vi survival guide

I wrote this article, or shall we call it crash course, on vi, back in 2006, and published it Nuxified. (it even made a little noise on digg, which was new and cool in those pre-reddit days) I am republishing it here in the hope that somebody may still find it useful. Appendix 2 is now slightly out of date since VIM added tabs (an excellent feature I use all the time)

1. Introduction
2. Basic crash course
3. Other Modes
  3.1. A guide to NORMAL mode
    3.1.1. Movement
    3.1.2. Modifying, Deleting, Copying, Pasting
    3.1.3. Repetition and how to avoid it
  3.2. Ex mode
4. Searching and replacing
APPENDIX. VIM - Vi IMproved
  APPENDIX.1. VISUAL mode
  APPENDIX.2. Multiple Windows
Final Words

1. Introduction

If you are trying to work at a command line in pretty much any Operating System, no matter if it is a GNU/Linux brand such as Ubuntu or Fedora Core, another UNIX-like system like Mac OS X or FreeBSD or even Microsoft Windows, you will most definately need a text editor sooner or later. If you are using a UNIX-like system, like GNU/Linux variants, there are many text editors that may or may not be installed. Luckily there is one de-facto standard: vi is included in almost every GNU/Linux or UNIX distribution. "vi" is a truncation of the word "visual" and has, contrary to popular belief, nothing to do with the Roman number 6. Many people are not too fond of vi, but are, alas, often forced into using it when it is the only known option. You may prefer easier editors like gedit (Gnome), kate (KDE), emacs or ne (command line), but these may not be present when working at the command line. Therefore, it is best to know at least the basics of vi and to understand it a little better; the basics of survival in vi, which you will learn in this guide. Unlike what you may have heard about the invention of the language C, the vi editor was not the idea of some kind of sick joke. It was for real and it served a real purpose. I am writing this in vi.

vi is very old, 1976 to be exact - that is only 6 years after 1970-01-01, which is the second no. 0, the big bang, the birth of Jesus Christ of UNIX system clocks. In the age of informatin and the internet, 30 years is practically a century. Remembering the age can help you to accept it if you do not particularly like it. Still, however, many people like the fact that they can memorize the keystrokes and be at home with it for quick tasks, and they like its tiny footprint of disk space and RAM. They like it both as the old reliable standard on most distributions of GNU/Linux and as a simple but powerful editing tool.

The vi editor has an interesting history. It was created in a Berkeley University dorm room, Evans Hall, in 1976 by Bill Joy and some of his friends, although he was the one who fleshed most of it out, using the Pascal language. He designed it for a version of Unix he was working on at Berkeley University called BSD Unix, which stands for Berkeley Software Distribution Unix and forms the base of some modern Unices such as the polular FreeBSD. Bill Joy eventually moved on to Sun Microsystems as one of its original founding members and has since moved on to other projects. Before Bill wrote vi, the students at the university were using an editor called ed. The ed tool, still as widespread as vi, unfortunately, is much harder to use. The students discovered that they could use terminal escape codes so that the terminal moved the cursor to the bottom, and they dubbed this "open mode" where short commands could be typed. There were later derivatives of the ed tool called em and en, and students were experimenting with reprogramming each and borrowing each other's features. Eventually the most popular became Bill's project, vi. When the VAX came about, the terminal escape codes standardized as VT100 (Vax Terminal 100) and this carried over into the BSD Unix and is still there today, implemented, for example, in the Linux console and xterm. These codes were utilized in moving the cursor around in the editor, scrolling sections, blocking off certain sections so that they do not scroll, and other cursor movement features. Anyway, what is most important to note about vi's history is that there was very limited memory and disk space, so commands seemed to be more efficient if they were short keystrokes, rather than typing words. Also, menus and even a mouse weren't invented yet at XEROX PARC center, so short keystroke commands seemed to fit the ticket. Dan Bricklin's Visicalc program would later hinge off of that aspect and use keystrokes the brought up menus, and that approach led to the success of Lotus 1-2-3. So short keystrokes it became, and each of us who use Linux should get to know how to survive in using these keystrokes. Like many things in Unix and Linux, when enough people know about a command and depend on it, it becomes one of the defacto items that just has to be rolled in with it, like it or leave it, or enough people will complain.

