R James Taylor

Thanks everyone for reading along. I hope you’ve enjoyed reading these
tips as much as I’ve enjoyed writing them.

For the last installment, I wanted to share a very cool feature in VIM
that I am just beginning to learn how to use. VIM provides support for
Perl, Python and Ruby so that you can use these languages to create
functions in VIM.

I’m most familiar with Python myself, so here are a couple of examples.
In VIM, try the following:

:python print "Hello world"

You’ll see ‘Hello world’ show up in the status line at the bottom of the
screen. Cool, but not all that handy (though you can use this as a
quick calculator, e.g. :py print 256 * 8 ).

To actually get Python to do something interesting with the contents of
your editor, you can define a VIM function that uses Python to do the
heavy lifting.

Here’s how:
:function! PySort()
python << EOF
import vim
b = vim.buffers[0]
x = b[:]
x.sort()
b[:] = x
EOF
endfunction

The :function! line begins a function definition. VIM has its own
internal scripting language, which is swell and all, but if you already
have familiarity with one of the other supported languages, you can use
that language to get a jump start on seriously tricking out VIM.

The line:

python << EOF

tells VIM that we’re defining a block of Python code. The block will
end with the line “EOF”. The enclosed lines are pure Python.

First, we import the vim module:

import vim

Now we have access to that module’s components, like the buffers[]
list. Just like in normal Python, buffers[] is zero-indexed, so
buffers[0] is the first buffer.

Next, we copy the contents of b as a list into the variable x:

x = b[:]

Then we sort that list alphabetically:

x.sort()

Then we replace the current buffer with the sorted context of x:

b[:] = x

And voila – you can now sort the current buffer alphabetically by
calling the PySort() function:

:call PySort()

This is just a trivial example, but hopefully it gives you some ideas of
what can be done with Python (or Perl, or Ruby) inside of VIM.

To get more information about using scripts in VIM, try the following
help commands in VIM:

:help python-vim
:help perl
:help perl-using
:help ruby-vim

Thank you all for reading. Anyone interested in exploring any of the
topics discussed in this or previous tips should feel free to contact me.

Happy VIMming!

- David Roth

VIM’s got a lot of helpful commands that start with g. Not sure why g,
of all letters, but there you are.

One that I find really helpful when running through Apache
configurations is gf. If you put your cursor over the path to a file
and type:

gf

VIM will open up the file that’s under your cursor. So, given a vhost
like the following:

<VirtualHost *:80>
DocumentRoot /var/www/html
ServerName example.com
</VirtualHost>

If you put your cursor over /var/www/html and type gf, VIM will open up
a directory listing of that directory. Or, if you’ve piped the output
of httpd -S to a file and you put your cursor over the path to a
particular virtual host’s configuration file, you can open it up in the
same way. Note that if you’ve updated the current file and it hasn’t
been written to disk yet, VIM will complain that the current file hasn’t
been saved yet and gf will fail.

Another handy use of g is when you’re editing a file with wrapped
lines. Ever find yourself on a line that is wrapped, and you want to
make a change that’s right below the cursor, so you type j or hit the
down arrow, but the cursor skips right past what you want and goes to
the next line? Don’t you just HATE that? Well, if you type gj or
g<down arrow> instead, the cursor will move according to displayed
lines, not logical lines. Much better.

Finally, my favorite stupid VIM trick. g? will ROT-13 text. Use the
ggVG sequence to highlight your entire file. Then type:

g?

And presto – every alphabetic character is shifted 13 places to the
right in the alphabet. Quick and easy obfuscation.

Happy VIMming!

- David Roth

We went over creating VIM macros in a previous tip. If you save your
macros to a file, you can have VIM run the macro against a file,
effectively creating a batch mode for executing VIM macros.

Let’s say that, for whatever reason, you want to convert a file to all
lower case. Create a file called lower.vim and put in the following lines:

ggVGu
:wq!

Make sure there are carriage returns at the end of each line. Those
commands will jump to the first line (gg), turn on visual highlighting
mode (V), then jump to the last line (G). The ‘u‘ command at the end of
the first line will translate all highlighted characters to lower case.
Then the next line writes and quits the file.

