ex.rm

早期freebsd实现

command apply here also.
If the file buffer is empty and there is no current name then
.I ex
treats this as an
.I edit
command.
.IP
Address `0' is legal for this command and causes the file to be read at
the beginning of the buffer.
Statistics are given as for the 
.I edit
command when the 
.I read
successfully terminates.
After a
.I read
the current line is the last line read.\(dd
.FS
\(dd Within
.I open
and
.I visual
the current line is set to the first line read rather than the last.
.FE
.LC
( \fB.\fR ) \fBread\fR  \fB!\fR\fIcommand\fR
.ZP
Reads the output of the command
.I command
into the buffer after the specified line.
This is not a variant form of the command, rather a read
specifying a
.I command
rather than a 
.I filename;
a blank or tab before the \fB!\fR is mandatory.
.LC
\fBrecover \fIfile\fR
.ZP
Recovers
.I file
from the system save area.
Used after a accidental hangup of the phone**
.FS
** The system saves a copy of the file you were editing only if you
have made changes to the file.
.FE
or a system crash** or
.I preserve
command.
Except when you use
.I preserve
you will be notified by mail when a file is saved.
.LC
\fBrewind\fR	abbr: \fBrew\fR
.ZP
The argument list is rewound, and the first file in the list is edited.
.LC
\fBrew!\fR
.ZP
Rewinds the argument list discarding any changes made to the current buffer.
.LC
\fBset\fR \fIparameter\fR
.ZP
With no arguments, prints those options whose values have been
changed from their defaults;
with parameter
.I all
it prints all of the option values.
.IP
Giving an option name followed by a `?'
causes the current value of that option to be printed.
The `?' is unnecessary unless the option is Boolean valued.
Boolean options are given values either by the form
`set \fIoption\fR' to turn them on or
`set no\fIoption\fR' to turn them off;
string and numeric options are assigned via the form
`set \fIoption\fR=value'.
.IP
More than one parameter may be given to 
.I set \|;
they are interpreted left-to-right.
.LC
\fBshell\fR	abbr: \fBsh\fR
.IP
A new shell is created.
When it terminates, editing resumes.
.LC
\fBsource\fR \fIfile\fR	abbr: \fBso\fR
.IP
Reads and executes commands from the specified file.
.I Source
commands may be nested.
.LC
( \fB.\fR , \fB.\fR ) \fBsubstitute\fR /\fIpat\fR\|/\fIrepl\fR\|/ \fIoptions\fR \fIcount\fR \fIflags\fR	abbr: \fBs\fR
.IP
On each specified line, the first instance of pattern
.I pat
is replaced by replacement pattern
.I repl.
If the
.I global
indicator option character `g'
appears, then all instances are substituted;
if the
.I confirm
indication character `c' appears,
then before each substitution the line to be substituted
is typed with the string to be substituted marked
with `\(ua' characters.
By typing an `y' one can cause the substitution to be performed,
any other input causes no change to take place.
After a
.I substitute
the current line is the last line substituted.
.IP
Lines may be split by substituting
new-line characters into them.
The newline in
.I repl
must be escaped by preceding it with a `\e'.
Other metacharacters available in
.I pat
and
.I repl
are described below.
.LC
.B stop
.ZP
Suspends the editor, returning control to the top level shell.
If
.I autowrite
is set and there are unsaved changes,
a write is done first unless the form
.B stop !
is used.
This commands is only available where supported by the teletype driver
and operating system.
.LC
( \fB.\fR , \fB.\fR ) \fBsubstitute\fR \fIoptions\fR \fIcount\fR \fIflags\fR	abbr: \fBs\fR
.ZP
If
.I pat
and
.I repl
are omitted, then the last substitution is repeated.
This is a synonym for the
.B &
command.
.LC
( \fB.\fR , \fB.\fR ) \fBt\fR \fIaddr\fR \fIflags\fR
.ZP
The
.I t
command is a synonym for 
.I copy .
