Difference between revisions of "Vi"

Revision as of 02:47, 7 March 2008

The correct title of this article is vi. The initial letter is capitalized due to technical restrictions.

viis a screen-oriented text editor computer program run from the command line. This article will mainly discuss techniques for vim (vi improved).

Commands

Below is a very short list of the most useful commands:

Examples

• Search and delete lines: This will search for any line starting with "vi" followed by anything and delete that line.

:%g/^vi.*/d

• Filter command: Uses multiple search criteria. This example deletes all lines starting with "ll" or "cd".

:% ! egrep -v "(^ll|^cd)"

External commands

Ctrl-Z   # pause
fg       # resume

Bang!

• find out how many words are in the currently opened file (from the last save):

:! wc %

• check the PHP syntax of the currently opened (php) file:

:! php5 -l %

Reading command output

• to include a list of files from a specific directory, try this read command:

:r ! ls -1 /home/user/path/etc

• grab a page, using lynx, and dump it right into your editing session without leaving vim:

:r ! lynx http://en.wikipedia.org/wiki/Vi -dump 

• etc:

:r ! ls -1 /home/user/directory | sort -r
:r ! grep string /var/log/apache2/site-error.log
:set shell ?   # check the current shell

Appending data

• append current line (under cursor) to external file:

:.w! >> /for/bar

Pre-commands

vi +10 foo

will open the file foo and position the cursor at line 10. Another common usage is to specify a pattern:

vi +/END foo

This will open the file foo and position the cursor at the first occurrence of the pattern 'END'.

Edit binary file in hex format

cp /bin/true /home/bob/mytrue
vi mytrue
# while in vi, [Esc] and
:%!xxd
# now in hex mode, change hex values and then revert back to binary
:%!xxd -r
:wq!

You can also use xxd to transform the file first, edit it, then revert/transform back to binary

xxd mytrue >mytrue.hex
# edit, then
xxd -r mytrue.hex >mytrue.bin

Regular expressions

Switching cases

In the replacement part of a substitution command, i.e. between the second "/" and third "/",

\u means make the following character upper case
\l means make the following character lower case
\U means make the rest of the replacement upper case
\L means make the rest of the replacement lower case

• Make the first letter of every word from line 18 to 43 uppercase:

:18,43s/\<./\u&/g

• Change "uPPeR" and "LoweR" in any mixture of cases to lowercase:

:s/[UuLl][PpOo][PpWw][Ee][Rr]/\L&/

• Make the whole file uppercase:

:%s/.*/\U&/

• Make the region from line m to line n all uppercase:

:'m,'ns/.*/\U&/

• Make a paragraph all lowercase:

:?^$?,/^$/s/.*/\L&/

• Make the first letter of every word in a paragraph uppercase:

:?^$?,/^$/s/\([^ ][^ ]*\)/\u&/g

• Make the second word of each line uppercase:

:1,$s/^\([^ ]*\) \([^ ]*\) \(.*\)/\1 \U\2\e \3/

Misc

Change all lines containing something like the following:

foo      - bar

To:

;foo : bar

%s/^\([a-z].*[a-z]\)[ \t]*- /;\1 : /

Abbreviations

If you are like me and use vi for everything, you will find that there are certain words, phrases, bits of code, etc. that you are constantly using. These can all be stored as abbreviations.

The syntax for storing an abbreviation is as follows:

esc:   # to go into command mode
ab abbr phrase

For an example, say you were editing xhtml, and you wanted 'xzml' to enter standard xml header tags of <?xml version="1.0" encoding="UTF-8" ?>, you could enter:

:ab xzml <?xml version="1.0" encoding="UTF-8" ?>

Then, any time you enter 'xzml' as a word, vi automatically replaces 'xzml' with your standard table tags. The idea is to choose an abbreviation that has no chance of being a real "word", but is short and easy to remember.

Note that the above abbreviation is stored for your current session only. If you wish for it to be universally applicable and available, put the abbreviation command line in your .vimrc file.

To list all of your abbreviations, enter

:ab

Using tabs

vi -p foo1 foo2 foo3

Or, without actual "tabs" but still opening multiple files:

vi foo1 foo2 foo3

Once vi has been started with a list of files it is possible to navigate within the list with the following commands:

:n 

next - Move to the next file in the file list

:rew 

rewind - rewind the file list and open the first file in the list.

Configuring vi/vim

It is possible to extensively configure vi (or vim) to suit your personal needs.

For an example, if you would like syntax-highlighting to be used by default for most of your code files, edit your .vimrc file (located in your "home" directory. If one does not exist, create it) and add the following line:

syn on

Below are some other useful additions:

:set all          # view all current settings
:set nowrapscan   # do not wrap around file when looking for a string
:set number       # add line numbers to left of file
:set noautoindent # do not automatically indent the file
:set report=0     # always report at bottom when any number of lines are yanked
:set ignorecase   # treat capital and small letters the same when searching
:set nobackup     # do _not_ create the ~ files
:set nowritebackup

External links

• Official website
• Vimdoc — the online source for Vim documentation
• Vim Regular Expresions
• Vi Helpfile — by Gábor Egressy
• Vim Cookbook — by Steve Oualline
• Wikibooks : Learning the vi editor