This document provides a quick introduction to vi. (Pronounced vee-eye.) You should be running vi on a file you are familiar with while you are reading this. The first part of this document (sections 1 through 5) describes the basics of using vi. Some topics of special interest are presented in section 6, and some nitty-gritty details of how the editor functions are saved for section 7 to avoid cluttering the presentation here.
There is also a short appendix here, which gives for each character the special meanings which this character has in vi. Attached to this document should be a quick reference card. This card summarizes the commands of vi in a very compact format. You should have the card handy while you are learning vi.
Before you can start vi you must tell the system what kind of terminal you are using. Here is a (necessarily incomplete) list of terminal type codes. If your terminal does not appear here, you should consult with one of the staff members on your system to find out the code for your terminal. If your terminal does not have a code, one can be assigned and a description for the terminal can be created.
Code Full name Type ------------------------------------------------------ 2621 Hewlett-Packard 2621A/P Intelligent 2645 Hewlett-Packard 264x Intelligent act4 Microterm ACT-IV Dumb act5 Microterm ACT-V Dumb adm3a Lear Siegler ADM-3a Dumb adm31 Lear Siegler ADM-31 Intelligent c100 Human Design Concept 100 Intelligent dm1520 Datamedia 1520 Dumb dm2500 Datamedia 2500 Intelligent dm3025 Datamedia 3025 Intelligent fox Perkin-Elmer Fox Dumb h1500 Hazeltine 1500 Intelligent h19 Heathkit h19 Intelligent i100 Infoton 100 Intelligent mime Imitating a smart act4 Intelligent t1061 Teleray 1061 Intelligent vt52 Dec VT-52 Dumb
Suppose for example that you have a Hewlett-Packard HP2621A terminal. The code used by the system for this terminal is `2621'. In this case you can use one of the following commands to tell the system the type of your terminal:
% setenv TERM 2621
$ TERM=2621 $ export TERM
If you want to arrange to have your terminal type set up automatically when you log in, you can use the tset program. If you dial in on a mime, but often use hardwired ports, a typical line for your .login file (if you use csh) would be
setenv TERM `tset - -d mime`
TERM=`tset - -d mime`
After telling the system which kind of terminal you have, you should make a copy of a file you are familiar with, and run vi on this file, giving the command
% vi name
The editor does not directly modify the file which you are editing. Rather, the editor makes a copy of this file, in a place called the buffer, and remembers the file's name. You do not affect the contents of the file unless and until you write the changes you make back into the original file.
In our examples, input which must be typed as is will be presented in bold face. Text which should be replaced with appropriate input will be given in italics. We will represent special characters in SMALL CAPITALS.
The editor command set is independent of the terminal you are using. On most terminals with cursor positioning keys, these keys will also work within the editor. If you don't have cursor positioning keys, or even if you do, you can use the h j k and l keys as cursor positioning keys (these are labelled with arrows on an adm3a).*
(Particular note for the HP2621: on this terminal the function keys must be shifted (ick) to send to the machine, otherwise they only act locally. Unshifted use will leave the cursor positioned incorrectly.)
Several of these special characters are very important, so be sure to find them right now. Look on your keyboard for a key labelled ESC or ALT. It should be near the upper left corner of your terminal. Try hitting this key a few times. The editor will ring the bell to indicate that it is in a quiescent state.*** Partially formed commands are cancelled by ESC, and when you insert text in the file you end the text insertion with ESC. This key is a fairly harmless one to hit, so you can just hit it if you don't know what is going on until the editor rings the bell.
The CR or RETURN key is important because it is used to terminate certain commands. It is usually at the right side of the keyboard, and is the same command used at the end of each shell command.
Another very useful key is the DEL or RUB key, which generates an interrupt, telling the editor to stop what it is doing. It is a forceful way of making the editor listen to you, or to return it to the quiescent state if you don't know or don't like what is going on. Try hitting the `/' key on your terminal. This key is used when you want to specify a string to be searched for. The cursor should now be positioned at the bottom line of the terminal after a `/' printed as a prompt. You can get the cursor back to the current position by hitting the DEL or RUB key; try this now.* From now on we will simply refer to hitting the DEL or RUB key as ``sending an interrupt.''**
The editor often echoes your commands on the last line of the terminal. If the cursor is on the first position of this last line, then the editor is performing a computation, such as computing a new position in the file after a search or running a command to reformat part of the buffer. When this is happening you can stop the editor by sending an interrupt.
After you have worked with this introduction for a while, and you wish to do something else, you can give the command ZZ to the editor. 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 :q!CR;** 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.