7.  Nitty-gritty details

7.1.  Line representation in the display

  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 | 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 80| on a line which is more than 80 columns long (footnote 7-1).

  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 ^R command.

  If you wish, you can have the editor place line numbers before each line on the display. Give the command :se nuCR to enable this, and the command :se nonuCR to turn it off. You can have tabs represented as ^I and the ends of lines indicated with '$' by giving the command :se listCR; :se nolistCR turns this off.

  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.

7.2.  Counts

  Most 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:

new window size    : / ? [[ ]] `
scroll amount    ^D ^U
line/column number    z G |
repeat effect    most of the rest

  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.

  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 - or similar command or off the bottom with a command such as RETURN or ^D. The window will revert to the last specified size the next time it is cleared and refilled (footnote 7-2).

  The scroll commands ^D and ^U likewise remember the amount of scroll last specified, using half the basic window size initially. The simple insert commands use a count to specify a repetition of the inserted text. Thus 10a+----ESC will insert a grid-like string of text. A few commands also use a preceding count as a line or column number.

  Except for a few commands which ignore any counts (such as ^R), the rest of the editor commands use a count to indicate a simple repetition of their effect. Thus 5w advances five words on the current line, while 5RETURN advances five lines. A very useful instance of a count as a repetition is a count given to the . command, which repeats the last changing command. If you do dw and then 3., you will delete first one and then three words. You can then delete two more words with 2..

7.3.  More file manipulation commands

  The following table lists the file manipulation commands which you can use when you are in vi.

:w    write back changes
:wq    write and quit
:x    write (if necessary) and quit (same as ZZ).
:e name    edit file name
:e!    reedit, discarding changes
:e + name    edit, starting at end
:e +n    edit, starting at line n
:e #    edit alternate file
:w name    write file name
:w! name    overwrite file name
:x,yw name    write lines x through y to name
:r name    read file name into buffer
:r !cmd    read output of cmd into buffer
:n    edit next file in argument list
:n!    edit next file, discarding changes to current
:n args    specify new argument list
:ta tag    edit file containing tag tag, at tag

All of these commands are followed by a CR or ESC. The most basic commands are :w and :e. A normal editing session on a single file will end with a ZZ command. If you are editing for a long period of time you can give :w commands occasionally after major amounts of editing, and then finish with a ZZ. When you edit more than one file, you can finish with one with a :w and start editing a new file by giving a :e command, or set autowrite and use :n <file>.

  If you make changes to the editor's copy of a file, but do not wish to write them back, then you must give an ! after the command you would otherwise use; this forces the editor to discard any changes you have made. Use this carefully.

  The :e command can be given a + argument to start at the end of the file, or a +n argument to start at line n. In actuality, n may be any editor command not containing a space, usefully a scan like +/pat or +?pat. In forming new names to the e command, you can use the character % which is replaced by the current file name, or the character # which is replaced by the alternate file name. The alternate file name is generally the last name you typed other than the current file. Thus if you try to do a :e and get a diagnostic that you haven't written the file, you can give a :w command and then a :e # command to redo the previous :e.

  You can write part of the buffer to a file by finding out the lines that bound the range to be written using ^G, and giving these numbers after the : and before the w, separated by ,'s. You can also mark these lines with m and then use an address of the form 'x,'y on the w command here.

  You can read another file into the buffer after the current line by using the :r command. You can similarly read in the output from a command, just use !cmd instead of a file name.

  If you wish to edit a set of files in succession, you can give all the names on the command line, and then edit each one in turn using the command :n. It is also possible to respecify the list of files to be edited by giving the :n command a list of file names, or a pattern to be expanded as you would have given it on the initial vi command.

  If you are editing large programs, you will find the :ta command very useful. It utilizes a data base of function names and their locations, which can be created by programs such as ctags, to quickly find a function whose name you give. If the :ta command will require the editor to switch files, then you must :w or abandon any changes before switching. You can repeat the :ta command without any arguments to look for the same tag again.

7.4.  More about searching for strings

  When you are searching for strings in the file with / and ?, the editor normally places you at the next or previous occurrence of the string. If you are using an operator such as d, c or y, then you may well wish to affect lines up to the line before the line containing the pattern. You can give a search of the form /pat/-n to refer to the n'th line before the next line containing pat, or you can use + instead of - to refer to the lines after the one containing pat. If you don't give a line offset, then the editor will affect characters up to the match place, rather than whole lines; thus use “+0” to affect to the line which matches.

  You can have the editor ignore the case of words in the searches it does by giving the command :se icCR. The command :se noicCR turns this off.

  Strings given to searches may actually be regular expressions. If you do not want or need this facility, you should

set nomagic
in your EXINIT. In this case, only the characters and $ are special in patterns. The character \ is also then special (as it is most everywhere in the system), and may be used to get at the an extended pattern matching facility. It is also necessary to use a \ before a / in a forward scan or a ? in a backward scan, in any case. The following table gives the extended forms when magic is set.

