.\" Copyright (c) 1994
.\"     The Regents of the University of California.  All rights reserved.
.\" Copyright (c) 1994, 1995, 1996
.\"	Keith Bostic.  All rights reserved.
.\"
.\" This document may not be republished without written permission from
.\" Keith Bostic. 
.\"
.\" See the LICENSE file for redistribution information.
.\"
.\"     @(#)vi.ref	8.88 (Berkeley) 10/19/96
.\"
.\" $FreeBSD: src/contrib/nvi/docs/USD.doc/vi.ref/vi.ref,v 1.2 2005/08/17 15:56:04 cperciva Exp $
.\"
.so ref.so
.tp
.(l C
.ps 12
.ft B
Vi/Ex Reference Manual
.ft
.ps
.sp
.i "Keith Bostic"
.sp
Computer Science Division
Department of Electrical Engineering and Computer Science
University of California, Berkeley
Berkeley, California  94720
.sp 1
.)l
.sp 3
.(l C
.i Abstract
.)l
.(q
.pp
This document is the reference guide for the 4.4BSD
implementations of
.EV nex nvi ,
which are implementations of the historic Berkeley
.EV ex vi
editors.
.)q
.sp 3
.(l C
.i Licensing
.)l
.sp
.lp
Copyright (c) 1991, 1992, 1993, 1994
.ti +5
The Regents of the University of California.  All Rights Reserved.
.lp
Copyright (c) 1991, 1992, 1993, 1994, 1995, 1996
.ti +5
Keith Bostic.  All Rights Reserved.
.sp
.pp
The vi program is freely redistributable.  You are welcome to copy,
modify and share it with others under the conditions listed in the
LICENSE file.  If any company (not individual!) finds vi sufficiently
useful that you would have purchased it, or if any company wishes to
redistribute it, contributions to the authors would be appreciated.
.bp 2
.(l C
.i Acknowledgements
.)l
.sp
.(q
.pp
Bruce Englar encouraged the early development of the historic
.EV ex vi
editor.
Peter Kessler helped bring sanity to version 2's command layout.
Bill Joy wrote versions 1 and 2.0 through 2.7,
and created the framework that users see in the present editor.
Mark Horton added macros and other features and made
.EV ex vi
work on a large number of terminals and Unix systems.
.pp
.CO Nvi
is originally derived from software contributed to the University of
California, Berkeley by Steve Kirkendall, the author of the
.CO vi
clone
.CO elvis .
.pp
IEEE Standard Portable Operating System Interface for Computer
Environments (POSIX) 1003.2 style Regular Expression support was
done by Henry Spencer.
.pp
The curses library was originally done by Ken Arnold.
Scrolling and reworking for
.CO nvi
was done by Elan Amir.
.pp
George Neville-Neil added the Tcl interpreter,
and Sven Verdoolaege added the Perl interpreter.
.pp
Rob Mayoff added Cscope support.
.pp
The Institute of Electrical and Electronics Engineers has
given us permission to reprint portions of their documentation.
Portions of this document are reprinted and reproduced from
IEEE Std 1003.2-1992, IEEE Standard Portable Operating
System Interface for Computer Environments (POSIX),
copyright 1992 by the Institute of Electrical and Electronics
Engineers, Inc.
.pp
The financial support of UUNET Communications Services is gratefully
acknowledged.
.)q
.sy echo -n >index
.oh 'Vi/Ex Reference''USD:13-%'
.eh 'USD:13-%''Vi/Ex Reference'
.bp 4
.SH 1 Description
.pp
.CO Vi
is a screen oriented text editor.
.CO Ex
is a line-oriented text editor.
.CO Ex
and
.CO vi
are different interfaces to the same program,
and it is possible to switch back and forth during an edit session.
.CO View
is the equivalent of using the
.b \-R
(read-only) option of
.CO vi .
.pp
This reference manual is the one provided with the
.EV nex nvi
versions of the
.EV ex vi
text editors.
.EV Nex nvi
are intended as bug-for-bug compatible replacements for the original
Fourth Berkeley Software Distribution (4BSD)
.EV ex vi
programs.
This reference manual is accompanied by a traditional-style manual page.
That manual page describes the functionality found in
.EV ex vi
in far less detail than the description here.
In addition, it describes the system interface to
.EV ex vi ,
e.g. command line options, session recovery, signals,
environmental variables, and similar things.
.pp
This reference is intended for users already familiar with
.EV ex vi .
Anyone else should almost certainly read a good tutorial on the
editor first.
If you are in an unfamiliar environment,
and you absolutely have to get work done immediately,
see the section entitled
.QB "Fast Startup"
in the manual page.
It is probably enough to get you started.
.pp
There are a few features in
.EV nex nvi
that are not found in historic versions of
.EV ex vi .
Some of the more interesting of those features are briefly described
in the next section, entitled
.QB "Additional Features" .
For the rest of this document,
.EV nex nvi
is used only when it is necessary to distinguish it from the historic
implementations of
.EV ex vi .
.pp
Future versions of this software will be periodically made available
by anonymous ftp, and can be retrieved from
.LI ftp.cs.berkeley.edu ,
in the directory
.LI ucb/4bsd .
.SH 1 "Additional Features in Nex/Nvi"
.pp
There are a few features in
.EV nex nvi
that are not found in historic versions of
.EV ex vi .
Some of the more interesting of these are as follows:
.IP "8-bit clean data, large lines, files"
.EV Nex nvi
will edit any format file.
Line lengths are limited by available memory,
and file sizes are limited by available disk space.