Now you can apply this script to any file with:

vim -s lower.vim /path/to/file

Maybe you want to translate all your XML files under the current
directory to lower case. In that case, you can combine VIM with ‘find’
to do some quick batch processing:

find . -type f -name \*.xml -exec vim -s lower.vim {} \;

Note that when you use VIM in this way, VIM does not operate in the
background. An instance of VIM is started for each file being
processed, and the commands in the script file are run like a macro. If
your script file makes a lot of complicated changes, this can be really
amusing to watch. I run this on my computer at home instead of having a
fireplace.

Happy VIMming!

- David Roth

VIM ships with a number of plugins, which are scripts that enhance VIM’s
basic functionality. You’ll find the plugins that shipped with your
copy of VIM in $VIMRUNTIME/plugin.

(Sub-tip: don’t know where VIM is installed? In vim, type “:echo
$VIMRUNTIME“.)

We talked about syntax highlighting in an earlier tip. Syntax
highlighting is great and it makes code more readable, but if you take
your text file that’s all fancy in VIM and publish it on a web page
somewhere, it goes back to dreary black text.

But it doesn’t have to. With a syntax-highlighted file open, type:

ggVG

(that highlights the entire file)

:TOhtml

(that creates an HTML document of your highlighted file)

Cool, huh?

Another fun pair of plugins are gzip.vim and tarPlugin.vim. These are
great because you don’t have to do anything to activate them – just use
VIM to open a .gz or .tar file (or, for that matter, a .tar.gz file).
VIM will uncompress your gzipped file on the fly and re-compress it when
you’re done editing it. If you’re opening up a .tar file, VIM will give
you a list of the files in the tarball.

Happy VIMming!

- David Roth

VIM has a bunch of built-in event handlers which can be used to automate
certain tasks. These are known as autocommands. You can define actions
that get executed whenever one of these autocommands is fired to do
things like read in a template file or write a note to a log file. In
today’s tip, I’m going to show you how to use template files for certain
file types.

Let’s say you write a lot of HTML code, and you always find yourself
creating the following structure:

<HTML>
<HEAD><TITLE></TITLE></HEAD>
<BODY>

</BODY>
</HTML>

Instead of having to type that every single time you create a new .html
file, you can write that structure into a template file. In your home
directory, there should be a .vim directory. If there isn’t go ahead
and create one, then create a directory called templates and write your
template file under the name html.tpl.

Now, add the following line to your .vimrc:

:autocmd BufNewFile *.html 0r ~/.vim/templates/html.tpl

That line tells VIM that you’re defining a new autocommand that is to be
executed when the BufNewFile action is triggered. BufNewFile gets
triggered every time a new file is created in vim. In this case, if the
new file’s name matches the pattern “*.html”, it’s going to read in the
contents of ~/.vim/templates.html.tpl. So now, if you type:

vim brandnewfile.html

VIM is going to create the new file and read in the contents of your
HTML template.

One note about this tip – I have no idea what the 0 in “0r” is for. If
anyone knows why the zero is needed, please let me know.

Happy VIMming!

- David Roth

This is why ninjas are scared of VIM – it allows you to see that which
cannot be seen.  This is a trick that I learned when editing a lot of
Python code in a massive project.  As you may or may not know,
in Python, whitespace is syntactically significant.  Indented lines are
used to indicate the bodies of functions, classes, and loops.  Problems
can arise when bothspaces and tabs are used for indentation, because
Python doesn’t necessarily consider eight spaces to be the equivalent
of two tabs, even though they may look the same to a human eye.

So when you have a file open in VIM and you want to view non-printing
characters, you can turn on list mode to see non-printing characters:

:se list

With list mode enabled, tabs will appear as ^I, carriage returns will
appear as ^M, etc.  To turn list mode off, type:

:se nolist

If you see a character and you’re not sure what it is, you can use
another couple of tricks to view the ASCII value of the character.  Put
your cursor on top of it and type:

ga

(Think “get ASCII”).  If you’re editing a UTF-8 file, the command is:

g8

Then you can look up the value at http://www.asciitable.com/ or
http://www.utf8-chartable.de/ to see what it is. (Unless you’ve memorized the ASCII and UTF-8 tables, in which case you’re probably an emacs user and not interested in these VIM tips anyway.)

Happy VIMming!

- David Roth