↑    at beginning of pattern, matches beginning of line
$    at end of pattern, matches end of line
.    matches any character
\<    matches the beginning of a word
\>    matches the end of a word
[str]    matches any single character in str
[str]    matches any single character not in str
[x-y]    matches any character between x and y
*    matches any number of the preceding pattern

If you use nomagic mode, then the . [ and * primitives are given with a preceding \.

7.5.  More about input mode

  There are a number of characters which you can use to make corrections during input mode. These are summarized in the following table.

^H    deletes the last input character
^W    deletes the last input word, defined as by b
erase    your erase character, same as ^H
kill    your kill character, deletes the input on this line
\    escapes a following ^H and your erase and kill
ESC    ends an insertion
DEL    interrupts an insertion, terminating it abnormally
CR    starts a new line
^D    backtabs over autoindent
0^D    kills all the autoindent
↑^D    same as 0^D, but restores indent next line
^V    quotes the next non-printing character into the file

  The most usual way of making corrections to input is by typing ^H to correct a single character, or by typing one or more ^W's to back over incorrect words. If you use # as your erase character in the normal system, it will work like ^H.

  Your system kill character, normally @, ^X or ^U, will erase all the input you have given on the current line. In general, you can neither erase input back around a line boundary nor can you erase characters which you did not insert with this insertion command. To make corrections on the previous line after a new line has been started you can hit ESC to end the insertion, move over and make the correction, and then return to where you were to continue. The command A which appends at the end of the current line is often useful for continuing.

  If you wish to type in your erase or kill character (say # or @) then you must precede it with a \, just as you would do at the normal system command level. A more general way of typing non-printing characters into the file is to precede them with a ^V. The ^V echoes as a character on which the cursor rests. This indicates that the editor expects you to type a control character. In fact you may type any character and it will be inserted into the file at that point (footnote 7-3).

  If you are using autoindent you can backtab over the indent which it supplies by typing a ^D. This backs up to a shiftwidth boundary. This only works immediately after the supplied autoindent.

  When you are using autoindent you may wish to place a label at the left margin of a line. The way to do this easily is to type and then ^D. The editor will move the cursor to the left margin for one line, and restore the previous indent on the next. You can also type a 0 followed immediately by a ^D if you wish to kill all the indent and not have it come back on the next line.

7.6.  Upper case only terminals

  If your terminal has only upper case, you can still use vi by using the normal system convention for typing on such a terminal. Characters which you normally type are converted to lower case, and you can type upper case letters by preceding them with a \. The characters { ~ } | ` are not available on such terminals, but you can escape them as \( \↑ \) \! \'. These characters are represented on the display in the same way they are typed (footnote 7-4).

7.7.  Vi and ex

  Vi is actually one mode of editing within the editor ex. When you are running vi you can escape to the line oriented editor of ex by giving the command Q. All of the : commands which were introduced above are available in ex. Likewise, most ex commands can be invoked from vi using :. Just give them without the : and follow them with a CR.

  In rare instances, an internal error may occur in vi. In this case you will get a diagnostic and be left in the command mode of ex. You can then save your work and quit if you wish by giving a command x after the : which ex prompts you with, or you can reenter vi by giving ex a vi command.

  There are a number of things which you can do more easily in ex than in vi. Systematic changes in line oriented material are particularly easy. You can read the advanced editing documents for the editor ed to find out a lot more about this style of editing. Experienced users often mix their use of ex command mode and vi command mode to speed the work they are doing.

7.8.  Open mode: vi on hardcopy terminals and “glass tty's”

  If you are on a hardcopy terminal or a terminal which does not have a cursor which can move off the bottom line, you can still use the command set of vi, but in a different mode. When you give a vi command, the editor will tell you that it is using open mode. This name comes from the open command in ex, which is used to get into the same mode.

  The only difference between visual mode and open mode is the way in which the text is displayed.

  In open mode the editor uses a single line window into the file, and moving backward and forward in the file causes new lines to be displayed, always below the current line. Two commands of vi work differently in open: z and ^R. The z command does not take parameters, but rather draws a window of context around the current line and then returns you to the current line.

  If you are on a hardcopy terminal, the ^R command will retype the current line. On such terminals, the editor normally uses two lines to represent the current line. The first line is a copy of the line as you started to edit it, and you work on the line below this line. When you delete characters, the editor types a number of \'s to show you the characters which are deleted. The editor also reprints the current line soon after such changes so that you can see what the line looks like again.

  It is sometimes useful to use this mode on very slow terminals which can support vi in the full screen mode. You can do this by entering ex and using an open command.

Acknowledgements

  Bruce Englar encouraged the early development of this display editor. Peter Kessler helped bring sanity to version 2's command layout. Bill Joy wrote versions 1 and 2.0 through 2.7, and created the framework that users see in the present editor. Mark Horton added macros and other features and made the editor work on a large number of terminals and Unix systems.

Appendix: character functions

  This has been moved to the vi(1) manual page.

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