The
.CO vi
text input mode command
.CO <control-X>
can insert any possible character value into the text.
.IP "Background and foreground screens"
The
.CO bg
command backgrounds the current screen, and the
.CO fg
command foregrounds backgrounded screens.
The
.CO display
command can be used to list the background screens.
.IP "Command Editing"
You can enter a normal editing window on the collected commands that
you've entered on the
.CO vi
colon command-line,
and then modify and/or execute the commands.
See the
.OP cedit
edit option for more information.
.IP "Displays"
The
.CO display
command can be used to display the current buffers, the backgrounded
screens, and the tags stack.
.IP "Extended Regular Expressions"
The
.CO extended
option causes Regular Expressions to be interpreted as as Extended
Regular Expressions, (i.e. \fIegrep\fP(1) style Regular Expressions).
.IP "File Name Completion"
It is possible to do file name completion and file name displays when
entering commands on the
.CO vi
colon command-line.
See the
.OP filec
option for more information.
.IP "Infinite undo"
Changes made during an edit session may be rolled backward and forward.
A
.CO \&.
command immediately after a
.CO u
command continues either forward or backward depending on whether the
.CO u
command was an undo or a redo.
.IP "Left-right scrolling"
The
.CO leftright
option causes
.CO nvi
to do left-right screen scrolling, instead of the traditional
.CO vi
line wrapping.
.IP "Message Catalogs"
It is possible to display informational and error messages in different
languages by providing a catalog of messages.
See the
.OP msgcat
option and the file
.LI "catalog/README"
for more information.
.IP "Incrementing numbers"
The
.CO \&#
command increments or decrements the number referenced by the cursor.
.IP "Previous file"
The
.CO previous
command edits the previous file from the argument list.
.IP "Scripting languages"
The
.CO ":pe[rl] cmd" ,
.CO ":perld[o] cmd"
and
.CO ":tc[l] cmd"
commands execute Perl and Tcl/Tk commands, respectively,
on lines from the edit buffer.
See the
.QB "Scripting Languages"
section and the specific commands for more information.
.\".IP "Shell screens"
.\"The
.\".CO ":sc[ript] [file ...]"
.\"command runs a shell in the screen.
.\"Editing is unchanged, with the exception that a \fC<carriage-return>\fP
.\"enters the current line (stripped of any prompt) as input to the
.\"shell.
.IP "Split screens"
The
.CO Edit ,
.CO Ex ,
.CO Next ,
.CO Previous ,
.CO Tag
and
.CO Visual
(in
.CO vi
mode) commands divide the screen into multiple editing regions and
then perform their normal function in a new screen area.
The
.CO <control-W>
command rotates between the foreground screens.
The
.CO resize
command can be used to grow or shrink a particular screen.
.IP "Tag stacks"
Tags are now maintained in a stack.
The
.CO <control-T>
command returns to the previous tag location.
The
.CO tagpop
command returns to the most recent tag location by default, or,
optionally to a specific tag number in the tag stack,
or the most recent tag from a specified file.
The
.CO display
command can be used to list the tags stack.
The
.CO tagtop
command returns to the top of the tag stack.
.IP "Usage information"
The
.CO exusage
and
.CO viusage
commands provide usage information for all of the
.CO ex
and
.CO vi
commands by default, or, optionally, for a specific command or key.
.IP "Word search"
The
.CO <control-A>
command searches for the word referenced by the cursor.
.SH 1 "Startup Information"
.pp
.EV Ex vi
interprets one of two possible environmental variables and reads up to
three of five possible files during startup.
The variables and files are expected to contain
.CO ex
commands, not
.CO vi
commands.
In addition, they are interpreted
.i before
the file to be edited is read, and therefore many
.CO ex
commands may not be used.
Generally, any command that requires output to the screen or that
needs a file upon which to operate, will cause an error if included
in a startup file or environmental variable.
.pp
Because the
.CO ex
command set supported by
.EV nex nvi
is a superset of the command set supported by historical implementations of
.CO ex ,
.EV nex nvi
can use the startup files created for the historical implementations,
but the converse may not be true.
.pp
If the
.b \-s
(the historic \- option)
is specified, or if standard input is redirected from a file,
all environmental variables and startup files are ignored.
.pp
Otherwise, startup files and environmental variables are handled
in the following order:
.np
The file
.LI /etc/vi.exrc
is read,
as long as it is owned by root or the effective user ID of the user.
.np
The environmental variable
.LI NEXINIT
(or the variable
.LI EXINIT ,
if
.LI NEXINIT
is not set) is interpreted.
.np
If neither
.LI NEXINIT
or
.LI EXINIT
was set, and the
.LI HOME
environmental variable is set, the file
.LI $HOME/.nexrc
(or the file
.LI $HOME/.exrc ,
if
.LI $HOME/.nexrc
does not exist) is read,
as long as the effective user ID of the user is root or is the same as
the owner of the file.
.sp
When the $HOME directory is being used for both
.EV nex nvi
and an historic implementation of
.EV ex vi ,
a possible solution is to put
.EV nex nvi
specific commands in the
.LI \&.nexrc
file, along with a
.CO ":source $HOME/.exrc"
command to read in the commands common to both implementations.
.np
If the
.OP exrc
option was turned on by one of the previous startup information
sources, the file
.LI \&.nexrc
(or the file
.LI \&.exrc ,
if
.LI \&.nexrc
does not exist) is read, as long as the effective user ID of the user
is the same as the owner of the file.
.pp
No startup file is read if it is writable by anyone other than its owner.
.pp
It is not an error for any of the startup environmental variables or files
not to exist.
