ex.rm

早期freebsd实现

`\(ua', `[', or `\-' in
.I string
you must escape them with a preceding `\e'.
.NH 2
Combining regular expression primitives
.PP
The concatenation of two regular expressions matches the leftmost and
then longest string
which can be divided with the first piece matching the first regular
expression and the second piece matching the second.
Any of the (single character matching) regular expressions mentioned
above may be followed by the character `*' to form a regular expression
which matches any number of adjacent occurrences (including 0) of characters
matched by the regular expression it follows.
.PP
The character `\s+2~\s0' may be used in a regular expression,
and matches the text which defined the replacement part
of the last
.I substitute
command.
A regular expression may be enclosed between the sequences
`\e(' and `\e)' with side effects in the
.I substitute
replacement patterns.
.NH 2
Substitute replacement patterns
.PP
The basic metacharacters for the replacement pattern are
`&' and `~'; these are
given as `\e&' and `\e~' when
.I nomagic
is set.
Each instance of `&' is replaced by the characters
which the regular expression matched.
The metacharacter `~' stands, in the replacement pattern,
for the defining text of the previous replacement pattern.
.PP
Other metasequences possible in the replacement pattern
are always introduced by the escaping character `\e'.
The sequence `\e\fIn\fR' is replaced by the text matched
by the \fIn\fR-th regular subexpression enclosed between
`\e(' and `\e)'.\(dg
.FS
\(dg When nested, parenthesized subexpressions are present,
\fIn\fR is determined by counting occurrences of `\e(' starting from the left.
.FE
The sequences `\eu' and `\el' cause the immediately following character in
the replacement to be converted to upper- or lower-case respectively
if this character is a letter.
The sequences `\eU' and `\eL' turn such conversion on, either until
`\eE' or `\ee' is encountered, or until the end of the replacement pattern.
.de LC
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.LP
.ta 3i
..
.NH 1
Option descriptions
.PP
.LC
\fBautoindent\fR, \fBai\fR	default: noai
.ZP
Can be used to ease the preparation of structured program text.
At the beginning of each
.I append ,
.I change
or
.I insert
command
or when a new line is
.I opened
or created by an
.I append ,
.I change ,
.I insert ,
or
.I substitute
operation within
.I open
or
.I visual
mode,
.I ex
looks at the line being appended after,
the first line changed
or the line inserted before and calculates the amount of white space
at the start of the line.
It then aligns the cursor at the level of indentation so determined.
.IP
If the user then types lines of text in,
they will continue to be justified at the displayed indenting level.
If more white space is typed at the beginning of a line,
the following line will start aligned with the first non-white character
of the previous line.
To back the cursor up to the preceding tab stop one can hit
\fB^D\fR.
The tab stops going backwards are defined at multiples of the
.I shiftwidth
option.
You
.I cannot
backspace over the indent,
except by sending an end-of-file with a \fB^D\fR.
.IP
Specially processed in this mode is a line with no characters added
to it, which turns into a completely blank line (the white
space provided for the
.I autoindent
is discarded.)
Also specially processed in this mode are lines beginning with
an `\(ua' and immediately followed by a \fB^D\fR.
This causes the input to be repositioned at the beginning of the line,
but retaining the previous indent for the next line.
Similarly, a `0' followed by a \fB^D\fR
repositions at the beginning but without
retaining the previous indent.
.IP
.I Autoindent
doesn't happen in
.I global
commands or when the input is not a terminal.
.LC
\fBautoprint\fR, \fBap\fR	default: ap
.ZP
Causes the current line to be printed after each
.I delete ,
.I copy ,
.I join ,
.I move ,
.I substitute ,
.I t ,
.I undo
or
shift command.
This has the same effect as supplying a trailing `p'
to each such command.
.I Autoprint
is suppressed in globals,
and only applies to the last of many commands on a line.
.LC
\fBautowrite\fR, \fBaw\fR	default: noaw
.ZP
Causes the contents of the buffer to be written to the current file
if you have modified it and give a
.I next,
.I rewind,
.I stop,
.I tag,
or
.I !
command, or a \fB^\(ua\fR (switch files) or \fB^]\fR (tag goto) command
in
.I visual.
Note, that the
.I edit
and
.I ex
commands do
.B not
autowrite.
In each case, there is an equivalent way of switching when autowrite
is set to avoid the
.I autowrite
(\fIedit\fR
for
.I next ,
.I rewind!
for .I rewind ,
.I stop!
for
.I stop ,
.I tag!
for
.I tag ,
.I shell
for
.I ! ,
and
\fB:e\ #\fR and a \fB:ta!\fR command from within
.I visual).
.LC
\fBbeautify\fR, \fBbf\fR	default: nobeautify
.ZP
Causes all control characters except tab, newline and form-feed
to be discarded from the input.
A complaint is registered the first time a
backspace character is discarded.
