vi.ref

早期freebsd实现

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.\"     @(#)vi.ref	8.23 (Berkeley) 4/18/94
.\"
.Dd "April 18, 1994"
.Dt "EX/VI REFERENCE MANUAL" 1
.Os
.Sh NAME
.Nm ex, vi, view
.Nd text editors
.Sh DESCRIPTION
.Nm \&Vi
is a screen oriented text editor.
.Nm \&Ex
is a line-oriented text editor.
.Nm \&Ex
and
.Nm \&vi
are different interfaces to the same program,
and it is possible to switch back and forth during an edit session.
.Nm View
is the equivalent of using the
.Fl R
(read-only) option of
.Nm \&vi .
.Pp
This reference manual is the one provided with the
.Nm nex/nvi
versions of the
.Nm ex/vi
text editors.
.Nm Nex/nvi
are intended as bug-for-bug compatible replacements for the original
Fourth Berkeley Software Distribution (4BSD)
.Nm \&ex
and
.Nm \&vi
programs.
This reference manual is accompanied by a traditional-style manual page.
That manual page describes the functionality found in
.Nm ex/vi
in far less detail than the description here.
In addition, it describes the system interface to
.Nm ex/vi ,
e.g. command line options, environmental variables, and similar things.
.Pp
This reference is intended for users already familiar with
.Nm ex/vi .
Anyone else should almost certainly read a good tutorial on the
editor first.
If you're in an unfamiliar environment, and you absolutely have to
get work done immediately, see the section entitled FAST STARTUP
in the manual page.
It's probably enough to get you going.
.Pp
For the rest of this reference,
.Nm nex/nvi
is used only when it's necessary to distinguish it from the historic
implementations of
.Nm ex/vi .
.Sh ADDITIONAL FEATURES
There are a few features in
.Nm nex/nvi
that are not found in historic versions of
.Nm ex/vi .
A list of those features is as follows:
.Bl -tag -width indent
.It "8-bit clean data, large lines, files"
.Nm \&Nvi/nex
will edit any format file.
Line lengths are limited by available memory,
and file sizes are limited by available disk space.
The command
.Dq "^X[0-9A-Fa-f]* ,"
in input mode, will insert any legal character value into the text.
.It "Split screens"
The command
.Dq ":sp[lit] [file ...]"
splits the screen in vi mode.
The key
.Dq "^W"
switches between the foreground screens,
and the
.Dq ":resize count"
command can be used to grow or shrink a particular screen.
.It "Background and foreground screens"
The command
.Dq ":bg"
backgrounds the current screen,
and the command
.Dq ":fg [file]"
foregrounds the backgrounded screen
that is editing the specified file, or, by default, the first background
screen on the queue.
The command
.Dq ":di[splay] s[creens]"
lists the background screens.
.It "Shell screens"
The command
.Dq ":sc[ript] [file ...]"
runs a shell in the screen.
Editing is unchanged, with the exception that a <carriage-return>
enters the current line (stripped of any prompt) as input to the
shell.
.It "Tag stacks"
Tags are now maintained in a stack.
The command
.Dq "^T"
returns to the previous tag location.
The command
.Dq ":tagpop [number \| file]"
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 the specified file.
Use the command
.Dq ":di[splay] t[ags]"
to view the tags stack.
The command
.Dq ":tagtop"
returns to the top of the tag stack.
.It "New displays"
The command
.Dq ":di[splay] b[uffers] \| s[creens] \| t[ags]"
can be
used to display, respectively, the current cut buffers,
the backgrounded screens, and the tags stack.
.It "Infinite undo"
The changes made during an edit session may be rolled backward and
forward.
A '.' command immediately after a 'u' command continues either forward
or backward depending on whether the 'u' command was an undo or a redo.
.It "Usage information"
The command
.Dq ":exu[sage] [cmd]"
and
.Dq "viu[sage] [key]"
provide usage
information for all of the ex and vi commands by default, or, optionally,
for a specific command or key.
.It "Extended regular expressions"
The
.Dq ":set extended"
command treats search and other command regular
expressions as extended (egrep(1) style) regular expressions.
.It "Word search"
The command
.Dq "^A"
searches for the word referenced by the cursor.
.It "Number increment"
The command
.Dq "#"
increments the number referenced by the cursor.
.It "Previous file"
The command
.Dq ":prev[ious][!]"
edits the previous file from the
argument list.
.It "Left-Right scrolling"
The command
.Dq ":set leftright"
makes
.Nm nvi
do left-right screen scrolling, instead of the traditional
.Nm \&vi
line wrapping.
