vi.in

早期freebsd实现

Features for editing programs
.PP
The editor has a number of commands for editing programs.
The thing that most distinguishes editing of programs from editing of text
is the desirability of maintaining an indented structure to the body of
the program.  The editor has a
.I autoindent
facility for helping you generate correctly indented programs.
.PP
To enable this facility you can give the command \fB:se ai\fR\s-2CR\s0.
Now try opening a new line with \fBo\fR and type some characters on the
line after a few tabs.  If you now start another line, notice that the
editor supplies white space at the beginning of the line to line it up
with the previous line.  You cannot backspace over this indentation,
but you can use \fB^D\fR key to backtab over the supplied indentation.
.PP
Each time you type \fB^D\fR you back up one position, normally to an
8 column boundary.  This amount is settable; the editor has an option
called
.I shiftwidth
which you can set to change this value.
Try giving the command \fB:se sw=4\fR\s-2CR\s0
and then experimenting with autoindent again.
.PP
For shifting lines in the program left and right, there are operators
.B <
and
.B >.
These shift the lines you specify right or left by one
.I shiftwidth.
Try
.B <<
and
.B >>
which shift one line left or right, and
.B <L
and
.B >L
shifting the rest of the display left and right.
.PP
If you have a complicated expression and wish to see how the parentheses
match, put the cursor at a left or right parenthesis and hit \fB%\fR.
This will show you the matching parenthesis.
This works also for braces { and }, and brackets [ and ].
.PP
If you are editing C programs, you can use the \fB[[\fR and \fB]]\fR keys
to advance or retreat to a line starting with a \fB{\fR, i.e. a function
declaration at a time.  When \fB]]\fR is used with an operator it stops
after a line which starts with \fB}\fR; this is sometimes useful with
\fBy]]\fR.
.NH 2
Filtering portions of the buffer
.PP
You can run system commands over portions of the buffer using the operator
\fB!\fR.
You can use this to sort lines in the buffer, or to reformat portions
of the buffer with a pretty-printer.
Try typing in a list of random words, one per line and ending them
with a blank line.  Back up to the beginning of the list, and then give
the command \fB!}sort\fR\s-2CR\s0.  This says to sort the next paragraph
of material, and the blank line ends a paragraph.
.NH 2
Commands for editing \s-2LISP\s0
.PP
If you are editing a \s-2LISP\s0 program you should set the option
.I lisp
by doing
\fB:se\ lisp\fR\s-2CR\s0.
This changes the \fB(\fR and \fB)\fR commands to move backward and forward
over s-expressions.
The \fB{\fR and \fB}\fR commands are like \fB(\fR and \fB)\fR but don't
stop at atoms.  These can be used to skip to the next list, or through
a comment quickly.
.PP
The
.I autoindent
option works differently for \s-2LISP\s0, supplying indent to align at
the first argument to the last open list.  If there is no such argument
then the indent is two spaces more than the last level.
.PP
There is another option which is useful for typing in \s-2LISP\s0, the
.I showmatch
option.
Try setting it with
\fB:se sm\fR\s-2CR\s0
and then try typing a `(' some words and then a `)'.  Notice that the
cursor shows the position of the `(' which matches the `)' briefly. 
This happens only if the matching `(' is on the screen, and the cursor
stays there for at most one second.
.PP
The editor also has an operator to realign existing lines as though they
had been typed in with
.I lisp
and
.I autoindent
set.  This is the \fB=\fR operator.
Try the command \fB=%\fR at the beginning of a function.  This will realign
all the lines of the function declaration.
.PP
When you are editing \s-2LISP\s0,, the \fB[[\fR and \fR]]\fR advance
and retreat to lines beginning with a \fB(\fR, and are useful for dealing
with entire function definitions.
.NH 2
Macros
.PP
.I Vi
has a parameterless macro facility, which lets you set it up so that
when you hit a single keystroke, the editor will act as though
you had hit some longer sequence of keys.  You can set this up if
you find yourself typing the same sequence of commands repeatedly.
.PP
Briefly, there are two flavors of macros:
.IP a)
Ones where you put the macro body in a buffer register, say \fIx\fR.
You can then type \fB@x\fR to invoke the macro.  The \fB@\fR may be followed
by another \fB@\fR to repeat the last macro.
.IP b)
You can use the
.I map
command from
.I vi
(typically in your
.I EXINIT )
with a command of the form:
.DS
:map \fIlhs\fR \fIrhs\fR\s-2CR\f0
.DE
mapping
.I lhs
into
.I rhs.
There are restrictions:
.I lhs
should be one keystroke (either 1 character or one function key)
since it must be entered within one second
(unless
.I notimeout
is set, in which case you can type it as slowly as you wish,
and
.I vi
will wait for you to finish it before it echoes anything).
The
.I lhs
can be no longer than 10 characters, the
.I rhs
no longer than 100.
To get a space, tab or newline into
.I lhs
or
.I rhs
you should escape them with a \fB^V\fR.
(It may be necessary to double the \fB^V\fR if the map
command is given inside
.I vi,
rather than in
.I ex.)
Spaces and tabs inside the
.I rhs
need not be escaped.
.PP
Thus to make the \fBq\fR key write and exit the editor, you can give
the command
.DS
:map q :wq\fB^V^V\fP\s-2CR CR\s0
.DE
which means that whenever you type \fBq\fR, it will be as though you
had typed the four characters \fB:wq\fR\s-2CR\s0.
