TEXT EDITING AND DISPLAYING
UNIX provides multiple ways to enter text into files. The most common way is
to use one of the editors. The editors are ed, ex, and vi.
The ed editor is the most basic editor. It is a line editor. A line
editor does not display the text on the screen while you are editing. You have
to display the text, then perform editing functions on a line-by-line
The ex editor is an enhanced version of the ed editor. It
provides much better substitution and addressing capabilities. But it is still
a line editor.
The vi editor is a visual editor built on top of the ex line
editor. Thus vi has the power of visually displaying the text you are
working on while also having a powerful line editor to perform substitutions
and other necessary functions.
The following steps show you how to create a file using the vi screen
editor. It is advisable to learn the ex and vi editors because of
there power and popularity.
- 1. Before you begin using vi you must have your
environment set properly. First type env and press
Return. Notice that a list of variables is displayed on your screen.
Look for the TERM= variable in the list. This variable must be set
before vi will perform correctly.
||Type printenv and press Return.
- 2. To set TERM to a desired terminal type, type
TERM=VT100 and press Return. Replace VT100 with
the type of terminal you are using.
||Type set term=vt100 and press Return.
- 3. Begin editing a file by typing vi file1 and
pressing Return. Notice the screen is cleared and tildes (~) are
placed along the left side. The filename is placed on the bottom line along
with status information. Your screen looks like the following display.
- 4. To enter text, type i; this puts vi
in insert mode. Now type This is a new file created by vi.
and press Esc. Notice you entered a line of text and now the cursor
is at the end of the line.
- 5. To duplicate the line, type yy to
yank it to a register and type p to put it back on the
screen. Notice you now have 2 lines of text that are identical.
- 6. To move up 1 line type k, to move down 1
line type j, to move right 1 character type l, and to
move left 1 character type h.
- 7. To jump to the beginning of the current line type
0. Notice the cursor moves to the beginning of the line.
- 8. To jump to the end of the current line type
$. Notice the cursor moves to the end of the line. Remain in
vi to continue the following steps.
The following steps show you how to interface with ex commands while
- 1. Type :ver and press Return to
display what version of vi/ex you are using. On some systems you will
need to press Return to redisplay the vi screen.
- 2. Write the file to disk by typing :w and
pressing Return. On some systems you will need to press
Return again to redisplay the vi screen.
- 3. To substitute a string throughout the file (global
substitute) type :%s/a new/an old/g and press Return.
Notice that both lines changed from having the string "a new" to having "an
old." The percent sign (%) tells ex to search lines 1 through
end-of-file (EOF). The "s" tells ex to perform a substitution. The "/a
new/an old/" says to search for "a new" and change it to "an old." The g
tells ex to change all occurrences on a line. The default is to change
the first occurrence on each line. Press Return.
- 4. To escape to the shell type :sh and press
Return. Notice a shell prompt appears on your terminal; you have
been placed in a new subshell. You may execute any normal UNIX command. To
return to vi/ex press Ctrl-D and then press
- 5. To execute a UNIX command without leaving the editor
type :!cat % and press Return. The % is expanded by
vi into the current buffer name (file1). The command cat file1 is
executed and control is returned to vi.
- 6. To save the file to disk and exit vi type
ZZ (capital letters).