.pp
Once all environmental variables are interpreted,
and all startup files are read,
the first file to be edited is read in (or a temporary file is created).
Then, any commands specified using the
.b \-c
option are executed, in the context of that file.
.SH 1 "Recovery"
.pp
There is no recovery program for
.EV nex nvi ,
nor does
.EV nex nvi
run setuid.
Recovery files are created readable and writable by the owner only.
Users may recover any file which they can read,
and the superuser may recover any edit session.
.pp
Edit sessions are backed by files in the directory named by the
.OP recdir
option (the directory
.LI /var/tmp/vi.recover
by default), and are named
.QC vi.XXXXXX ,
where
.QC XXXXXX
is a number related to the process ID.
When a file is first modified,
a second recovery file containing an email message for the user is created,
and is named
.QC recover.XXXXXX ,
where, again,
.QC XXXXXX
is associated with the process ID.
Both files are removed at the end of a normal edit session,
but will remain if the edit session is abnormally terminated
or the user runs the
.CO ex
.CO preserve
command.
.pp
The
.OP recdir
option may be set in either the user's or system's startup information,
changing the recovery directory.
(Note, however, that if a memory based file system is used as the backup
directory, each system reboot will delete all of the recovery files!
The same caution applies to directories such as
.LI /tmp
which are cleared of their contents by a system reboot, or
.LI /usr/tmp
which is periodically cleared of old files on many systems.)
.pp
The recovery directory should be owned by root, or at least by a pseudo-user.
In addition, if directory
.QQ sticky-bit
semantics are available, the directory should have the sticky-bit
set so that files may only be removed by their owners.
The recovery directory must be read, write, and executable by any user,
i.e. mode 1777.
.pp
If the recovery directory does not exist,
.EV ex vi
will attempt to create it.
This can result in the recovery directory being owned by a normal user,
which means that that user will be able to remove other user's recovery
and backup files.
This is annoying, but is not a security issue as the user cannot
otherwise access or modify the files.
.pp
The recovery file has all of the necessary information in it to enable the
user to recover the edit session.
In addition, it has all of the necessary email headers for
.XR sendmail 8 .
When the system is rebooted, all of the files in
.LI /var/tmp/vi.recover
named
.QC recover.XXXXXX
should be sent to their owners, by email, using the
.b \-t
option of
.CO sendmail
(or a similar mechanism in other mailers).
If
.EV ex vi
receives a hangup (SIGHUP) signal, or the user executes the
.CO ex
.CO preserve
command,
.EV ex vi
will automatically email the recovery information to the user.
.pp
If your system does not have the
.CO sendmail
utility (or a mailer program which supports its interface)
the source file
.LI nvi/common/recover.c
will have to be modified to use your local mail delivery programs.
Note, if
.EV nex nvi
is changed to use another mailer,
it is important to remember that the owner of the file given to
the mailer is the
.EV nex nvi
user, so nothing in the file should be trusted as it may have been
modified in an effort to compromise the system.
.pp
Finally, the owner execute bit is set on backup files when they are
created, and unset when they are first modified, e.g. backup files
that have no associated email recovery file will have this bit set.
(There is also a small window where empty files can be created and
not yet have this bit set.
This is due to the method in which the files are created.)
Such files should be deleted when the system reboots.
.pp
A simple way to do this cleanup is to run the Bourne shell script
.CO recover ,
from your
.LI /etc/rc.local
(or other system startup) file.
The script should work with the historic Bourne shell,
a POSIX 1003.2 shell or the Korn shell.
The
.CO recover
script is installed as part of the
.EV nex nvi
installation process.
.pp
Consult the manual page for details on recovering preserved or
aborted editing sessions.
.SH 1 "Sizing the Screen"
.pp
The size of the screen can be set in a number of ways.
.EV Ex vi
takes the following steps until values are obtained for both the
number of rows and number of columns in the screen.
.np
If the environmental variable
.LI LINES
exists,
it is used to specify the number of rows in the screen.
.np
If the environmental variable
.LI COLUMNS
exists,
it is used to specify the number of columns in the screen.
.np
The TIOCGWINSZ
.XR ioctl 2
is attempted on the standard error file descriptor.
.np
The termcap entry (or terminfo entry on System V machines)
is checked for the
.QQ li
entry (rows) and the
.QQ co
entry (columns).
.np
The number of rows is set to 24, and the number of columns is set to 80.
.pp
If a window change size signal (SIGWINCH) is received,
the new window size is retrieved using the TIOCGWINSZ
.XR ioctl 2
call, and all other information is ignored.
.SH 1 "Character Display"
.pp
In both
.CO ex
and
.CO vi
printable characters as defined by
.XR isprint 3
are displayed using the local character set.
.pp
Non-printable characters, for which
.XR iscntrl 3
returns true, and which are less than octal \e040,
are displayed as the string
.QT ^<character> ,
where
.LI <character>
is the character that is the original character's value offset from the
.QT @
character.
For example, the octal character \e001 is displayed as
.QT ^A .
If
.XR iscntrl 3
returns true for the octal character \e177,
it is displayed as the string
.QT ^? .
All other characters are displayed as either hexadecimal values,
in the form
.QT "0x<high-halfbyte> ... 0x<low-halfbyte>" ,
or as octal values, in the form
.QT "\e<high-one-or-two-bits> ... \e<low-three-bits>" .
The display of unknown characters is based on the value of the
.OP octal
option.
.pp
In
.CO vi
command mode, the cursor is always positioned on the last column of
characters which take up more than one column on the screen.
