Vi Editor

What is vi?

The default editor that comes with the UNIX operating system is called vi (visual editor). [Alternate editors for UNIX environments include pico and emacs, a product of GNU.]

The UNIX vi editor is a full screen editor and has two modes of operation:

Command mode commands which cause action to be taken on the file, and

Insert mode in which entered text is inserted into the file.

In the command mode, every character typed is a command that does something to the text file being edited; a character typed in the command mode may even cause the vi editor to enter the insert mode. In the insert mode, every character typed is added to the text in the file; pressing the <Esc> (Escape) key turns off the Insert mode.

While there are a number of vi commands, just a handful of these is usually sufficient for beginning vi users. To assist such users, this Web page contains a sampling of basic vi commands. The most basic and useful commands are marked with an asterisk (* or star) in the tables below. With practice, these commands should become automatic.

NOTE: Both UNIX and vi are case-sensitive. Be sure not to use a capital letter in place of a lowercase letter; the results will not be what you expect.

To Get Into and Out Of vi

To Start vi

To use vi on a file, type in vi filename. If the file named filename exists, then the first page (or screen) of the file will be displayed; if the file does not exist, then an empty file and screen are created into which you may enter text.

* vi filename - edit filename starting at line 1

  vi -r filename - recover filename that was being edited when system crashed

Inserting or Adding Text

The following commands allow you to insert and add text. Each of these commands puts the vi editor into insert mode; thus, the <Esc> key must be pressed to terminate the entry of text and to put the vi editor back into command mode.

* i - insert text before cursor, until <Esc> hit

   I - insert text at beginning of current line, until <Esc>hit

* a - append text after cursor, until <Esc>hit

  A - append text to end of current line, until <Esc>hit

Moving the Cursor

Unlike many of the PC and MacIntosh editors, the mouse does not move the cursor within the vi editor screen (or window). You must use the the key commands listed below. On some UNIX platforms, the arrow keys may be used as well; however, since vi was designed with the Qwerty keyboard (containing no arrow keys) in mind, the arrow keys sometimes produce strange effects in vi and should be avoided.

If you go back and forth between a PC environment and a UNIX environment, you may find that this dissimilarity in methods for cursor movement is the most frustrating difference between the two.

In the table below, the symbol ^ before a letter means that the <Ctrl> key should be held down while the letter key is pressed.

* j or <Return> [or down-arrow] - move cursor down one line

* k [or up-arrow] - move cursor up one line

* h or<Backspace> [or left-arrow] - move cursor left one character.

* l or<space> [or right-arrow] - move cursor right one character.

Changing Text

The following commands allow you to modify text.

   cw - change the current word with new text,starting with the character under cursor, until <Esc> hit.

   cc - change (replace) the entire current line, stopping when <Esc> is hit.

    c  - change (replace) the characters in the current line, until <Esc> hit.

    R - replace characters, starting with current cursor position, until <Esc> hit.

Deleting Text

The following commands allow you to delete text.

*  x - delete single character under cursor.

*  d - delete entire current line.

   D - delete the remainder of the line, starting with current cursor position.

 dw - delete the single word beginning with character under cursor.

Cutting and Pasting Text

The following commands allow you to copy and paste text.

  yy - copy (yank, cut) the current line into the buffer.

 yw - copy forward one word.

    p - put (paste) the line(s) in the buffer into the text after the current line.

To Save and Exit vi

Usually the new or modified file is saved when you leave vi. However, it is also possible to quit vi without saving the file.

Note: The cursor moves to bottom of screen whenever a colon (:) is typed. This type of command is completed by hitting the <Return> (or <Enter>) key.

   Esc + shift

: w<Return> - write current contents to file named in original vi call.

: q<Return> - quit ( or exit ) vi

: wq<Return> - quit vi, writing out modified file to file named in original invocation.