vi.in

早期freebsd实现

This will write the contents of the editor's buffer back into
the file you are editing, if you made any changes, and then quit from
the editor.  You can also end an editor
session by giving the command \fB:q!\fR\s-2CR\s0;\*(dg
.FS
\*(dg All commands which read from the last display line can also be
terminated with a \s-2ESC\s0 as well as an \s-2CR\s0.
.FE
this is a dangerous but occasionally essential
command which ends the editor session and discards all your changes.
You need to know about this command in case you change the editor's
copy of a file you wish only to look at.  Be very careful
not to give this command when you really want to save
the changes you have made.
.NH 1
Moving around in the file
.NH 2
Scrolling and paging
.PP
The editor has a number of commands for moving around in the file.
The most useful of these is generated by hitting the control and D keys
at the same time, a control-D or `^D'.  We will use this two character
notation for referring to these control keys from now on.  You may have
a key labelled `^' on your terminal.  This key will be represented as `\(ua'
in this document; `^' is exclusively used as part of the `^x' notation
for control characters.\*(dd
.FS
\*(dd If you don't have a `^' key on your terminal
then there is probably a key labelled `\(ua'; in any case these characters
are one and the same.
.FE
.PP
As you know now if you tried hitting \fB^D\fR, this command scrolls down in
the file.  The \fBD\fR thus stands for down.  Many editor commands are mnemonic
and this makes them much easier to remember.  For instance the command
to scroll up is \fB^U\fR.  Many dumb terminals can't scroll up at all, in which
case hitting \fB^U\fR clears the screen and refreshes it
with a line which is farther back in the file at the top.
.PP
If you want to see more of the file below where you are, you can
hit \fB^E\fR to expose one more line at the bottom of the screen,
leaving the cursor where it is.
The command \fB^Y\fR (which is hopelessly non-mnemonic, but next to \fB^U\fR
on the keyboard) exposes one more line at the top of the screen.
.PP
There are other ways to move around in the file; the keys \fB^F\fR and \fB^B\fR
move forward and backward a page,
keeping a couple of lines of continuity between screens
so that it is possible to read through a file using these rather than
\fB^D\fR and \fB^U\fR if you wish.
.PP
Notice the difference between scrolling and paging.  If you are trying
to read the text in a file, hitting \fB^F\fR to move forward a page
will leave you only a little context to look back at.  Scrolling on the
other hand leaves more context, and happens more smoothly.  You can continue
to read the text as scrolling is taking place.
.NH 2
Searching, goto, and previous context
.PP
Another way to position yourself in the file is by giving the editor a string
to search for.  Type the character \fB/\fR followed by a string of characters
terminated by \s-2CR\s0.  The editor will position the cursor
at the next occurrence of this string.
Try hitting \fBn\fR to then go to the next occurrence of this string.
The character \fB?\fR will search backwards from where you are, and is
otherwise like \fB/\fR.\*(dg
.FS
\*(dg These searches will normally wrap around the end of the file, and thus
find the string even if it is not on a line in the direction you search
provided it is anywhere else in the file.  You can disable this wraparound
in scans by giving the command \fB:se nowrapscan\fR\s-2CR\s0,
or more briefly \fB:se nows\fR\s-2CR\s0.
.FE
.PP
If the search string you give the editor is not present in the
file the editor will print
a diagnostic on the last line of the screen, and the cursor will be returned
to its initial position.
.PP
If you wish the search to match only at the beginning of a line, begin
the search string with an \fB\(ua\fR.  To match only at the end of
a line, end the search string with a \fB$\fR.
Thus \fB/\(uasearch\fR\s-2CR\s0 will search for the word `search' at
the beginning of a line, and \fB/last$\fR\s-2CR\s0 searches for the
word `last' at the end of a line.*
.FS
*Actually, the string you give to search for here can be a
.I "regular expression"
in the sense of the editors
.I ex (1)
and
.I ed (1).
If you don't wish to learn about this yet, you can disable this more
general facility by doing
\fB:se\ nomagic\fR\s-2CR\s0;
by putting this command in
EXINIT
in your environment, you can have this always be in effect (more
about
.I EXINIT
later.)
.FE
.PP
The command \fBG\fR, when preceded by a number will position the cursor
at that line in the file.
Thus \fB1G\fR will move the cursor to
the first line of the file.  If you give \fBG\fR no count, then it moves
to the end of the file.