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2. Basic crash course

Let's start with the most basic vi knowledge - what you will need to use vi when it is the only choice. vi is different from most editors in that it has different so-called modes. When you start vi, you are in NORMAL mode. Here every key has some special function. For example, pressing 'x' deletes the character under the cursor. Beginners will start off preferring the INSERT mode; you enter it by pressing 'i' in NORMAL mode. Here letters are letters, backspace is backspace etc - like in any old editor. This is a kind of "safe" mode for beginners, as, unlike in NORMAL mode, keys don't do unexpected things. When you have made the changes you want, switch back to NORMAL mode by pressing <ESC>. You can always return to insert mode by pressing i. Now you will want to do some special things such as saving. Here are some command you should know:

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3. Other Modes

By now you should be able to survive in vi for a quick config file edit, code hack or simple ASCII art.But vi is a lot more than insert mode...

3.1. A guide to NORMAL mode

Normal mode is, as you may have gathered or guessed the vi mode. You can do almost anything from inside NORMAL mode.

3.1.1. Movement

Even in NORMAL mode, you can use the arrow keys to navigate, but this always means moving your hand from the letters to the arrow keys and back, resulting in some latency. On laptop keyboards, this is especially inconvieneant. Instead, vi offers the following movement keys:

On most keyboards, these keys are under a touch typist's right hand and thus very accessible. By the way, vi is a perfect editor to learn touch typing with ! These keys can be memorized in different ways. h and l are the furthest left and right of the set; the letter j looks slightly like it's pointing downward and the key usually has a little stud (for finding the key when touch typing) at the bottom.
Here are some more movement keys, some of which are especially useful in combination with other commands (see next section):

3.1.2. Modifying, Deleting, Copying, Pasting

Obviously, you are in vi to edit text. You could also be in vi to hear beeps when you press some wierd keys, but then you probably wouldn't be reading a guide to vi. You have already learned about INSERT mode, but there is more to it that just 'i' ! To "just" get into INSERT mode, you can use the following commands:

vi also offers simple command for single-character deleting and editing:

Now let's go over to some more larger-scale editing in NORMAL mode, as you seriously don't want to use 'x' or 'X' to delete a paragraph of text, for example. This is also the movement commands from section 3.1.1. become really useful.

for better comprehention, a few examples are in order.

There are also a few special cases, namely:

when you delete, change or yank a line, p and P also operate line-wise: p places the yanked line after the current line, P places it before the current line.

3.1.3. Repetition and how to avoid it

Repetition is annoying and senseless. vi has some features to make your edit easier in this respect. First of all comes the command . (yes, the period.); it repeats the last command. For instance, if your last command was dd, then pressing . deletes another line.
Counts are another very useful feature that let you repeat a command a specific number of times. The syntax is as follows:

This also works for motions that are part of a command. A few examples:

To round the section off, I'll show you some commands that every editor, including Microsoft® Notepad, supports:

Unlike Microsoft® Notepad, vi supports doing this multiple times.

3.2. Ex mode

"ex mode" is a command-line like mode. in it you can type certain longer commands, which are executed by typing <ENTER> There are multiple ways to use it:

Sound familiar ? the saving, editing and quitting commands in section 2 where actually ex mode commands. Here are some important ex mode commands: (without the colon): part in square brackets are optional.

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4. Searching and replacing

Searching and replacing are two very important features when editing text files; just think of how easy it is to lose a line in a large config file or on an enourmous screen. I'll start with the simpler of the two: searching. The commands are issued in NORMAL mode.

This may sound dreadfully complicated to you, who may be thinking along the lines of "regular expression... huh?". Well, don't panic. Regular expressions are a standardized way of expressing patterns to search for. The syntax is not easy to understand and is beyond the scope of this document. So you get the idea what it is, I'll give a few examples: '[0-9]{1,3}' matches any one to three-digit number and 'joe' matches the three letters 'joe' (lowercase) and nothing else. If you're not dealing with special characters, you can forget about the regex buisiness.

