To configure your system, you need to edit text files. Most
of them will be in the /etc directory; and
you will need to su to root to be able to
change them. You can use the easy ee, but in
the long run the text editor vi is worth
learning. There is an excellent tutorial on vi in
/usr/src/contrib/nvi/docs/tutorial, if you
have the system sources installed.
Before you edit a file, you should probably back it up.
Suppose you want to edit /etc/rc.conf. You
could just use cd /etc to get to the
/etc directory and do:
#cp rc.conf rc.conf.orig
This would copy rc.conf to
rc.conf.orig, and you could later copy
rc.conf.orig to
rc.conf to recover the original. But even
better would be moving (renaming) and then copying back:
#mv rc.conf rc.conf.orig#cp rc.conf.orig rc.conf
because the mv command preserves the
original date and owner of the file. You can now edit
rc.conf. If you want the original back,
you would then mv rc.conf rc.conf.myedit
(assuming you want to preserve your edited version) and
then
#mv rc.conf.orig rc.conf
to put things back the way they were.
To edit a file, type
#vi filename
Move through the text with the arrow keys.
Esc (the escape key) puts vi
in command mode. Here are some commands:
xdelete letter the cursor is on
dddelete the entire line (even if it wraps on the screen)
iinsert text at the cursor
ainsert text after the cursor
Once you type i or a,
you can enter text. Esc puts you back in
command mode where you can type
:wto write your changes to disk and continue editing
:wqto write and quit
:q!to quit without saving changes
/textto move the cursor to text;
/Enter (the enter key)
to find the next instance of
text.
Gto go to the end of the file
nGto go to line n in the
file, where n is a
number
to redraw the screen
go back and forward a screen, as they do with
more and view.
Practice with vi in your home directory
by creating a new file with vi
filename and adding and
deleting text, saving the file, and calling it up again.
vi delivers some surprises because it is
really quite complex, and sometimes you will inadvertently issue a
command that will do something you do not expect. (Some people
actually like vi—it is more powerful
than DOS EDIT—find out about the :r
command.) Use Esc one or more times to be sure
you are in command mode and proceed from there when it gives you
trouble, save often with :w, and use
:q! to get out and start over (from your last
:w) when you need to.
Now you can cd to
/etc, su to root, use
vi to edit the file
/etc/group, and add a user to wheel so the
user has root privileges. Just add a comma and the user's login
name to the end of the first line in the file, press
Esc, and use :wq to write
the file to disk and quit. Instantly effective. (You did not
put a space after the comma, did you?)
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