In
.CO vi
text input mode, the cursor is positioned on the first column of
characters which take up more than one column on the screen.
.SH 1 "Multiple Screens"
.pp
.CO Nvi
supports multiple screens by dividing the window into regions.
It also supports stacks of screens by permitting the user to change
the set of screens that are currently displayed.
.pp
The
.CO Edit ,
.CO Ex ,
.CO Fg ,
.CO Next ,
.CO Previous ,
.CO Tag
and
.CO Visual
(in
.CO vi
mode)
commands divide the current screen into two regions of approximately
equal size and then perform their usual action in a new screen area.
If the cursor is in the lower half of the screen, the screen will split
up, i.e. the new screen will be above the old one.
If the cursor is in the upper half of the screen, the new screen will be
below the old one.
.pp
When more than one screen is editing a file, changes in any screen are
reflected in all other screens editing the same file.
Exiting a screen without saving any changes (or explicitly discarding
them) is permitted until the last screen editing the file is exited,
at which time the changes must be saved or discarded.
.pp
The
.CO resize
command permits resizing of individual screens.
Screens may be grown, shrunk or set to an absolute number of rows.
.pp
The
.CO ^W
command is used to switch between screens.
Each
.CO ^W
moves to the next lower screen in the window, or to the first screen
in the window if there are no lower screens.
.pp
The
.CO bg
command
.QQ backgrounds
the current screen.
The screen disappears from the window,
and the rows it occupied are taken over by a neighboring screen.
It is an error to attempt to background the only screen in the window.
.pp
The
.CO "display screens"
command displays the names of the files associated with the current
backgrounded screens in the window.
.pp
The
.CO "fg [file]"
command moves the specified screen from the list of backgrounded screens
to the foreground.
If no file argument is specified, the first screen on the list is
foregrounded.
By default,
foregrounding consists of backgrounding the current screen,
and replacing its space in the window with the foregrounded screen.
.pp
Capitalizing the first letter of the command, i.e.
.CO Fg ,
will foreground the backgrounded screen in a new screen instead of
swapping it with the current screen.
.pp
If the last foregrounded screen in the window is exited,
and there are backgrounded screens,
the first screen on the list of backgrounded screens takes over the window.
.SH 1 "Tags, Tag Stacks, and Cscope"
.pp
.CO Nvi
supports the historic
.CO vi
tag command
.CO <control-]> ,
and the historic
.CO ex
tag command
.CO tag .
These commands change the current file context to a new location,
based on information found in the
.LI tags
files.
If you are unfamiliar with these commands,
you should review their description in the
.CO ex
and
.CO vi
commands section of this manual.
For additional information on tags files,
see the discussion of the
.OP tags
edit option and the system
.XR ctags 1
manual page.
.pp
In addition,
.CO nvi
supports the notion of
.QQ "tags stacks" ,
using the
.CO <control-T>
command.
The
.CO <control-T>
command returns the user to the previous context, i.e.,
the last place from which a
.CO <control-]>
or
.CO "tag"
command was entered.
These three commands provide the basic functionality which allows you
to use
.CO vi
to review source code in a structured manner.
.pp
.CO Nvi
also provides two other basic
.CO ex
commands for tag support:
.CO tagpop
and
.CO tagtop .
The
.CO tagpop
command is identical to the
.CO <control-T>
command,
with the additional functionality that you may specify that modifications
to the current file are to be discarded.
This cannot be done using the
.CO <control-T>
command.
The
.CO tagtop
command discards all of the contexts that have been pushed onto the tag
stack, returning to the context from which the first
.CO <control-]>
or
.CO tag
command was entered.
.pp
The historic
.XR ctags 1
tags file format supports only a single location per tag,
normally the function declaration or structure or string definition.
More sophisticated source code tools often provide multiple locations
per tag, e.g.,
a list of the places from which a function is called or a string
definition is used.
An example of this functionality is the System V source code tool,
.CO cscope .
.sp
.CO Cscope
creates a database of information on source code files,
and supports a query language for that information as described in the
.XR cscope 1
manual page.
.CO Nvi
contains an interface to the
.CO cscope
query language which permits you to query
.CO cscope
and then sequentially step through the locations in the sources files which
.CO cscope
returns.
There are two
.CO nvi
commands which support this ability to step through multiple locations.
They are the
.CO ex
commands
.CO tagnext
and
.CO tagprev .
The
.CO tagnext
command moves to the next location for the current tag.
The
.CO tagprev
command moves to the previous location for the current tag.
(See the
.CO tagnext
and
.CO tagprev
command discussion in the
.CO ex
commands section of this manual for more information.)
At any time during this sequential walk,
you may use the
.CO <control-]> ,
.CO tag
or
.CO cscope
commands to move to a new tag context, and then use the
.CO <control-T>
or
.CO tagpop
commands to return and continue stepping through the locations for this
tag.
This is similar to the previous model of a simple tag stack,
except that each entry in the tag stack may have more than one file context
that is of interest.
.pp
Although there is no widely distributed version of
.XR ctags 1
that creates tags files with multiple locations per tag,
.CO nvi
has been written to understand the obvious extension to the historic
tags file format, i.e., more than a single line in the tags file with
the same initial tag name.
If you wish to extend your
.CO ctags 
implementation or other tool with which you build tags files,
this extension should be simple and will require no changes to
.CO nvi .
.pp
The
.CO nvi
and
.CO cscope
interface is based on the new
.CO ex
command
.CO cscope ,
which has five subcommands:
.CO add ,
.CO find ,
.CO help ,
.CO kill
and
.CO reset .