Now to replacing. The syntax was inherited from [s]ed, so it will be familiar to the gurus ;) These are ex mode commands, and again use regular expressions, this time with bracket substitution, as it is replacing. (again, you can safely ignore that most of the time)

APPENDIX. VIM - Vi IMproved

There are many vi clones and dereviatives out there. In fact, when you open "vi", you will probably not see the original vi, but a clone like nvi or vim. VIM is probably by far the most advanced clone; it has numerous features that are, among others, interesting for programmers. Here I will explain two features that are, in my eyes, the most interesting additions apart from syntax highlighting, which is enabled with the ex command syntax on: Multiple windows and VISUAL mode.

APPENDIX.1. VISUAL mode

Yes, another mode. In this mode, you can select text and perform operations that usually take a movement as argument. For example, selecting text and pressing 'd' will delete the text. As usual, you enter VISUAL mode from NORMAL mode, but unlike the other modes, VISUAL has multiple (three) sub-modes.

normal VISUAL mode

This is pretty much like selecting in most graphical editors: you select character-wise. Let me show you an example:

Some text text text just to show you what VISUAL mode is all about. As I said this is:
    Some text text text just to show you what VISUAL mode is all about. As I said this is:
        Some text text text just to show you what VISUAL mode is all about. As I said this is:
Some text text text just to show you what VISUAL mode is all about. As I said this is:
    Some text text text just to show you what VISUAL mode is all about. As I said this is:
        Some text text text just to show you what VISUAL mode is all about. As I said this is:

VISUAL LINE

This is a little bit niftier. It selects line-wise, not character-wise. Doing 'd' on VISUAL LINE selected text is like doing 'dd' on all the lines.

Some text text text just to show you what VISUAL mode is all about. As I said this is:
    Some text text text just to show you what VISUAL mode is all about. As I said this is:
        Some text text text just to show you what VISUAL mode is all about. As I said this is:
Some text text text just to show you what VISUAL mode is all about. As I said this is:
    Some text text text just to show you what VISUAL mode is all about. As I said this is:
        Some text text text just to show you what VISUAL mode is all about. As I said this is:

VISUAL BLOCK

This is the niftiest of selection modes. Here you select blocks (duh). I cannot convey this better than with the example below.

Some text text text just to show you what VISUAL mode is all about. As I said this is:
    Some text text text just to show you what VISUAL mode is all about. As I said this is:
        Some text text text just to show you what VISUAL mode is all about. As I said this is:
Some text text text just to show you what VISUAL mode is all about. As I said this is:
    Some text text text just to show you what VISUAL mode is all about. As I said this is:
        Some text text text just to show you what VISUAL mode is all about. As I said this is:

APPENDIX.2. Multiple Windows

Vim has support for splitting the screen into multiple windows. These are not the overlapping windows you know from popular graphical user interfaces, these parts of a split screen as users of GNU Emacs and GNU screen will know. With them you can, for example, edit in one part of the screen and look at a different file or a different part of the current file at the same time. To see what this is, well, grab a copy of vim and try it out ! Here I will only list the most important window-related commands. use the ex command help usr_08 in vim to get to the relevant section in the online documentation.

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Final Words

As you have seen, vi is a complicated, unusual editor with many annoyances to the normal user. Surprisingly, the vi editing model has greatly improved productivity of many, and, if you edit much, like a programmer, could increase your efficiency. But if you actually do decide to seriously learn vi or vim, try to use it exclusively, at least for a time. And, above all, stay away from INSERT mode as much as you can. over-using INSERT mode won't help in the slightest if you want to really use it.

Taming Thunderbird

After setting up Mozilla Thunderbird 3 on my netbook, one of my favourite e-mail clients (alongside KDE's good old KMail), and finally managing to get it to behave, I thought I'd share some tips. I'm using Thunderbird 3.1.10 as shipped by Ubuntu.

Let my server do the spam filtering, okay?

I have a well-trained spamassassin set-up running on my own IMAP server, which takes care of filtering spam out of my inbox, and learns from a "spam" folder I populate by hand (and with a honeypot). Now Thunderbird has its own junk mail controls, and it is actually possible to teach these to play along.

First of all, I want Thunderbird's prominent "junk" button to train good old spamassassin, not just its own filter, by moving messages to the designated spam folder: in Preferences → Security → Junk, select When I mark […] Move them to the account's "Junk" folder.

