map
command,
you can force it to override the ordinary meaning of a key and produce
the map in insert mode. This feature is useful when you find
yourself in insert mode but need to escape briefly to command
mode, run a command, and then return to insert mode.
For example, suppose you just typed a word but forgot to italicize it (or place quotes around it, etc.). You can define this map:
:map! + ^[bi\fI^[ea\fP
Now, when you type a +
at the end of a word, you will surround
the word with troff italicization codes. The +
won't show up
in the text.
The sequence above escapes to command mode (^[
),
backs up to insert the first code (bi\fI
),
escapes again (^[
), and moves ahead to append the
second code (ea\fP
).
Since the map sequence
begins and ends in insert mode, you can continue entering text after
italicizing the word.
Here's another example. Suppose that you've been typing your text, and you realize that the previous line should have ended with a colon. You can correct that by defining this map sequence: [2]
[2] From the article by Walter Zintz, in UNIX World, April 1990.
:map! % ^[kA:^[jA
Now, if you type a %
anywhere along your current line,
you'll append a colon to the end of the previous line.
This command escapes to command mode, moves up a line, and
appends the colon (^[kA:
). The command then
escapes again,
moves down to the line you were on,
and leaves you in insert mode (^[jA
).
Note that we wanted to use uncommon characters (%
and
+
) for the previous map commands.
When a character is mapped for insert mode, you
can no longer type that character as text.
To reinstate a character for normal typing, use the command:
:unmap! x
where x is the character that was previously mapped for insert mode.
Insert-mode mapping is often more appropriate for tying character strings to special keys that you wouldn't otherwise use. It is especially useful with programmable function keys.
Many terminals have programmable function keys. You can usually set up these keys to print whatever character or characters you want using a special setup mode on the terminal. However, keys programmed using a terminal's setup mode only work on that terminal; they may also limit the action of programs that want to set up those function keys themselves.
ex allows you to map function keys by number, using the syntax:
:map #1 commands
for function key number 1, and so on. (It can do this because the editor has access to the entry for that terminal found in either the termcap or terminfo database and knows the escape sequence normally put out by the function key.)
As with other keys, maps apply by default to command mode, but by
using the map!
commands as well, you can define two separate
values for a function key - one to be used in command mode, the other in
insert mode.
For example, if you are a troff user, you might
want to put font-switch codes on function keys.
For example:
:map #1 i\fI^[ :map! #1 \fI
If you are in command mode, the first function key will enter insert
mode, type in the three characters \fI
, and return to command mode.
If you are already in insert mode,
the key will simply type the
three-character troff code.
NOTE: If function keys have been redefined in the terminal's setup mode, the
#
n syntax might not work since the function keys no longer put out the expected control or escape sequence as described in its terminal database entry. You will need to examine the termcap entry (or terminfo source) for your terminal and check the definitions for the function keys. In addition, there are some terminals whose function keys perform only local actions and don't actually send any characters to the computer. Such function keys can't be mapped.
The terminal capabilities
k1
, k2
through k0
describe the first ten function keys.
The capabilities l1
, l2
through l0
describe the remaining function keys.
Using your terminal's setup mode, you can change the control
or escape sequence
output by the function key to correspond with the termcap or
terminfo entry.
(For more information, see the Nutshell Handbook termcap & terminfo.)
If the sequence contains ^M
, which is a carriage return,
press
[CTRL-M].
For instance, in order to have function key 1 available for
mapping, the terminal database entry for your terminal must
have a definition of k1
, such as:
k1=^A@^M
In turn, the definition:
^A@^M
must be what is output when you press that key.
To test what the function key puts out, press the key at the UNIX prompt, followed by a [RETURN] if necessary. The shell should display the sequence output by the function key after trying unsuccessfully to execute it as a UNIX command.
Many keyboards have special keys, such as
[HOME],
[END],
[PAGE UP],
and
[PAGE DOWN]
that duplicate commands in vi.
If the terminal's termcap or terminfo description is
complete,
vi will be able to recognize these keys.
But if it isn't, you can use the map
command to make them
available to vi.
These keys generally send an escape sequence to the computer - an
escape character followed by a string of one or more other characters.
In order to trap the escape, you should press ^V
before
pressing the special key in the map.
For example, to map the
[HOME]
key on the keyboard of an IBM PC to a reasonable vi equivalent,
you might define the following map:
:map [CTRL-V] [HOME]
This appears on your screen as:
:map ^[[H 1G
Similar map commands display as follows:
:map [CTRL-V] [END] G displays :map ^[[Y G :map [CTRL-V] [PAGE UP] ^F displays :map ^[[V ^F :map [CTRL-V] [PAGE DOWN] ^B displays :map ^[[U ^B
You'll probably want to place these maps in your .exrc file.
Note that if a special key generates a long escape sequence
(containing multiple non-printing characters),
^V
quotes only the initial escape
character, and the map doesn't work.
You will have to find the entire escape sequence (perhaps
from the terminal manual) and type it in manually, quoting at the
appropriate points, rather than simply pressing ^V
and then the key.
Named buffers provide yet another way to create "macros" - complex command sequences that you can repeat with only a few keystrokes.
If you type a command line in your text (either a vi sequence
or an ex command preceded by a colon), then delete it
into a named buffer, you can execute the contents of that buffer with
the @
command.
For example, open a new line and enter:
cwgadfly [CTRL-V ][ESC] |
cwgadfly^[
on your screen.
Press
[ESC]
again to exit insert mode, then delete the line
into buffer g by typing "gdd
.
Now, whenever you place the cursor at the beginning of a word and
type @g
, that word in your text will be changed to
gadfly.
Since @
is interpreted as a vi command,
a dot (.) will repeat the entire sequence, even if the buffer
contains an ex command.
@@
repeats the last @
, and u
or U
can
be used to undo the effect of @
.
This is a simple example. @-functions are useful because they can be adapted to very specific commands. They are especially useful when you are editing between files, because you can store the commands in their named buffers and access them from any file you edit. @-functions are also useful in combination with the global replacement commands discussed in Chapter 6, Global Replacement .