.PP
If you are near the end of the file, and the last line is not at the bottom
of the screen, the editor will place only the character `~' on each remaining
line.  This indicates that the last line in the file is on the screen;
that is, the `~' lines are past the end of the file.
.PP
You can find out the state of the file you are editing by typing a \fB^G\fR.
The editor will show you the name of the file you are editing, the number
of the current line, the number of lines in the buffer, and the percentage
of the way through the buffer which you are.
Try doing this now, and remember the number of the line you are on.
Give a \fBG\fR command to get to the end and then another \fBG\fR command
to get back where you were.
.PP
You can also get back to a previous position by using the command
\fB\(ga\(ga\fR (two back quotes).
This is often more convenient than \fBG\fR because it requires no advance
preparation.
Try giving a \fBG\fR or a search with \fB/\fR or \fB?\fR and then a
\fB\(ga\(ga\fR to get back to where you were.  If you accidentally hit
\fBn\fR or any command which moves you far away from a context of interest, you
can quickly get back by hitting \fB\(ga\(ga\fR.
.NH 2
Moving around on the screen
.PP
Now try just moving the cursor around on the screen.
If your terminal has arrow keys (4 or 5 keys with arrows
going in each direction) try them and convince yourself
that they work.
If you don't have working arrow keys, you can always use
.B h ,
.B j ,
.B k ,
and
.B l .
Experienced users of
.I vi
prefer these keys to arrow keys,
because they are usually right underneath their fingers.
.PP
Hit the \fB+\fR key.  Each time you do, notice that the cursor
advances to the next line in the file, at the first non-white position
on the line.  The \fB\-\fR key is like \fB+\fR but goes the other way.
.PP
These are very common keys for moving up and down lines in the file.
Notice that if you go off the bottom or top with these keys then the
screen will scroll down (and up if possible) to bring a line at a time
into view.  The \s-2RETURN\s0 key has the same effect as the \fB+\fR
key.
.PP
.I Vi
also has commands to take you to the top, middle and bottom of the screen.
\fBH\fR will take you to the top (home) line on the screen.
Try preceding it with a
number as in \fB3H\fR.
This will take you to the third line on the screen.
Many
.I vi
commands take preceding numbers and do interesting things with them.
Try \fBM\fR,
which takes you to the middle line on the screen,
and \fBL\fR,
which takes you to the last line on the screen.
\fBL\fR also takes counts, thus
\fB5L\fR will take you to the fifth line from the bottom.
.NH 2
Moving within a line
.PP
Now try picking a word on some line on the screen, not the
first word on the line.
move the cursor using \s-2RETURN\s0 and \fB\-\fR to be on the line where
the word is.
Try hitting the \fBw\fR key.  This will advance the cursor to the
next word on the line.
Try hitting the \fBb\fR key to back up words
in the line.
Also try the \fBe\fR key which advances you to the end of the current
word rather than to the beginning of the next word.
Also try \s-2SPACE\s0 (the space bar) which moves right one character
and the \s-2BS\s0 (backspace or \fB^H\fR) key which moves left one character.
The key \fBh\fR works as \fB^H\fR does and is useful if you don't have
a \s-2BS\s0 key.
(Also, as noted just above, \fBl\fR will move to the right.)
.PP
If the line had punctuation in it you may have noticed that
that the \fBw\fR and \fBb\fR
keys stopped at each group of punctuation.  You can also go back and
forwards words without stopping at punctuation by using \fBW\fR and \fBB\fR
rather than the lower case equivalents.  Think of these as bigger words.
Try these on a few lines with punctuation to see how they differ from
the lower case \fBw\fR and \fBb\fR.
.PP
The word keys wrap around the end of line,
rather than stopping at the end.  Try moving to a word on a line below
where you are by repeatedly hitting \fBw\fR.
.NH 2
Summary
.IP
.TS
lw(.50i)b a.
\fR\s-2SPACE\s0\fP	advance the cursor one position
^B	backwards to previous page
^D	scrolls down in the file
^E	exposes another line at the bottom
^F	forward to next page
^G	tell what is going on
^H	backspace the cursor
^N	next line, same column
^P	previous line, same column
^U	scrolls up in the file
^Y	exposes another line at the top
+	next line, at the beginning
\-	previous line, at the beginning
/	scan for a following string forwards
?	scan backwards
B	back a word, ignoring punctuation
G	go to specified line, last default
H	home screen line
M	middle screen line
L	last screen line
W	forward a word, ignoring punctuation
b	back a word
e	end of current word
n	scan for next instance of \fB/\fR or \fB?\fR pattern
w	word after this word
.TE
.NH 2
View
.PP
If you want to use the editor to look at a file,
rather than to make changes,
invoke it as
.I view
instead of
.I vi .
