vi environment variables

set
you can customize your environment with this command by typing set var=value, this will set the specified var to value for a scalar variable. For boolean varaibles, use set var to set and set novar to unset. You can see which variables are set by just typing the set by its itself. You can see a list of all variables by typing set all. some environment variables are specific to the ex editor and some are specific to the vi editor.

boolean variables:

autoindent(ai)	begin editing next line at same level of indent-ion as this one.
autowrite(aw)	write current buffer before leaving
exrc(ex)	tells vi/ex if it should read the .exrc file in the current directory(this can be a security risk).
errorbells	editor sends a beep to the terminal when an incorrect
flash	inverse the screen on an error instead of producing a bell
ignorecase(ic)	ignore case of characters in searches.
lisp	enter lisp mode
list	place a $ at the end of each line and a ^I on each tab.
magic	allow ., [, and * to be interpreted as special characters in RE's.
modelines	execute the first and last 5 lines of the file if of the form: ex:command: or vi:command:
number(nu)	number lines in left margin
showmatch(sm)	when closing a paren., brace or bracket; move the visual cursor to opening item to check scope
showmode(smd)	show type of insert mode
wrapscan(ws)	when searching and at bottom of file, continue searching from the top

Scalar variables:

directory	the location of the temporary directory used by vi
paragraphs(para)	macros to signify the beginning of a paragraph
report	vi will notify you if you change more lines than the value of report
sections(sect)	macros to signify the beginning of a section
shell	The shell to use when executing the command :sh or :!
shiftwidth(sw)	number of spaces to to insert on a shift operation
showmatch(sm)	show the match of ) and } when typed
tabstop	the length, in characters, of a tabstop
term	holds the name of the terminal type being used
wrapmargin(wm)	split lines at the column which is equal to the value of wrapmargin