A \fB^V\fR's is needed because without it the \s-2CR\s0 would end the
\fB:\fR command, rather than becoming part of the
.I map
definition.
There are two
.B ^V 's
because from within
.I vi ,
two
.B ^V 's
must be typed to get one.
The first \s-2CR\s0 is part of the
.I rhs ,
the second terminates the : command.
.PP
Macros can be deleted with
.DS
unmap lhs
.DE
.PP
If the
.I lhs
of a macro is ``#0'' through ``#9'', this maps the particular function key
instead of the 2 character ``#'' sequence.  So that terminals without
function keys can access such definitions, the form ``#x'' will mean function
key
.I x
on all terminals (and need not be typed within one second.)
The character ``#'' can be changed by using a macro in the usual way:
.DS
:map \fB^V^V^I\fP #
.DE
to use tab, for example.  (This won't affect the
.I map
command, which still uses
.B #,
but just the invocation from visual mode.
.PP
The undo command reverses an entire macro call as a unit,
if it made any changes.
.PP
Placing a `!' after the word
.B map
causes the mapping to apply
to input mode, rather than command mode.
Thus, to arrange for \fB^T\fP to be the same as 4 spaces in input mode,
you can type:
.DS
:map \fB^T\fP \fB^V\fP\o'b/'\o'b/'\o'b/'\o'b/'
.DE
where
.B \o'b/'
is a blank.
The \fB^V\fP is necessary to prevent the blanks from being taken as
white space between the
.I lhs
and
.I rhs .
.NH
Word Abbreviations
.PP
A feature similar to macros in input mode is word abbreviation.
This allows you to type a short word and have it expanded into
a longer word or words.
The commands are
.B :abbreviate
and
.B :unabbreviate
(\fB:ab\fP
and
.B :una )
and have the same syntax as
.B :map .
For example:
.DS
:ab eecs Electrical Engineering and Computer Sciences
.DE
causes the word `eecs' to always be changed into the
phrase `Electrical Engineering and Computer Sciences'.
Word abbreviation is different from macros in that
only whole words are affected.
If `eecs' were typed as part of a larger word, it would
be left alone.
Also, the partial word is echoed as it is typed.
There is no need for an abbreviation to be a single keystroke,
as it should be with a macro.
.NH 2
Abbreviations
.PP
The editor has a number of short
commands which abbreviate longer commands which we
have introduced here.  You can find these commands easily
on the quick reference card.
They often save a bit of typing and you can learn them as convenient.
.NH 1
Nitty-gritty details
.NH 2
Line representation in the display
.PP
The editor folds long logical lines onto many physical lines in the display.
Commands which advance lines advance logical lines and will skip
over all the segments of a line in one motion.  The command \fB|\fR moves
the cursor to a specific column, and may be useful for getting near the
middle of a long line to split it in half.  Try \fB80|\fR on a line which
is more than 80 columns long.\*(dg
.FS
\*(dg You can make long lines very easily by using \fBJ\fR to join together
short lines.
.FE
.PP
The editor only puts full lines on the display; if there is not enough
room on the display to fit a logical line, the editor leaves the physical
line empty, placing only an @ on the line as a place holder.  When you
delete lines on a dumb terminal, the editor will often just clear the
lines to @ to save time (rather than rewriting the rest of the screen.)
You can always maximize the information on the screen by giving the \fB^R\fR
command.
.PP
If you wish, you can have the editor place line numbers before each line
on the display.  Give the command \fB:se nu\fR\s-2CR\s0 to enable
this, and the command \fB:se nonu\fR\s-2CR\s0 to turn it off.
You can have tabs represented as \fB^I\fR and the ends of lines indicated
with `$' by giving the command \fB:se list\fR\s-2CR\s0;
\fB:se nolist\fR\s-2CR\s0 turns this off.
.PP
Finally, lines consisting of only the character `~' are displayed when
the last line in the file is in the middle of the screen.  These represent
physical lines which are past the logical end of file.
.NH 2
Counts
.PP
Most
.I vi
commands will use a preceding count to affect their behavior in some way.
The following table gives the common ways in which the counts are used:
.DS
.TS
l lb.
new window size	:  /  ?  [[  ]]  \`  \'
scroll amount	^D  ^U
line/column number	z  G  |
repeat effect	\fRmost of the rest\fP
.TE
.DE
.PP
The editor maintains a notion of the current default window size.
On terminals which run at speeds greater than 1200 baud
the editor uses the full terminal screen.
On terminals which are slower than 1200 baud
(most dialup lines are in this group)
the editor uses 8 lines as the default window size.
At 1200 baud the default is 16 lines.
.PP
This size is the size used when the editor clears and refills the screen
after a search or other motion moves far from the edge of the current window.
The commands which take a new window size as count all often cause the
screen to be redrawn.  If you anticipate this, but do not need as large
a window as you are currently using, you may wish to change the screen
size by specifying the new size before these commands.
In any case, the number of lines used on the screen will expand if you
move off the top with a \fB\-\fR or similar command or off the bottom
with a command such as \s-2RETURN\s0 or \fB^D\fR.
The window will revert to the last specified size the next time it is
cleared and refilled.\*(dg
.FS
\*(dg But not by a \fB^L\fR which just redraws the screen as it is.
.FE
.PP
The scroll commands \fB^D\fR and \fB^U\fR likewise remember the amount
of scroll