This will set the
.I readonly
option which will prevent you from
accidently overwriting the file.
.NH 1
Making simple changes
.NH 2
Inserting
.PP
One of the most useful commands is the
\fBi\fR (insert) command.
After you type \fBi\fR, everything you type until you hit \s-2ESC\s0
is inserted into the file.
Try this now; position yourself to some word in the file and try inserting
text before this word.
If you are on an dumb terminal it will seem, for a minute,
that some of the characters in your line have been overwritten, but they will
reappear when you hit \s-2ESC\s0.
.PP
Now try finding a word which can, but does not, end in an `s'.
Position yourself at this word and type \fBe\fR (move to end of word), then
\fBa\fR for append and then `s\s-2ESC\s0' to terminate the textual insert.
This sequence of commands can be used to easily pluralize a word.
.PP
Try inserting and appending a few times to make sure you understand how
this works; \fBi\fR placing text to the left of the cursor, \fBa\fR to
the right.
.PP
It is often the case that you want to add new lines to the file you are
editing, before or after some specific line in the file.  Find a line
where this makes sense and then give the command \fBo\fR to create a
new line after the line you are on, or the command \fBO\fR to create
a new line before the line you are on.  After you create a new line in
this way, text you type up to an \s-2ESC\s0 is inserted on the new line.
.PP
Many related editor commands
are invoked by the same letter key and differ only in that one is given
by a lower
case key and the other is given by
an upper case key.  In these cases, the
upper case key often differs from the lower case key in its sense of
direction, with
the upper case key working backward and/or up, while the lower case
key moves forward and/or down.
.PP
Whenever you are typing in text, you can give many lines of input or
just a few characters.
To type in more than one line of text,
hit a \s-2RETURN\s0 at the middle of your input.  A new line will be created
for text, and you can continue to type.  If you are on a slow
and dumb terminal the editor may choose to wait to redraw the
tail of the screen, and will let you type over the existing screen lines.
This avoids the lengthy delay which would occur if the editor attempted
to keep the tail of the screen always up to date.  The tail of the screen will
be fixed up, and the missing lines will reappear, when you hit \s-2ESC\s0.
.PP
While you are inserting new text, you can use the characters you normally use
at the system command level (usually \fB^H\fR or \fB#\fR) to backspace
over the last
character which you typed, and the character which you use to kill input lines
(usually \fB@\fR, \fB^X\fR, or \fB^U\fR)
to erase the input you have typed on the current line.\*(dg
.FS
\*(dg In fact, the character \fB^H\fR (backspace) always works to erase the
last input character here, regardless of what your erase character is.
.FE
The character \fB^W\fR
will erase a whole word and leave you after the space after the previous
word; it is useful for quickly backing up in an insert.
.PP
Notice that when you backspace during an insertion the characters you
backspace over are not erased; the cursor moves backwards, and the characters
remain on the display.  This is often useful if you are planning to type
in something similar.  In any case the characters disappear when when
you hit \s-2ESC\s0; if you want to get rid of them immediately, hit an
\s-2ESC\s0 and then \fBa\fR again.
.PP
Notice also that you can't erase characters which you didn't insert, and that
you can't backspace around the end of a line.  If you need to back up
to the previous line to make a correction, just hit \s-2ESC\s0 and move
the cursor back to the previous line.  After making the correction you
can return to where you were and use the insert or append command again.
.NH 2
Making small corrections
.PP
You can make small corrections in existing text quite easily.
Find a single character which is wrong or just pick any character.
Use the arrow keys to find the character, or
get near the character with the word motion keys and then either
backspace (hit the \s-2BS\s0 key or \fB^H\fR or even just \fBh\fR) or 
\s-2SPACE\s0 (using the space bar)
until the cursor is on the character which is wrong.
If the character is not needed then hit the \fBx\fP key; this deletes
the character from the file.  It is analogous to the way you \fBx\fP
out characters when you make mistakes on a typewriter (except it's not
as messy).
.PP
If the character