The subcommand
.CO find
itself has eight subcommands:
.CO \&c ,
.CO \&d ,
.CO \&e ,
.CO \&f ,
.CO \&g ,
.CO \&i ,
.CO \&s
and
.CO \&t .
.pp
.IP "cs[cope] a[dd] file"
The
.CO add
command attaches to the specified
.CO cscope
database.
The file name is expanded using the standard filename expansions.
If
.CO file
is a directory, the file
.QQ cscope.out
in that directory is used as the database.
.pp
After
.CO nvi
attaches to a new database,
all subsequent
.CO cscope
queries will be asked of that database.
The result of any single query is the collection of response to the query
from all of the attached databases.
.sp
If the
.QQ CSCOPE_DIRS
environmental variable is set when
.CO nvi
is run,
it is expected to be a <colon> or <blank>-separated list of
.CO cscope
databases or directories containing
.CO cscope
databases, to which the user wishes to attach.
.IP ":cs[cope] f[ind] c|d|e|f|g|i|s|t buffer|pattern"
The
.CO find
command is the
.CO cscope
query command for
.CO nvi .
For this command,
.CO nvi
queries all attached
.CO cscope
databases for the pattern.
If the pattern is a double-quote character followed by a valid buffer
name (e.g.,
.LI """<character>" ), 
then the contents of the named buffer are used as the pattern.
Otherwise, the pattern is a Regular Expression.
.sp
The
.CO find
command pushes the current location onto the tags stack,
and switches to the first location resulting from the query,
if the query returned at least one result.
.sp
File names returned by the
.CO cscope
query, if not absolute paths, are searched for relative to the directory
where the
.CO cscope
database is located.
In addition, if the file
.QQ cscope.tpath
appears in the same directory as the
.CO cscope
database,
it is expected to contain a colon-separated list of directory names
where files referenced by its associated
.CO cscope
database may be found.
.sp
The
.CO find
subcommand is one of the following:
.SS
.SP \&c
Find callers of the name.
.SP \&d
Find all function calls made from name.
.SP \&e
Find pattern.
.SP \&f
Find files with name as substring.
.SP \&g
Find definition of name.
.SP \&i
Find files #including name.
.SP \&s
Find all uses of name.
.SP \&t
Find assignments to name.
.SE
.IP ":cs[cope] h[elp] [command]"
List the
.CO cscope
commands,
or optionally list usage help for any single
.CO cscope
command.
.IP ":display c[onnections]"
Display the list of
.CO cscope
databases to which
.CO nvi
is currently connected.
.IP ":cs[cope] k[ill] #"
Disconnect from a specific
.CO cscope
database.
The connection number is the one displayed by the
.CO ex
.CO "display connections"
command.
.IP ":cs[cope] r[eset]"
Disconnect from all attached
.CO cscope
databases.
.pp
Cscope is not freely redistributable software,
but is fairly inexpensive and easily available.
To purchase a copy of
.CO cscope ,
see http://www.att.com/ssg/products/toolchest.html.
.SH 1 "Regular Expressions and Replacement Strings"
.pp
Regular expressions are used in line addresses,
as the first part of the
.CO ex
.CO substitute ,
.CO global ,
and
.CO v
commands, and in search patterns.
.pp
The regular expressions supported by
.EV ex vi
are, by default, the Basic Regular Expressions (BRE's) described in the
IEEE POSIX Standard 1003.2.
The
.OP extended
option causes all regular expressions to be interpreted as the Extended
Regular Expressions (ERE's) described by the same standard.
(See
.XR re_format 7
for more information.)
Generally speaking, BRE's are the Regular Expressions found in
.XR ed 1
and
.XR grep 1 ,
and ERE's are the Regular Expressions found in
.XR egrep 1 .
.pp
The following is not intended to provide a description of Regular
Expressions.
The information here only describes strings and characters which
have special meanings in the
.EV ex vi
version of RE's,
or options which change the meanings of characters that normally
have special meanings in RE's.
.np
An empty RE (e.g.
.QT //
or
.QT ??
is equivalent to the last RE used.
.np
The construct
.QT \e<
matches the beginning of a word.
.np
The construct
.QT \e>
matches the end of a word.
.np
The character
.QT ~
matches the replacement part of the last
.CO substitute
command.
.pp
When the
.OP magic
option is
.i not
set, the only characters with special meanings are a
.QT ^
character at the beginning of an RE, a
.QT $
character at the end of an RE, and the escaping character
.QT \e .
The characters
.QT \&. ,
.QT * ,
.QT [
and
.QT ~
are treated as ordinary characters unless preceded by a
.QT \e ;
when preceded by a
.QT \e
they regain their special meaning.
.pp
Replacement strings are the second part of a
.CO substitute
command.
.pp
The character
.QT &
(or
.QT \e&
if the
.OP magic
option is
.i not
set) in the replacement string stands for the text matched by the RE
that is being replaced.
The character
.QT ~
(or
.QT \e~
if the
.OP magic
option is
.i not
set) stands for the replacement part of the previous
.CO substitute
command.
It is only valid after a
.CO substitute
command has been performed.
.pp
The string
.QT \e# ,
where
.QT #
is an integer value from 1 to 9, stands for the text matched by
the portion of the RE enclosed in the
.QT # 'th
set of escaped parentheses, e.g.
.QT \e(
and
.QT \e) .
For example,
.QT "s/abc\e(.*\e)def/\e1/"
deletes the strings
.QT abc
and
.QT def
from the matched pattern.
.pp
The strings
.QT \el ,
.QT \eu ,
.QT \eL
and
.QT \eU
can be used to modify the case of elements in the replacement string.
The string
.QT \el
causes the next character to be converted to lowercase;
the string
.QT \eu
behaves similarly, but converts to uppercase
(e.g.
.LI s/abc/\eU&/
replaces the string
.LI abc
with
.LI ABC ).
The string
.QT \eL
causes characters up to the end of the string or the next occurrence
of the strings
.QT \ee
or
.QT \eE
to be converted to lowercase;
the string
.QT \eU
behaves similarly, but converts to uppercase.
.pp
If the entire replacement pattern is
.QT % ,
then the last replacement pattern is used again.
.pp
In
.CO vi ,
inserting a
.LI <control-M>
into the replacement string will cause
the matched line to be split into two lines at that point.
(The
.LI <control-M>
will be discarded.)
.SH 1 "Scripting Languages"
.pp
The
.CO nvi
editor currently supports two scripting languages, Tcl/Tk and Perl.
(Note that Perl4 isn't sufficient, and that the Perl5 used must be
version 5.002 or later.
See the
.QB "Building Nvi"
section for more information.
.pp
The scripting language interface is still being worked on,
therefore the following information is probably incomplete,
probably wrong in cases, and likely to change.
See the
.LI perl_api
and
.LI tcl_api
source directories for more information.
As a quick reference, the following function calls are provided for
both the Perl and Tcl interfaces.
The Perl interface uses a slightly different naming convention,
e.g. ``viFindScreen'' is named ``VI::FindScreen''.
.IP "viFindScreen file"
Return the
.LI "screenId" associated with
.LI file .
.IP "viAppendLine screenId lineNumber text"
Append
.LI text
as a new line after line number
.LI lineNumber ,
in the screen
.LI screenId .
.IP "viDelLine screenId lineNum"
Delete the line
.LI lineNumber
from the screen
.LI screenId .
.IP "viGetLine screenId lineNumber"
Return the line
.LI lineNumber
from the screen
.LI screenId .
.IP "viInsertLine screenId lineNumber text"
Insert
.LI text
as a new line before line number
.LI lineNumber
in the screen
.LI screenId .
.IP "viLastLine screenId"
Return the line number of the last line in the screen
.LI screenId .
.IP "viSetLine screenId lineNumber text"
Change the line
.LI lineNumber
in the screen
.LI screenId
to match the specified
.LI text .
.IP "viGetMark screenId mark"
Return the current line and column for the specified
.LI mark
from the screen
.LI screenId .
.IP "viSetMark screenId mark line column"
Set the specified
.LI mark
to be at line
.LI line ,
column
.LI column ,
in the screen
.LI screenId .
.IP "viGetCursor screenId"
Return the current line and column for the cursor in the screen
.LI screenId .
.IP "viSetCursor screenId line column"
Set the cursor in the screen
.LI screenId
to the specified
.LI line
and
.LI column .
.IP "viMsg screenId text"
Display the specified
.LI text
as a vi message in the screen
.LI screenId .
.IP "viNewScreen screenId [file]"
Create a new screen.
.IP "viEndScreen screenId"
Exit the screen 
.LI screenId .
.IP "viSwitchScreen screenId screenId"
Switch from the screen
.LI screenId
to the screen
.LI screenId .
.IP "viMapKey screenId key tclproc"
Map the specified
.LI key
in the screen
.LI screenId
to the Tcl procedure
.LI tclproc .
.IP "viUnmMapKey screenId key"
Unmap the specified
.LI key
in the screen
.LI screenId
.IP "viGetOpt screenId option"
Return the value of the specified
.LI option
from the screen
.LI screenId .
.IP "viSetOpt screenId command"
Set one or more options in the screen
.LI screenId .
.SH 1 "General Editor Description"
.pp
When
.CO ex
or
.CO vi
are executed,
the text of a file is read (or a temporary file is created),
and then all editing changes happen within the context of the
copy of the file.
.i "No changes affect the actual file until the file is written out" ,
either using a write command or another command which is affected by the
.OP autowrite
option.
.pp
All files are locked (using the
.XR flock 2
or
.XR fcntl 2
interfaces) during the edit session,
to avoid inadvertently making modifications to multiple copies of the file.
If a lock cannot be obtained for a file because it is locked by another
process, the edit session is read-only (as if the
.OP readonly
option or the
.b \-R
flag had been specified).
If a lock cannot be obtained for other reasons, the edit session will
continue, but the file status information
(see the
.CO <control-G>
command) will reflect this fact.
.pp
Both
.CO ex
and
.CO vi
are modeful editors, i.e. they have two modes,
.QQ command
mode and
.QQ "text input"
mode.
The former is intended to permit you to enter commands which modifies
already existing text.
The latter is intended to permit you to enter new text.
When
.CO ex
first starts running, it is in command mode, and usually displays a prompt
(see the
.OP prompt
option for more information).
The prompt is a single colon
.PQ :
character.
There are three commands that switch
.CO ex
into text input mode:
.CO append ,
.CO change
and
.CO insert .
Once in input mode, entering a line containing only a single period
.PQ \&.
ends text input mode and returns to command mode,
where the prompt is redisplayed.
.pp
When
.CO vi
first starts running, it is in command mode as well.
There are eleven commands that switch
.CO vi
into text input mode:
.CO A ,
.CO a ,
.CO C ,
.CO c ,
.CO I ,
.CO i ,
.CO O ,
.CO o ,
.CO R ,
.CO S
and
.CO s .
Once in input mode, entering an
.LI <escape>
character ends text input mode and returns to command mode.
.pp
.EV Ex vi
present three different interfaces to editing a file.
.CO Ex
presents a line oriented interface.
.CO Vi
presents a full screen display oriented interface,
also known as
.QQ "visual mode" .
In addition, there is a third mode,
.QQ "open mode" ,
which is line oriented,
but supports cursor movement and editing within the displayed line,
similarly to visual mode.
Open mode is not yet implemented in
.CO nvi .
.pp
The following words have special meanings in both the
.CO ex
and
.CO vi
command descriptions:
.KY <interrupt>
.IP <interrupt>
The interrupt character is used to interrupt the current operation.
Normally
.LI <control-C> ,
whatever character is set for the current terminal is used.
.KY "<literal-next>"
.IP "<literal-next>"
The literal next character is used to escape the subsequent character
from any special meaning.
This character is always
.LI <control-V> .
If the terminal is not set up to do XON/XOFF flow control,
then
.LI <control-Q>
is used to mean literal next as well.
.KY "current pathname"
.IP "current pathname"
The pathname of the file currently being edited by vi.
When the percent character
.PQ %
appears in a file name entered as part of an
.CO ex
command argument, it is replaced by the current pathname.
(The
.QT %
character can be escaped by preceding it with a backslash.)
.KY "alternate pathname"
.IP "alternate pathname"
The name of the last file name mentioned in an
.CO ex
command, or,
the previous current pathname if the last file mentioned
becomes the current file.
When the hash mark character
.PQ #
appears in a file name entered as part of an
.CO ex
command argument, it is replaced by the alternate pathname.
(The
.QT #
character can be escaped by preceding it with a backslash.)
.KY buffer
.IP buffer
One of a number of named areas for saving copies of text.
Commands that change or delete text can save the changed or deleted
text into a specific buffer, for later use, if the command allows
it (i.e. the
.CO ex
.CO change
command cannot save the changed text in a named buffer).
Buffers are named with a single character, preceded by a double quote,
e.g.
.LI """<character>"
in
.CO vi
and
without the double quote, e.g.
.LI <character> ,
in
.CO ex .
(The double quote isn't necessary for
.CO ex
because buffers names are denoted by their position in the command line.)
Historic implementations of
.EV ex vi
limited
.LI <character>
to the alphanumeric characters;
.EV nex nvi
permits the use of any character without another meaning in the position
where a buffer name is expected.
.sp
Buffers named by uppercase characters are the same as buffers
named by lowercase characters, e.g. the buffer named by the
English character
.QT A
is the same as the buffer named by the character
.QT a ,
with the exception that, if the buffer contents are being changed (as
with a text deletion or
.CO vi
.CO change
command), the text is
.i appended
to the buffer, instead of replacing the current contents.
.sp
The buffers named by the numeric characters (in English,
.QT 1
through
.QT 9 ),
are special.
If a region of text including characters from more than one line,
or a single line of text specified by using a line-oriented motion,
is changed or deleted in the file using the
.CO vi
.CO change
or
.CO delete
commands, a copy of the text is placed into the numeric buffer
.QT 1 ,
regardless of the user specifying another buffer in which to save it.
In addition, there are a few commands which, when used as a
.LI motion
with the
.CO vi
.CO change
and
.CO delete
commands,
.i always
copy the specified region of text into the numeric buffers regardless
of the region including characters from more than one line.
These commands are:
.sp
.ne 3v
.ft C
.TS
r r r r.
<control-A>	%	(	)
`<character>	/	?	N
n	{	}
.TE
.ft R
.sp
Before this copy is done, the previous contents of buffer
.QT 1
are moved into buffer
.QT 2 ,
.QT 2
into buffer
.QT 3 ,
and so on.
The contents of buffer
.QT 9
are discarded.
In
.CO vi ,
text may be explicitly stored into the numeric buffers.
In this case, the buffer rotation described above occurs before the
replacement of the buffer's contents.
The numeric buffers are only available in
.LI visual
and
.LI open
modes,
and are not accessible by
.CO ex
in any way, although changed and deleted text is still stored there
while in
.CO ex
mode.
.sp
When a
.CO vi
command synopsis shows both a
.LI [buffer]
and a
.LI [count] ,
they may be presented in any order.
.sp
Finally, all buffers are either
.QQ line
or
.QQ character
oriented.
All
.CO ex
commands which store text into buffers are line oriented.
Some
.CO vi
commands which store text into buffers are line oriented,
and some are character oriented; the description for each applicable
.CO vi
command notes whether text copied into buffers using the command
is line or character oriented.
In addition, the
.CO vi
command
.CO "display buffers"
displays the current orientation for each buffer.
Generally, the only importance attached to this orientation is that
if the buffer is subsequently inserted into the text, line oriented
buffers create new lines for each of the lines they contain, and
character oriented buffers create new lines for any lines
.i other
than the first and last lines they contain.
The first and last lines are inserted into the text at the current
cursor position, becoming part of the current line.
If there is more than one line in the buffer, however, the current
line itself will be split.
.KY "unnamed buffer"
.IP "unnamed buffer"
The unnamed buffer is a text storage area which is used by commands
that use or operate on a buffer when no buffer is specified by the user.
If the command stores text into a buffer,
the text is stored into the unnamed buffer even if a buffer is also
specified by the user.
It is not possible to append text to the unnamed buffer.
If text is appended to a named buffer,
the named buffer contains both the old and new text,
while the unnamed buffer contains only the new text.
There is no way to explicitly reference the unnamed buffer.
.sp
Historically, the contents of the unnamed buffer were discarded by many
different commands, even ones that didn't store text into it.
