Wills' Projects: Vi, VIm, and Friends

A Brief History

Historically, vi (the "VIsual editor") is a front end to a family of other editors including 'ex' and 'ed'. These are roughly analogous to DOS' edlin.

vi's sources were originally licensed in such a proprietary way that the only way to have vi on Linux-based systems was to use a clone. The most revered is VIm (Vi IMproved), which amongst other plus points has a "minimal" implementation for use as /bin/vi, and extended features [and a "compatibility" mode] when built for use as /usr/bin/vim and/or /usr/bin/gvim (the GUI version).

Even VIm's "minimal" implementation is a bit bloaty for embedded class systems, however, and the alternative you'll find in use will either be a workalike (BWIM editor with vi key bindings), or the vi applet belonging to the 'busybox' utility. As one might suspect, busybox-vi does not implement everything listed here; in other cases, the behaviour differs in some slight way.

Basic Philosophy

Designed for use over a slow network link, vi is one of the most powerful text editors you will ever use. Because you'll probably very rarely use meta-keys other than shift, you should never need to move your hands far from the 'home' position - making vi incredibly efficient in the hands of a touch typist.

Bare Essentials

vi starts in "command mode" by default, where any keypress performs some operation. Some operations leave vi in command mode, and some enter insert mode - from which the Escape key exits at the end of your text entry. Pressing shift often invokes a related variant of some operations (although sometimes it's a different command entirely) - see notes in brackets.

All vi clones support at least the following:

Although there are 'vi' commands to save, it's often less confusing to use the 'ex' command line by pressing : in command mode, where the following are useful:

All 'vi' commands can be repeated by prefixing a number; for example 10j moves ten characters to the left, and 4r replaces a four-character string [with four copies of the character you specify] - compare and contrast to 4s, whereby insert mode means any alternative text [ie, a replacement string of any length].

Advanced Movement

Complex Operations

As well as repeating a command by using a numeric prefix, the more complex commands require an "operating region". There is often a default region, which you override by specifying a movement command.

Miscellany - Cut Buffers

If you've done several delete/change/subsitute/etc commands, 'undo' might not do what you want (especially in 'vi'). There is a ten-level history of such changes, all recoverable with prefixes to p or P [ie., the paste command]. There are also twenty-six lettered buffers, which you can employ at will, viz:

Miscellany - Other

Also useful:

VIm Specifics

VIm has a number of extensions which reflect functionality in modern text editors, including multi-level undo. Relevant controls include: