Linux
Edit with vi
vi
is a text editor. It may not be the easiest editor to use,
but it is a standard that is widely used and very powerful. Sooner
or later, if you are required to do any Linux administrative work,
you will need to learn vi. This document is not intended to show
you every feature of vi. It is intended to cover the basics and
get you going so you can start editing text files.
- In this document
all upper/lower case commands should be carefully noted. Commands
in "vi" are case sensitive.
- ^
represents the entry of a control value. It is executed by holding
down the "control key" while pressing the
appropriate letter.
- All commands that
should be entered are printed in bold.
top
of page
From a shell prompt
enter
- vi <filename>
- where <filename>
would be replaced by the name of the file you want to edit.
Example:
vi
myfile
If the file named already
exists, the current contents of the file will be displayed. If
the file named doesn't exist, a new file will be created
I
suggest that you start with a test file that already contains
data.
top
of page
To better understand
vi, think of vi as having different modes of operation.
I like to label the modes as follows:
| Mode |
What
it does |
| Movement |
Allows
you to use arrow keys or other control commands to move
around within existing text |
| Insert |
Allows
you to actually insert new text |
| Change |
Allows
you to change existing text, delete lines, change a
word, change a character, undo changes |
| Colon |
Allows
you to execute global edit commands, read/write to a file,
exit vi and many more options |
| Search |
Allows
you to search for text and change the text |
| Oh
Yeah |
Special
and misc. commands |
top
of page
The simplest method
to move the cursor is to use the arrow keys, up, down, left or
right. Other handy movement commands are...
| Command |
What
it does |
| ^F |
Goes
forward a screen at a time |
| ^B |
Goes
backwards a screen at a time |
| G |
Jumps
to the end of the file |
| #G |
Jumps
to a specific line number. Example: 3G
jumps to line 3 |
| space
bar |
Moves
forward a character at a time |
| backspace
key |
Moves
backwards a character at a time |
| ENTER
key |
Drops
down a line at a time |
| $ |
Jumps
to end of current line |
There are many more,
but for now master the ones above.
top
of page
The first rule to remember
is how to exit insert mode. Every
time you enter insert mode, you have to remember to press ESC
before executing other commands!
| Command |
What
it does |
| ESC
key |
Exit insert mode |
| i |
Insert characters
BEFORE cursor position |
| I |
Insert characters
at BEGINNING of current line (Capital i) |
| a |
Append characters
AFTER cursor position |
| A |
Append characters
at END of current line |
| o |
Open a new line
BELOW current line |
| O |
Open a new line
ABOVE current line |
top
of page
Now that you know how
to insert, let's find out how to change existing text.
| Command |
What
it does |
| R |
Replace
characters starting at cursor position until ESC |
| J |
Join
the line below to the end of the current line |
| rx |
Replace
current character with the letter "x" |
| cw |
Change
the word at the current position up to the first space. Press
ESC after new entry |
| x |
Delete
character at current position |
| #x |
Delete
several characters starting at current position. Example:
3x deletes 3 characters |
| dw |
Delete
the current word |
| dd |
Delete
the current line |
| #dd |
Delete
a number of lines, starting with current line. Example:
3dd will delete 3 lines |
| D |
Delete
from cursor to end of the line |
| u |
Undo
last command |
| U |
Restore
the current line |
top
of page
Now it starts to get
interesting. Let's do the basic colon commands first.
| Command |
What
it does |
| ESC |
Exit
from COLON MODE. It doesn't hurt if
you press ESC more than once |
| : |
Start
COLON MODE. You will jump to the last line on the screen
where a colon will display and await your next command |
| x |
Write
the file and exit |
| q! |
Abort
all changes and exit |
| w |
Write
the file saving current changes, but does not exit vi |
| w
<filename> |
Write
the current file to another file name |
| #,#w
<filename> |
Write
a range of lines of from current file to another file.
Example: 10,20w myfile will write lines
10 to 20 to a file called "myfile" |
| r
<filename> |
Reads
a file and inserts it the line below current position |
| !<command> |
Executes
a shell command. Example: !ls will
list files in the current directory |
| 1,$s/thisvalue/withthis/ |
Performs
global substitution starting at line 1 to end of file. The
"$" sign represents end of file |
| 1,$s/thisvalue/withthis/g |
Same
as above, except this will perform the substitution as many
times as required per line. Without the letter "g"
at the end, the command will only perform the substitution
once per line. Example: 10,20s/Chi /Chicago
/g will change all occurrences of "Chi "
to "Chicago " from line 10 through line 20. Note
the inclusion of the space character after Chi and Chicago.
Without this it would have changed "Chirp" to "Chicagorp" |
| Two
characters that are frequently used in many Linux commands
are the up caret (^) and the dollar sign ($). The up
caret means "at the beginning". The dollar sign
means "at the end". |
| 10,20s/^Chi
/Oswego / |
Changes
the occurrence of "Chi " to "Oswego" only
if the line STARTS with "Chi " |
| 10,20s/01$/99/ |
Changes
the occurrence of "01" to "99" only if
the line ENDS with "01" |
| What
if you want to change a date 01/31/94 to /02/28/94 on the
current line? |
| .s/01\/03\/94/02\/28\/94/ |
- The dot at
the beginning represents the current line only.
- Proceed special
characters, i.e. the "/", with a reverse slash
"\".
- The "\"
tells the command to use the NEXT character
as a parameter and NOT the command separator.
- So if you
want to change a "$" in your command you would
also proceed it by a "\".
|
top
of page
You are editing a large
file of over 3000 lines and you want to find the first occurrence
of "Password". How would you do it?
(That's a forward
slash at the beginning) Like the colon command, the slash
will take you to the last line of the screen. The cursor will
jump to the FIRST occurrence of "Password" from your
current cursor position.
Well that's great,
but now you want to find the NEXT occurrence. Don't fret.
- Enter n
to find the next occurrence of the last
find command.
But now you want to
return to the PREVIOUS occurrence.
- Enter N
too find the previous occurrence.
Instead of the "/"
for FORWARD search, you can use the ?
for BACKWARD search.
- ?Password
- Searches backwards from the current position.
top
of page
Assume you have a large
document and you want to check for "there" vs
"their". You can't use the substitute command
because this would change all occurrences. You may only want to
change selective there's.
- /there
- This will find the first "there"
- cwtheir
and press ESC
- cw changes the word "there" to "their"
- n
- Find the next "there"
- n
- Go on to next "there" and leave the current
"there" as it was
- .
(Yep, just the decimal point.)
This REPEATS the previous EDIT/CHANGE
command
You have 3 lines of
text near the beginning and you want to move this down several
pages to another area. Position the cursor on the first line of
text to move.
- ma
- This marks this location as spot "a"
- Move your cursor
to where you want to relocate
- mb
- This marks this location as spot "b"
- 'a
- This jumps back to marked spot "a"
- Y3
- This yanks 3 lines into buffer memory
- 'b
- This jumps to marked spot "b"
- P
- This puts the yanked text at new
location
- 'a
- This jumps back to mark "a"
- 3dd
- This deletes the 3 lines
The mark
options can also be used just to remember locations. They remain
until you perform another "mX". Valid letters are "a-z".
- ^G
- Display the current file info, current line number, number
of lines in the file and location percentage.
You have now been presented
with the basics. There are many more commands and options for
vi. In your spare time feel free to crack open a vi manual and
learn more.
top
of page
|
