XVI(1) Unix XVI(1)
19/6/1992
NAME
xvi - multi-file text editor
SYNOPSIS
xvi { -s parameter-assignment } [ -t tag | +number | +/pattern ] {
filename ... }
DESCRIPTION
Xvi (pronounced ecks-vee-eye) is a free, portable, multi-window
implementation of the popular vi(1) editor. It has some useful
enhancements, although, as described below, not all of vi's features
have been implemented yet, and some things work differently from vi.
OPTIONS
The following command-line options are available:
-s parameter-assignment
Set the value of the specified parameter at startup. The
assignment has the same form as when given as an editor command,
i.e:
name=string
for string parameters
name=number
for numeric parameters
name to turn a Boolean parameter on
noname
to turn a Boolean parameter off
-t tag
Edit the file containing the definition specified as tag, at the
start of the definition (as per vi).
+number
Go to the specified line number of the file being edited.
+/pattern
Go to the first occurrence of the specified pattern within the
file being edited. The -r command line option is not supported.
ENHANCEMENTS
Multiple buffers and windows
A buffer is the internal object which holds a file in memory, while a
window is an area of the screen which shows part of a buffer. Every
window references a buffer, even if no file is being edited. The
following commands are available for operating on buffers and windows:
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:buffer
create a new buffer in a new window; can be followed by a
filename, which will be edited in the new buffer.
:split
create a new window on to the current buffer by splitting the
current window in half. The two resulting windows are similar to
viewports on to a single editing buffer, in that changes made in
one window are reflected in the other one.
:close
close the current window; will also close the buffer if this is
the last window on to it.
:x / ZZ
close only the current window. If the window is the only one on
to the buffer, the buffer will be closed as well, writing it
first if it is modified.
g move to the next window.
^W increase the size of the current window (may be given a numeric
prefix, default is one line).
^T decrease the size of the current window (may be given a numeric
prefix, default is one line).
^O make the current window as large as possible.
^] as for vi, but create a new buffer window if appropriate (and if
autosplit allows). Note that the :quit command quits out of the
editor, not out of a window. The :close command is thus the
equivalent of :quit for windows. There is no equivalent of :x or
ZZ for the whole editor; these have been hijacked for operations
on windows. The numeric autosplit parameter specifies the
maximum number of buffer windows that will be created
automatically whenever you either edit more than one file, or use
tags to edit a different file. Undo works per buffer, as do
marks; yank/put and redo (the . command) work over all buffers,
i.e. you can delete from one buffer and put the text into a
different buffer.
File preservation
Rather than use vi's Unix-specific method for preservation, xvi does
periodic preservation of all files currently being edited into
temporary files in the same directory. It tries to do this when you
aren't typing, so that you won't notice the short delay when the
temporary file is written out. Obviously, only changed files are
preserved in this way, and the temporary file is removed once the real
file has been successfully written.
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8-bit character support
Characters with the top bit set are accepted by xvi, but it is not yet
possible to have null ('\0') bytes in a file buffer. How characters
are displayed can be controlled by the cchars and mchars parameters,
which, if set, cause control and meta-characters respectively to be
output unchanged; otherwise they are shown as sequences of printable
characters. Tabs are normally displayed as a series of spaces of the
appropriate length (according to the tabstops parameter); setting list
mode will cause them to be displayed as control characters, as will
unsetting the tabs parameter. How the tab character is displayed is
then under the control of the cchars parameter. You can use the ^_
(control-underscore) command to flip the top bit of the character the
cursor is on. This may be useful on systems where it is otherwise
impossible to enter 8-bit characters.
File formats
Xvi can read and write text files in non-Unix formats. The current
format is given by the value of the format parameter, which may be set
to "unix", "msdos", etc. To see a list of available formats, type
:se fmt=?
Extended regular expressions
vi's magic parameter is superseded by the regextype parameter, which
can take the following values:
tags only ^ and $ are significant (used for tags)
grep like grep(1), but with \< and \> added
egrep
like egrep(1), but with \< and \> added The default is grep.
Note that it is still possible to set or unset magic as in vi;
this will simply result in regextype being set as appropriate.
The sections and paragraphs parameters define egrep-style
patterns to search for, rather than vi's simplistic (and troff-
dependent) character pairs.
Improved replace mode
The R command acts more intelligently when you press return - it
leaves the rest of the current line alone, and just starts replacing
text on the next line, starting at the screen column where you first
typed R.
Command re-execution
As well as the normal named (conjugate) buffers, and the default one
(named @), there exist several extra ones named :, /, ? and !, which
contain the last command lines typed to each of the given commands.
So for instance, @: will re-execute the last ex command, or you can
insert it into your buffer, edit it and then re-execute it (e.g. with
dd@@).
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Jumpscroll
When multiple windows are used, xvi normally has to be able to scroll
individual windows without scrolling the whole screen. This can be
very inefficient on terminals without scrolling regions, so the
jumpscroll parameter is provided to control the editor's scrolling
behaviour. It can be set to one of:
off When the cursor moves outside a window's boundaries, and the new
position is near enough, the window will scroll to the new
position.
on When the cursor moves outside a window's boundaries, the window
will always jump to the new position.
auto A window will scroll only if it can do so efficiently; otherwise
it will jump. The default value is auto. On ISA-type systems
which have memory-mapped displays, hardware character generators
and reasonably fast processors, jumpscroll should generally be
set to off; however, on LCD screens or other displays with a long
image persistence, this may actually make the text more difficult
to read, and many users may be more comfortable with it turned
on. Explicit scroll commands (e.g. ^D and ^E) are not affected
by the jumpscroll parameter.