.I Beautify
does not apply to command input.
.LC
\fBdirectory\fR, \fBdir\fR	default: dir=/tmp
.ZP
Specifies the directory in which
.I ex
places its buffer file.
If this directory in not
writable, then the editor will exit abruptly when it fails to be
able to create its buffer there.
.LC
\fBedcompatible\fR	default: noedcompatible
.ZP
Causes the presence of absence of
.B g
and
.B c
suffixes on substitute commands to be remembered, and to be toggled
by repeating the suffices.  The suffix
.B r
makes the substitution be as in the
.I ~
command, instead of like
.I &.
.LC
\fBerrorbells\fR, \fBeb\fR	default: noeb
.ZP
Error messages are preceded by a bell.*
.FS
* Bell ringing in
.I open
and
.I visual
on errors is not suppressed by setting
.I noeb.
.FE
If possible the editor always places the error message in a standout mode of the
terminal (such as inverse video) instead of ringing the bell.
.LC
\fBhardtabs\fR, \fBht\fR	default: ht=8
.ZP
Gives the boundaries on which terminal hardware tabs are set (or
on which the system expands tabs).
.LC
\fBignorecase\fR, \fBic\fR	default: noic
.ZP
All upper case characters in the text are mapped to lower case in regular
expression matching.
In addition, all upper case characters in regular expressions are mapped
to lower case except in character class specifications.
.LC
\fBlisp\fR	default: nolisp
.ZP
\fIAutoindent\fR indents appropriately for
.I lisp
code, and the \fB( ) { } [[\fR and \fB]]\fR commands in
.I open
and
.I visual
are modified to have meaning for \fIlisp\fR.
.LC
\fBlist\fR	default: nolist
.ZP
All printed lines will be displayed (more) unambiguously,
showing tabs and end-of-lines as in the
.I list
command.
.LC
\fBmagic\fR	default: magic for \fIex\fR and \fIvi\fR\(dg
.FS
\(dg \fINomagic\fR for \fIedit\fR.
.FE
.ZP
If
.I nomagic
is set, the number of regular expression metacharacters is greatly reduced,
with only `\(ua' and `$' having special effects.
In addition the metacharacters
`~'
and
`&'
of the replacement pattern are treated as normal characters.
All the normal metacharacters may be made
.I magic
when
.I nomagic
is set by preceding them with a `\e'.
.LC
\fBmesg\fR	default: mesg
.ZP
Causes write permission to be turned off to the terminal
while you are in visual mode, if
.I nomesg
is set.
.LC
\fBmodeline\fR	default: nomodeline
.ZP
If
.I modeline
is set, then the first 5 lines and the last five lines of the file
will be checked for ex command lines and the comands issued.
To be recognized as a command line, the line must have the string
.B ex:
or
.B vi:
preceeded by a tab or a space.  This string may be anywhere in the
line and anything after the 
.I :
is interpeted as editor commands.  This option defaults to off because
of unexpected behavior when editting files such as
.I /etc/passwd.
.LC
\fBnumber, nu\fR	default: nonumber
.ZP
Causes all output lines to be printed with their
line numbers.
In addition each input line will be prompted for by supplying the line number
it will have.
.LC
\fBopen\fR	default: open
.ZP
If \fInoopen\fR, the commands
.I open
and
.I visual
are not permitted.
This is set for
.I edit
to prevent confusion resulting from accidental entry to 
open or visual mode.
.LC
\fBoptimize, opt\fR	default: optimize
.ZP
Throughput of text is expedited by setting the terminal
to not do automatic carriage returns
when printing more than one (logical) line of output,
greatly speeding output on terminals without addressable
cursors when text with leading white space is printed.
.LC
\fBparagraphs,\ para\fR	default: para=IPLPPPQPP\0LIbp
.ZP
Specifies the paragraphs for the \fB{\fR and \fB}\fR operations in
.I open
and 
.I visual.
The pairs of characters in the option's value are the names
of the macros which start paragraphs.
.LC
\fBprompt\fR	default: prompt
.ZP
Command mode input is prompted for with a `:'.
.LC
\fBredraw\fR	default: noredraw
.ZP
The editor simulates (using great amounts of output), an intelligent
terminal on a dumb terminal (e.g. during insertions in
.I visual
the characters to the right of the cursor position are refreshed
as each input character is typed.)
Useful only at very high speed.
.LC
\fBremap\fP	default: remap
.ZP
If on, macros are repeatedly tried until they are unchanged.
For example, if
.B o
is mapped to
.B O ,
and
.B O
is mapped to
.B I ,
then if
.I remap
is set,
.B o
will map to
.B I ,
but if
.I noremap
is set, it will map to
.B O .
.LC
\fBreport\fR	default: report=5\(dg
.FS
\(dg 2 for \fIedit\fR.
