🚀 go-pugleaf

	Chris Seiwald at politik asked about a file he saw with ex/vi
commands at the beginning, and wondered whether this worked.  It does.
The documentation for this is in a report by Mark Horton describing the
changes to vi versions 3.1 through 3.5.  If the first 5 or last 5 lines of
your file contain the following patterns, they will be executed when the
file is read:

	[^:]*ex:valid-ex-commands-including-optional-spaces:
	[^:]*vi:valid-ex-commands-including-optional-spaces:

For example, the line

	/*	ex: set nu ai wm=0 window=23:	*/

at the beginning of a C program will set the modes to number, autoindent,
nowrapmargin, window=23.  The important things about the pattern seem to be:
no colons before the ex or vi, and no space between the ex or vi and the
following colon.

Occasionally this feature will bite you.  The classic problem is editing a
password file where one of the first or last five users has a login ending
in ex.
	tex:Rb.XX/MWDhlj6:801:1:Bob.from.Amarillo:/usr2/tex:/bin/ksh
When you edit the file, vi complains that Rb.XX/MWDhlj6 is not a valid
editor command, but generally keeps working.  (It is possible to create
uneditable files this way, or files that do serious damage to the reader.
Periodic discussions occur about whether this is a feature or a misfeature;
I think it's a very useful feature, but agree that it would be nice to have
a vi option that disables/enables it.
			Bill Stewart
-- 
			Bill Stewart
			AT&T Bell Labs, Holmdel NJ 1-201-949-0705
			...!ihnp4!ho95b!wcs