.Sh STARTUP INFORMATION
.Nm 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
.Nm \&ex
commands, not
.Nm \&vi
commands.
In addition, they are interpreted
.Em before
the file to be edited is read, and therefore many
.Nm \&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
First, the file
.Pa /etc/vi.exrc
is read.
Second, the environmental variable
.Ev NEXINIT
(or the variable
.Ev EXINIT ,
if
.Ev NEXINIT
isn't set) is interpreted.
Third, if neither
.Ev NEXINIT
or
.Ev EXINIT
was set, the file
.Pa $HOME/.nexrc
(or the file
.Pa $HOME/.exrc ,
if
.Pa $HOME/.nexrc
doesn't exist) is read.
Fourth, the file
.Pa .nexrc
(or the file
.Pa .exrc ,
if
.Pa .nexrc
doesn't exist) is read.
.Pp
Startup files will not be read if they are owned by anyone other
than the real user-id of the user running
.Nm \&vi ,
(or by
.Dq root
in the case of the file
.Pa /etc/vi.exrc )
or if they are writable by anyone other than the owner.
Home directory startup files (i.e.
.Pa $HOME/.nexrc
and
.Pa $HOME/.exrc )
will not be read if the
.Dq HOME
environmental variable is not set.
Local startup files (i.e.
.Pa .nexrc
and
.Pa .exrc )
will not be read if the
.Sy exrc
option is turned off in the
.Pa /etc/vi.exrc ,
.Pa $HOME/.nexrc ,
or
.Pa $HOME/.exrc
files, or in the
.Ev NEXINIT
or
.Ev EXINIT
environmental variables.
It is not an error for any of the startup environmental variables
or files not to exist.
.Pp
Because the
.Nm \&ex
command set supported by
.Nm nex/nvi
is a superset of the command set supported by most historical implementations
of
.Nm \&ex ,
.Nm nex/nvi
can use the startup files created for the historical implementations,
but the converse may not be true.
.Pp
Finally, if the
.Fl -s
(the historic
.Fl
option)
is specified, or if standard input is redirected from a file,
all environmental variables and startup files will be ignored.
.Sh CHARACTER DISPLAY
Printable characters are displayed using the local character set.
Non-printable characters, for which
.Xr iscntrl (3)
returns true, and which are less than octal \e076, are displayed
as the string
.Dq ^<character> ,
where <character> is the character that is the character's value
offset from the
.Dq \&@
character.
For example, the octal character \e001 is by default displayed as 
.Dq \&^A .
If
.Xr iscntrl (3)
returns true for the octal character \e177, it is displayed as the
string
.Dq ^? .
All other characters are displayed as either hexadecimal values,
in the form
.Dq "0x<high-halfbyte> ... 0x<low-halfbyte>" ,
or as octal values, in the form
.Dq "\<high-one-or-two-bits> ... \<low-three-bits> . 
The display of unknown characters is based on the value of the
.Sy octal
option.
.Pp
In
.Nm \&vi
command mode, the cursor is always position on the last column of
characters which take up more than one column on the screen.
In
.Nm \&vi
text insert mode, the cursor is positioned on the first column of
characters which take up more than one column on the screen.
.Sh SIZING THE SCREEN
The size of the screen can be set in a number of ways.
.Nm Ex/vi
takes the following steps until values are obtained for both the
number of rows and number of columns in the screen.
.sp
.Bl -enum -compact
.It
If the environmental variable
.Ev LINES
exists, it is used to specify the number of rows in the screen.
.It
If the environmental variable
.Ev COLUMNS
exists, it is used to specify the number of columns in the screen.
.It
The TIOCGWINSZ
.Xr ioctl 2
is attempted on the standard error file descriptor.
.It
The termcap entry is checked for the
.Dq \&li
entry (rows) and the
.Dq \&co
entry (columns).
.It
The number of rows is set to 24, and the number of columns is set
to 80.
.El
.Pp
If a window change size signal (SIGWINCH) is received,
the same steps are taken with the exception that the first two steps
are skipped.
.Sh REGULAR EXPRESSIONS AND REPLACEMENT STRINGS
Regular expressions are used in line addresses,
as the first part of
.Sy substitute ,
.Sy global ,
and
.Sy vglobal
commands,
and in search patterns.
.Pp
The regular expressions supported by
.Nm \&ex
and
.Nm \&vi
are, by default, the Basic Regular Expressions (BRE's) described in the
IEEE POSIX Standard 1003.2.
The
.Sy 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
.Xr ed 1
and
.Xr grep 1
style regular expressions, and ERE's are
.Xr egrep 1
style regular expressions.)
.Pp
There are some special strings and characters that can be used in
RE's:
.Bl -enum -compact
.It
An empty RE (e.g.
.Dq \&// )
is equivalent to the last RE used.
.It
The construct
.Dq \e<
matches the beginning of a word.
.It
The construct
.Dq \e>
matches the end of a word.
.It
The character
.Dq \&~
matches the replacement part of the last
.Sy substitute
command.
.El
.Pp
When the
.Sy magic
option is
.Em not
set,
the only characters with special meanings are
.Dq \&^
at the beginning of an RE,
.Dq \&$
at the end of an RE, and the escaping character
.Dq \&\e .
The characters
.Dq \&. ,
.Dq \&* ,
.Dq \&[ ,
and
.Dq \&~
are treated as ordinary characters unless preceded by a
.Dq \&\e ;
when preceded by a
.Dq \&\e
they regain their special meaning.
.Pp
Replacement strings are the second part of a
.Sy substitute
command.
.Pp
The character
.Dq \&&
(or
.Dq \e&
if the
.Sy magic
option is
.Em not
set) in the replacement string stands for the text matched by the RE
that's being replaced.
The character
.Dq \&~
(or
.Dq \e~
if the
.Sy magic
option is
.Em not
set) stands for the replacement part of the previous
.Sy substitute
command.
.Pp
The string
.Dq \e# ,
where
.Dq \&#
is an integer value from 1 to 9, stands for the text matched by
the portion of the RE enclosed in the #'th set of escaped parentheses,
e.g.
.Dq \e(
and
.Dq \e) .
For example, 
.Dq "s/abc\e(.*\e)def/\e1/"
deletes the strings
.Dq abc
and
.Dq def
from the matched pattern.
.Pp
The strings
.Dq \el ,
.Dq \eu ,
.Dq \eL ,
and
.Dq \eU
can be used to modify the case of elements in the replacement string.
The string
.Dq \el
causes the next character to be converted to lowercase; the string
.Dq \eu
behaves similarly, but converts to uppercase.
The strings
.Dq \eL
causes characters up to the end of the string or the next occurrence of
the strings
.Dq \ee
or
.Dq \eE
to be converted to lowercase; the string
.Dq \eU
behaves similarly, but converts to uppercase.
.Pp
In
.Nm \&vi ,
inserting a <control-M> into the replacement string will cause the
matched line to be split into two lines at that point.
.Sh RECOVERY
There is no recovery program for
.Nm nvi ,
nor does
.Nm nvi
run setuid.
Users may recover any file which they may read, and the superuser
may recover any edit session.
.Pp
Edit sessions are backed by files in
.Pa /var/tmp/vi.recover ,
and are named
.Dq "vi.XXXX" ,
where
.Dq "XXXX"
is a number related to the process id.
When a file is first modified, a second file, which contains an
email message for the user, is created, and is named
.Dq "recover.XXXX" ,
where, again,
.Dq "XXXX"
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 enters the ex/vi
.Dq "preserve"
command.
The use of the
.Pa /var/tmp
directory may be changed setting the
.Sy recdir
option in the user's or system startup information.
.Pp
The recovery directory should have the
.Dq "sticky-bit"
set so that only the owners of files may remove them.
If this is not possible on the system, then a pseudo-user should
own the recovery directory.
The recovery directory must be both read and write-able by
any user.
.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 sendmail.
When the system is rebooted, all of the files in
.Pa /var/tmp/vi.recover
named
.Dq "recover.XXXX"
should be sent by email,
using the
.Fl t
flag of sendmail (or a similar mechanism in other mailers).
A simple way to do this is to insert the following script into your
.Pa /etc/rc.local
(or other startup) file:
.ne 7v
.Bd -literal -offset indent -compact
# Recover nvi editor files.
virecovery=`echo /var/tmp/vi.recover/recover.*`
if [ "$virecovery" != "/var/tmp/vi.recover/recover.*" ]; then
	echo 'Recovering vi editor sessions'
	for i in $virecovery; do
		sendmail -t < $i
	done
fi
.Ed
.Pp
If
.Nm ex/vi
receives a hangup (SIGHUP) signal, it will email the recovery
information to the user itself.
.Pp
If you don't have the sendmail program on your system, the source file
.Pa nvi/recover.c
will have to be modified to use your local mail delivery programs.
.Sh SET OPTIONS
#include <set.opt.roff>