.FE
.ZP
Specifies a threshold for feedback from commands.
Any command which modifies more than the specified number of lines
will provide feedback as to the scope of its changes.
For commands such as
.I global ,
.I open ,
.I undo ,
and
.I visual
which have potentially more far reaching scope,
the net change in the number of lines in the buffer is
presented at the end of the command, subject to this same threshold.
Thus notification is suppressed during a
.I global
command on the individual commands performed.
.LC
\fBscroll\fR	default: scroll=\(12 window
.ZP
Determines the number of logical lines scrolled when an end-of-file
is received from a terminal input in command mode,
and the number of lines printed by a command mode
.I z
command (double the value of
.I scroll ).
.LC
\fBsections\fR	default: sections=SHNHH\0HU
.ZP
Specifies the section macros for the \fB[[\fR and \fB]]\fR operations
in
.I open
and
.I visual.
The pairs of characters in the options's value are the names
of the macros which start paragraphs.
.LC
\fBshell\fR, \fBsh\fR	default: sh=/bin/sh
.ZP
Gives the path name of the shell forked for 
the shell escape command `!', and by the
.I shell
command.
The default is taken from SHELL in the environment, if present.
.LC
\fBshiftwidth\fR, \fBsw\fR	default: sw=8
.ZP
Gives the width a software tab stop,
used in reverse tabbing with \fB^D\fR when using
.I autoindent
to append text,
and by the shift commands.
.LC
\fBshowmatch, sm\fR	default: nosm
.ZP
In
.I open
and
.I visual
mode, when a \fB)\fR or \fB}\fR is typed, move the cursor to the matching
\fB(\fR or \fB{\fR for one second if this matching character is on the
screen.  Extremely useful with
.I lisp.
.LC
\fBslowopen, slow\fR	terminal dependent
.ZP
Affects the display algorithm used in
.I visual
mode, holding off display updating during input of new text to improve
throughput when the terminal in use is both slow and unintelligent.
See
.I "An Introduction to Display Editing with Vi"
for more details.
.LC
\fBtabstop,\ ts\fR	default: ts=8
.ZP
The editor expands tabs in the input file to be on
.I tabstop
boundaries for the purposes of display.
.LC
\fBtaglength,\ tl\fR	default: tl=0
.ZP
Tags are not significant beyond this many characters.
A value of zero (the default) means that all characters are significant.
.LC
\fBtags\fR	default: tags=tags /usr/lib/tags
.ZP
A path of files to be used as tag files for the
.I tag
command.
A requested tag is searched for in the specified files, sequentially.
By default, files called
.B tags
are searched for in the current directory and in /usr/lib
(a master file for the entire system).
.LC
\fBterm\fR	from environment TERM
.ZP
The terminal type of the output device.
.LC
\fBterse\fR	default: noterse
.ZP
Shorter error diagnostics are produced for the experienced user.
.LC
\fBwarn\fR	default: warn
.ZP
Warn if there has been `[No write since last change]' before a `!'
command escape.
.LC
\fBwindow\fR	default: window=speed dependent
.ZP
The number of lines in a text window in the
.I visual
command.
The default is 8 at slow speeds (600 baud or less),
16 at medium speed (1200 baud),
and the full screen (minus one line) at higher speeds.
.LC
\fBw300,\ w1200\, w9600\fR
.ZP
These are not true options but set
.B window
only if the speed is slow (300), medium (1200), or high (9600),
respectively.
They are suitable for an EXINIT
and make it easy to change the 8/16/full screen rule.
.LC
\fBwrapscan\fR, \fBws\fR	default: ws
.ZP
Searches using the regular expressions in addressing
will wrap around past the end of the file.
.LC
\fBwrapmargin\fR, \fBwm\fR	default: wm=0
.ZP
Defines a margin for automatic wrapover of text during input in
.I open
and
.I visual
modes.  See
.I "An Introduction to Text Editing with Vi"
for details.
.LC
\fBwriteany\fR, \fBwa\fR	default: nowa
.IP
Inhibit the checks normally made before
.I write
commands, allowing a write to any file which the system protection
mechanism will allow.
.NH 1
Limitations
.PP
Editor limits that the user is likely to encounter are as follows:
1024 characters per line,
256 characters per global command list,
128 characters per file name,
128 characters in the previous inserted and deleted text in
.I open
or
.I visual,
100 characters in a shell escape command,
63 characters in a string valued option,
and 30 characters in a tag name, and
a limit of 250000 lines in the file is silently enforced.
.PP
The
.I visual
implementation limits the number of macros defined with map to
32, and the total number of characters in macros to be less than 512.
.LP
.LP
.I Acknowledgments.
Chuck Haley contributed greatly to the early development of
.I ex.
Bruce Englar encouraged the redesign which led to
.I ex
version 1.
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 the
editor work on a large number of terminals and Unix systems.