The next problem is telling Thunderbird that the "Junk" folder is not actually called "Junk". This is done in the account's settings, on the Junk Settings page. Here, you can not only select the folder junk goes into, but also turn Thunderbird's own filter off, in case you're like me and think that one spam filter should bloody well be enough.

When I say delete…

By default, when you delete a message in Thunderbird, it isn't "expunged" until you close the program. This has the unfortunate effect that, when you (re)move messages on one computer, leave it on, and check your inbox on another computer, or your phone, those messages will still be there. This can be extremely confusing, or, at the very least, somewhat annoying. There is a (well-hidden) solution, though (thanks, Ryan): set mail.imap.expunge_after_delete to true in the config editor (Preferences → Advanced → Config Editor).

My archive is my castle

Changing which folder to use as an archive folder is fairly straightforward: it is set on the same configuration page as the "Sent" folder, in case you need to change that: Copies & Folders in the account's settings.

Thunderbird, by default, splits the archive up by year. I'm fine with this setting myself, but I've done some digging and it appears that there are some hidden configuration options to change this. A few weeks ago, Jim Porter added a graphical configuration screen to the upstream Mozilla source code which I expect to see in a release soon. (bug/commit)

Woah, you want to index everything?!

Thunderbird's global search is, in principle, a great feature, but there are some things I just don't want to see when I search for specific messages. This is, especially, spam, and I also like to keep my mailing list archives separate from the body of mail I may want to search. Luckily, Thunderbird lets you exclude specific folders from the global search in the individual folder's properties.

Encrypt, sign

E-Mail is an inherently insecure medium, even if you don't use Yahoo! mail. The situation, however, can be vastly improved by using the (comparatively) popular GnuPG software. For Thunderbird, you'll want the Enigmail extension. I won't waste any more words on it here as it has an excellent configuration wizard and I'm sure you can find more information without me if you want or need it.

Consider the android

Since I got an Android phone, my contacts have lived in Google's ominous data banks. My phone can synchronise with Google, and, as it turns out, so can Thunderbird! The extension I'm using is called Google Contacts (unimaginative but obvious), and it works like a charm. It creates a new address book and takes care that it stays synchronised with Google, both ways. It even supports multiple Google accounts, for the double-faced among us.

The Lightning calendar add-on can also synchronize with your Google account using the Google calendar provider extension. There's a nice graphical tutorial here on how to configure that.

That's it for today. Feel free to leave feedback and suggestions in the comments.

Some thoughts on proprietary software

Just now I read Bradley Kuhn's recent blog post entitled Proprietary Software Licensing Produces No New Value In Society. The argument made is, in essence, that by receiving money for a proprietary license, a developer is paid without doing any work. This argument is, in its simplicity, quite pre-industrial in nature and fundamentally flawed. Let me explain:

Bradley, in your post, you compared software development to constructing houses. The problem with this is that houses aren't copied - they're singletons. We need a better analogy.

Think suits

Let's say you want to buy a new suit. You have a couple of fundamentally different options: you can either contact a tailor, and pay them to make one. This is a very simple model: the tailor works on a suit, knowing that they'll be paid. In the end, you pay them for the actual work involved. It makes a lot of sense. This is akin to custom software development, where one is paid by the hour.

However, there is a cheaper alternative: go to a store and buy a ready-to-wear, off-the-shelf product. It's probably good enough, and you'll pay a lot less. You're actually getting value for money, I'm sure you'll agree that it's perfectly reasonable to pay for this. However, the way the money flows is a lot less direct and obvious:

At the beginning, someone designed the suit you're buying, without being paid (or being paid by a company that isn't getting paid yet). Someone set up a production line, without being paid directly, on the mere speculation that someone might buy the suit. And now, you, the customer, are (in addition to the manufacturing and distribution costs, which don't exist in software development) retroactively paying the designer for the work they might have done years ago.

Instead of clothing, I could have used any number of other examples, such as any kind of engineered hardware, or even books. However, nobody buys custom-tailored books.

With software, in addition to financing speculative work done in the past without direct remuneration, you're usually paying for support, for bug-fixes, and for future upgrades: You are, actually, helping to finance continued work. Here, I'm mostly thinking of small software development shops, not so much big corporations like Oracle or Microsoft. For more of an insider's perspective (I myself am a student and have experience only with custom (web) software development and free software projects), I can recommend a nice article by Virgil Dupras of Hardcoded Software, recently linked on the python-dev list.

There is an ongoing micro-discussion on identi.ca that might interest you.

As a small clarification: I support free software, but I think that a strict interpretation of freedoms 2 and 3 can have its problems in a world governed by markets and money.

Auto-poweroff that server in your cellar

Our cellar houses an old grey box that acts as a home server for the family. It's quite useful in a number of ways, as a file server, web server, database server, and so on. It also, traditionally, had a habit of wasting power—it's so much nicer to just have the machine running when you use it. But, with the wonders of Wake on LAN, even the “I'm too lazy to run into the cellar” argument has lost any validity it might have had.

So much for turning the box on, how about turning it off? Figuring out when nobody is using the machine and then remembering to turn it off as well is hardly a task for a mere mortal. So I wrote a script that does it for me. is_anyone_here.py checks whether anyone is logged in, and looks for any evidence of recent usage. It was written on/for a Debian GNU/Linux (lenny) system with vsftpd and samba, and may require some modifications to work properly in your environment.

Have a look at the whole script after the break.

Read more...

Bringing synergy to the table

Once again, my desk is rather clean (a state that doesn't tend to last for long, let's see how long it holds this time), and I have decided to reintroduce a multi-head setup at my workstation. I've done this twice, and always enjoyed the space, and now I've also seen what it's like to have only a 20in wide flat screen sitting in front of you. In addition to that, I made sure there was a place for my laptop, as the recent acquisition of a PCMCIA network card made it desktop-compatible once again.

To spice things up a bit, and, I'll be honest, to spare myself the tedious labour of stretching toward my laptop whenever I want to use it, I've started using one quite magnificent piece of software called Synergy. What Synergy does is, quite simply, allow me to control my laptop with my desktop's keyboard and mouse (over the network). This feels just like having multiple X11 displays: I just move my mouse pointer off the left edge of my big screen and focus is on my laptop. This allows me, for instance, to have an IRC client running on the wee laptop screen without really being distracting :-)

By the way, the video deliberately placed on the right-hand screen in the photograph is one of Julien Doré's extremely arty «Les Limites»-clips. Grep Youtube for it if you will.

Where's that web SVG support ?

Scalable Vector Graphics (SVG) are a promising technology. We've all known for years that vector graphics are, scalable as they tend to be, a great thing and often more useful than raster-based image formats. SVG in particular is nice because it's

• all text
• an XML-based format, and thus hip in the industry
• an open format
• an open XML-based format, and thus portable and good with stuff like XSL-T.

Web browsers like to boast about their SVG support, it being a hip technology pushed as a web standard by the W³C, and the support isn't bad. Recent versions of Gecko (Firefox etc), Opera, KHTML and WebKit have all implemented a working subset of SVG and are able to display simple images correctly. Some browsers (at least Firefox and Opera) have decent support for XSL-T style sheets, allowing you to display an XML data sheet graphically in a browser by linking a suitable style sheet at the top — I never expected this, but I was pleasantly surprised when I discovered that last year. Also interesting is the support of ECMAScript within SVG, making it possible to play tetris in a vanilla IceWeasel.

What was this stuff called again?

We're talking about scalable vector graphics within a WWW context. The fact that these things are scalable could be used to our advantage, n'est-ce pas ? Let's say you have a website styled with only ems for measuring distance, no pixels or other absolute stuff. Being nice and accessible, having the whole website scale when you hit Ctrl++ or Ctrl+-. Something like <img src="foo.svgz" alt="An illustration of bar" style="width:20em"/> should be just what you need. So, which browser supports that ? Bingo, not a single one !

There is a standard, portable way to include SVG in websites: you use the <object> tag, like so: <object type="image/svg+xml" data="foo.svgz" ...>. This works in pretty much all modern browsers (if you don't count IE7, but why would anyone call that bastard “modern” ?), but it doesn't do what I want it to do: it doesn't scale the graphic. At all. It stubbornly uses the size in the SVG file. If you're lucky, zooming with change the font size in the image, but only the font. What's the point of that, I ask you ? Why bother with scalable vector graphics support if you can't scale them ? Maybe we should call them scriptable vector graphics when using them on the web...