[Chapter 4] 4.2 Options When Starting vi

4.2 Options When Starting vi

In this handbook, you have invoked the vi editor with the command:

$ 

vi

 

file

There are other options to the vi command that can be helpful. You can open a file directly to a specific line number or pattern. You can also open a file in read-only mode. Another option recovers all changes to a file that you were editing when the system crashed.

4.2.1 Advancing to a Specific Place

When you begin editing an existing file, you can call the file in and then move to the first occurrence of a pattern or to a specific line number. You can also specify your first movement by search or by line number right on the command line:

$ vi + n file: Opens file at line number n .
$ vi + file: Opens file at last line.
$ vi +/ pattern file: Opens file at the first occurrence of pattern .

In the file practice , to open the file and advance directly to the line containing the word Screen , enter:

Keystrokes Results


vi +/Screen practice

With a screen editor you can scroll 
the page, move the cursor, delete 
lines, and insert characters, while 
seeing the results of your edits as 
you make them.  

S
creen editors are 
very popular, since they allow you 
to make changes as you read

Give the vi command with the option +/ pattern to go directly to the line containing Screen .

As you see in the example above, your search pattern will not necessarily be positioned at the top of the screen.

If you include spaces in the pattern , you must enclose the whole pattern within single or double quotes:


+/"you make"

or escape the space with a backslash:


+/you\ make

In addition, if you want to use the general pattern-matching syntax described in Chapter 6, Global Replacement , you may need to protect one or more special characters from interpretation by the shell with either single quotes or backslashes.

Using +/ pattern is helpful if you have to leave an editing session in the middle. You can mark your place by inserting a pattern such as ZZZ or HERE . Then when you return to the file, all you have to remember is /ZZZ or /HERE .

NOTE: Normally, when you're editing in vi , the wrapscan option is enabled. If you've customized your environment so that wrapscan is always disabled, you might not be able to use +/ pattern . If you try to open a file this way, vi opens the file at the last line and displays the message "Address search hit BOTTOM without matching pattern."

4.2.2 Read-only Mode

There will be times when you want to look at a file but want to protect that file from inadvertent keystrokes and changes. (You might want to call in a lengthy file to practice vi movements, or you might want to scroll through a command file or program). You can enter a file in read-only mode and use all the vi movement commands, but you won't be able to change the file.

To look at a file in read-only mode, enter either:


$
 

vi -R

 

file

or:


$
 

view

 

file

(The view command, like the vi command, can use any of the command-line options for advancing to a specific place in the file.) If you do decide to make some edits to the file, you can override read-only mode by adding an exclamation point to the write command:

:w!

or:


:wq!

If you have a problem writing out the file, see the problem checklists summarized in Appendix D, Problem Checklist .

4.2.3 Recovering a Buffer

Occasionally there is a system failure while you are editing a file. Ordinarily, any edits made after your last write (save) are lost. However, there is an option, -r , which lets you recover the edited buffer at the time of a system crash.

When you first log on after the system is running again, you will receive a mail message stating that your buffer has been saved.

In addition, if you type the command:


$
 

ex -r

or:


$
 

vi -r

you will get a list of any files that the system has saved.

Use the -r option with a file name to recover the edited buffer. For example, to recover the edited buffer of the file practice after a system crash, enter:

$ 

vi -r practice

It is wise to recover the file immediately, lest you inadvertently make edits to the file, and then have to resolve a version skew between the preserved buffer and the newly edited file.

You can force the system to preserve your buffer even when there is not a crash by using the command :pre . You may find it useful if you have made edits to a file, then discover that you can't save your edits because you don't have write permission. (You could also just write a copy of the file out under another name or into a directory where you do have write permission. See the section "Problems Saving Files" in Chapter 1, The vi Text Editor .)