.EV Nex nvi
never discards the contents of the unnamed buffer until new text
replaces them.
.KY whitespace
.IP whitespace
The characters <tab> and <space>.
.KY "<carriage-return>"
.IP "<carriage-return>"
The character represented by an ASCII
.LI <control-M> .
This character is almost always treated identically to a
.LI <newline>
character, but differs in that it can be escaped into the file text or
into a command.
.KY <newline>
.IP <newline>
The character represented by an ASCII
.LI <control-J> .
This character is almost always treated identically to a
.LI <control-M>
character, but differs in that it cannot be escaped into the file text or
into a command.
.oh 'Vi/Ex Reference (Vi Commands)''USD:13-%'
.eh 'USD:13-%''Vi/Ex Reference (Vi Commands)'
.so vi.cmd.roff
.oh 'Vi/Ex Reference''USD:13-%'
.eh 'USD:13-%''Vi/Ex Reference'
.SH 1 "Ex Addressing"
.pp
Addressing in
.CO ex
(and when
.CO ex
commands are executed from
.CO vi )
relates to the current line.
In general, the current line is the last line affected by a command.
The exact effect on the current line is discussed under the description
of each command.
When the file contains no lines, the current line is zero.
.pp
Addresses are constructed by one or more of the following methods:
.np
The address
.QT \&.
refers to the current line.
.np
The address
.QT $
refers to the last line of the file.
.np
The address
.QT N ,
where
.LI N
is a positive number, refers to the N-th line of the file.
.np
The address
.QT '<character>
or
.QT `<character>
refers to the line marked with the name
.LI <character> .
(See the
.CO k
or
.CO m
commands for more information on how to mark lines.)
.np
A regular expression (RE) enclosed by slashes
.PQ /
is an address,
and it refers to the first line found by searching forward from the line
.i after
the current line toward the end of the file, and stopping at the
first line containing a string matching the RE.
(The trailing slash can be omitted at the end of the command line.)
.sp
If no RE is specified, i.e. the pattern is
.QT // ,
the last RE used in any command is used in the search.
.sp
If the
.OP extended
option is set, the RE is handled as an extended RE, not a basic RE.
If the
.OP wrapscan
option is set, the search wraps around to the beginning of the file
and continues up to and including the current line, so that the entire
file is searched.
.sp
The form
.QT \e/
is accepted for historic reasons,
and is identical to
.QT // .
.np
An RE enclosed in question marks
.PQ ?
addresses the first line found by searching backward from the line
.i preceding
the current line, toward the beginning of the file and stopping at the
first line containing a string matching the RE.
(The trailing question mark can be omitted at the end of a command line.)
.sp
If no RE is specified, i.e. the pattern is
.QT ?? ,
the last RE used in any command is used in the search.
.sp
If the
.OP extended
option is set, the RE is handled as an extended RE, not a basic RE.
If the
.OP wrapscan
option is set, the search  wraps around from the beginning of the file to
the end of the file and continues up to and including the current line,
so that the entire file is searched.
.sp
The form
.QT \e?
is accepted for historic reasons, and is identical to
.QT ?? .
.np
An address followed by a plus sign
.PQ +
or a minus sign
.PQ -
followed by a number is an offset address and refers to the address
plus (or minus) the indicated number of lines.
If the address is omitted, the addition or subtraction is done with
respect to the current line.
.np
An address of
.QT +
or
.QT \-
followed by a number is an offset from the current line.
For example,
.QT \-5
is the same as
.QT \&.\-5 .
.np
An address ending with
.QT +
or
.QT -
has 1 added to or subtracted from the address, respectively.
As a consequence of this rule and of the previous rule, the address
.QT \-
refers to the line preceding the current line.
Moreover, trailing
.QT +
and
.QT \-
characters have a cumulative effect.
For example,
.QT ++\-++
refers to the current line plus 3.
.np
A percent sign
.PQ %
is equivalent to the address range
.QT 1,$ .
.pp
.CO Ex
commands require zero, one, or two addresses.
It is an error to specify an address to a command which requires zero
addresses.
.pp
If the user provides more than the expected number of addresses to any
.CO ex
command, the first addresses specified are discarded.
For example,
.QT 1,2,3,5 print
prints lines 3 through 5, because the
.CO print
command only takes two addresses.
.pp
The addresses in a range are separated from each other by a comma
.PQ ,
or a semicolon
.PQ ; .
In the latter case, the current line
.PQ \&.
is set to the first address, and only then is the second address calculated.
This feature can be used to determine the starting line for forward and
backward searches (see rules (5) and (6) above).
The second address of any two-address sequence corresponds to a line that
follows, in the file, the line corresponding to the first address.
The first address must be less than or equal to the second address.
The first address must be greater than or equal to the first line of the
file, and the last address must be less than or equal to the last line
of the file.
.oh 'Vi/Ex Reference (Ex Commands)''USD:13-%'
.eh 'USD:13-%''Vi/Ex Reference (Ex Commands)'
.so ex.cmd.roff
.oh 'Vi/Ex Reference (Options)''USD:13-%'
.eh 'USD:13-%''Vi/Ex Reference (Options)'
.so set.opt.roff
.oh 'Vi/Ex Reference''USD:13-%'
.eh 'USD:13-%''Vi/Ex Reference'
.bp
.SH 1 Index
.lp
.2c +0.5i 3
.ta \n($luR
.nf
.so index.so
.fi
.\" Force the TOC to an odd page, in case it's a duplex printer.
.if o .bp
.bp 3
.1c
.ce 1
\fB\s+2Table of Contents\s0\fP
.sp
.xp