Colour
There are four new parameters to control screen colours:
colour colour used for text statuscolourcolour used for status
lines roscolour as statuscolour, but for readonly files
systemcolourcolour used for system mode (i.e. subshells and after
termination) These parameters are numeric, and the value means
different things on different operating systems. On Unix, it is an
index into the termcap(5) entries "c0" to "c9", which are assumed to
be colour-setting escape sequences if they are present. If they are
not present, "so" (begin standout mode) and "se" (end standout mode)
are used instead. Values of 0 and 1 give normal text, whereas 2 and
above give standout mode. The default colour for the roscolour
parameter will generally involve red if colours are available; this is
intended to provide a warning to the user that writing the file may
not be possible.
On-line help
A primitive help facility is available; the :help command simply
creates a new buffer window on to a standard help file. The name of
the file which is edited is given by the helpfile string parameter;
the default on Unix versions is "/usr/lib/xvi.help". Note that the
help file buffer will be marked "not editable" when it is created,
which prevents accidental overwriting of the help file even when the
file permissions would allow it.
Miscellaneous
The command :wn (write file and edit next) is provided, as in PC-vi.
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The new edit parameter controls whether a buffer can be modified.
This may be used to implement a nicer version of view(1) than the
standard vi version, since it won't fool you into thinking that
editing the buffer is in any way safe. Be warned: once having set
noedit, it is not possible to do a :set edit any more. It's a one-way
street. In insert and replace modes, ^A has the same meaning as ^@ in
vi, except that it works at any time, not just for the first
character. Also, typing ^Bx where x is the name of a conjugate
buffer, inserts the contents of that buffer into the input stream at
that point. The buffer named < always contains the last thing
inserted, so that ^B< is the same as ^A.
LIMITATIONS
Ex mode
The main area in which xvi is lacking is vi's ex mode, which is not
implemented at all (and neither are edit, e, or open modes). However,
many of the ex commands are available in vi mode as colon commands;
the colon commands that have not been implemented are mostly those
which offer the same functionality as other commands in vi mode. In
particular, abbreviate, append, change, ex, insert, join, open,
recover, unabbreviate, undo, write>>, z and | have not been
implemented as colon commands yet.
Vi mode
In vi mode, the U and = commands are not implemented, although there
is no real reason why they shouldn't be, whilst Q is inappropriate in
the context of xvi, since there is no ex mode.
Parameters
Many of vi's parameters have not been implemented; the command :se all
gives a complete list, with current values, of those that have been.
Miscellaneous
Repeat counts before insertions don't work. Appending to named
buffers is not yet implemented. Typing ^Q in input mode does not mean
the same as ^V; it just inserts a `^Q', assuming it gets as far as the
editor at all. Typing ^W in insert mode does not back up one word as
in vi. It is not possible to interrupt the editor while it is
performing certain operations. If you start off a big global command,
you have to wait for it to finish. Flags and counts after ex mode
commands are not supported. It is not possible to read the output of
a system command using
:r !command or to write into a command using
:w !command. Regular expressions, although implemented (see
above), do not support the ~ metacharacter; also, the \u and \l
escape sequences are not supported in substitute replacement
patterns. Newlines included on the right hand side of a
substitution do not currently cause the line to be split; the
newline character is literally inserted into the line. The
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:global command only supports the commands [lps&~d].
OTHER DIFFERENCES FROM VI
The XVINIT environment variable is read instead of EXINIT. Whilst no
files are sourced automatically, users who wish to have a startup file
can arrange it very easily. sh(1) or ksh(1) users should add this
line to their $HOME/.profile:
XVINIT='source xvi-startup-file'; export XVINIT csh(1) users
should add this to their $HOME/.login:
setenv XVINIT 'source xvi-startup-file' The tags parameter can be
used to specify multiple tags files; these can be separated by
either ``\ '' (backslash space) or ``,'' (comma). Alternate
files are handled slightly differently, owing to the presence of
buffer and window handling. Essentially, when you close a
buffer, its filename is remembered as the alternate file; when
you invoke the ^^ or :e # commands, this file is re-edited. Note
that ^^ edits the alternate file in a new buffer window, if
autosplit allows. Hitting the escape key while in the command
line does not terminate input; instead, it cancels input,
returning the prompt to the beginning of the line. This applies
to input for :, /, ? and !.
FILES
/usr/lib/xvi.helpDefault help file.
SEE ALSO
ex(1), vi(1), termcap(5).
Summary of Differences between Vi and Xvi.
BUGS
+ When the cursor is on the last word of a buffer, the command dw
leaves the last character of the word undeleted.
+ Some screen updates do not get shown properly when buffers are
split, and certain commands (e.g. x) are executed.
+ If you do something like cf.WORD<esc> and then redo it, and the
f. fails, then the WORD<esc> gets taken as normal input. The
rest of the input should really be cancelled when part of a redo
fails.
+ A command of the form :/pat/;+1m. will not work because the
editor incorrectly detects a conflict between source and
destination.
+ The editor in its present form is very inefficient in terms of
CPU cycles.
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+ Most termcap(5) terminal descriptions are only tested with vi(1)
(and possibly rogue(6)). Since xvi is, in some ways, more
demanding than vi in its use of termcap capabilities, it
sometimes exposes bugs or inadequacies in termcap entries. This
applies especially to scrolling regions.
AVAILABILITY
Xvi has been ported to MS-DOS, OS/2, QNX and many different versions
of Unix. Source code is available from the authors.
AUTHORS
Chris and John Downey. Derived from STEVIE, written by Tim Thompson
and Tony Andrews.
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