.LC
\fBta\fR \fItag\fR
.ZP
The focus of editing switches to the location of
.I tag,
switching to a different line in the current file where it is defined,
or if necessary to another file.\(dd
.FS
\(dd If you have modified the current file before giving a
.I tag
command, you must write it out; giving another
.I tag
command, specifying no
.I tag
will reuse the previous tag.
.FE
.IP
The tags file is normally created by a program such as
.I ctags,
and consists of a number of lines with three fields separated by blanks
or tabs.  The first field gives the name of the tag,
the second the name of the file where the tag resides, and the third
gives an addressing form which can be used by the editor to find the tag;
this field is usually a contextual scan using `/\fIpat\fR/' to be immune
to minor changes in the file.  Such scans are always performed as if
.I nomagic
was set.
.PP
The tag names in the tags file must be sorted alphabetically.
.LC
\fBunabbreviate\fR \fIword\fP	abbr: \fBuna\fP
.ZP
Delete
.I word
from the list of abbreviations.
.LC
\fBundo\fR	abbr: \fBu\fR
.ZP
Reverses the changes made in the buffer by the last
buffer editing command.
Note that
.I global
commands are considered a single command for the purpose of 
.I undo
(as are
.I open
and
.I visual.)
Also, the commands
.I write
and
.I edit
which interact with the
file system cannot be undone.
.I Undo
is its own inverse.
.IP
.I Undo
always marks the previous value of the current line `\fB.\fR'
as `\'\''.
After an
.I undo
the current line is the first line restored
or the line before the first line deleted if no lines were restored.
For commands with more global effect
such as
.I global
and
.I visual
the current line regains it's pre-command value after an
.I undo.
.LC
\fBunmap\fR \fIlhs\fR
.ZP
The macro expansion associated by
.I map
for
.I lhs
is removed.
.LC
( 1 , $ ) \fBv\fR /\fIpat\fR\|/ \fIcmds\fR
.ZP
A synonym for the
.I global
command variant \fBg!\fR, running the specified \fIcmds\fR on each
line which does not match \fIpat\fR.
.LC
\fBversion\fR	abbr: \fBve\fR
.ZP
Prints the current version number of the editor
as well as the date the editor was last changed.
.LC
( \fB.\fR ) \fBvisual\fR \fItype\fR \fIcount\fR \fIflags\fR	abbr: \fBvi\fR
.ZP
Enters visual mode at the specified line.
.I Type
is optional and may be `\-' , `\(ua' or `\fB.\fR'
as in the
.I z
command to specify the placement of the specified line on the screen.
By default, if
.I type
is omitted, the specified line is placed as the first on the screen.
A
.I count
specifies an initial window size; the default is the value of the option
.I window.
See the document
.I "An Introduction to Display Editing with Vi"
for more details.
To exit this mode, type Q.
.LC
\fBvisual\fP file
.br
\fBvisual\fP +\fIn\fP file
.ZP
From visual mode,
this command is the same as edit.
.LC
( 1 , $ ) \fBwrite\fR \fIfile\fR	abbr: \fBw\fR
.ZP
Writes changes made back to \fIfile\fR, printing the number of lines and
characters written.
Normally \fIfile\fR is omitted and the text goes back where it came from.
If a \fIfile\fR is specified, then text will be written to that file.*
.FS
* The editor writes to a file only if it is
the current file and is
.I edited ,
if the file does not exist,
or if the file is actually a teletype,
.I /dev/tty,
.I /dev/null.
Otherwise, you must give the variant form \fBw!\fR to force the write.
.FE
If the file does not exist it is created.
The current file name is changed only if there is no current file
name; the current line is never changed.
.IP
If an error occurs while writing the current and
.I edited
file, the editor
considers that there has been ``No write since last change''
even if the buffer had not previously been modified.
.LC
( 1 , $ ) \fBwrite>>\fR \fIfile\fR	abbr: \fBw>>\fR
.ZP
Writes the buffer contents at the end of
an existing file.
.IP
.LC
\fBw!\fR \fIname\fR
.ZP
Overrides the checking of the normal \fIwrite\fR command,
and will write to any file which the system permits.
.LC
( 1 , $ ) \fBw\fR  \fB!\fR\fIcommand\fR
.ZP
Writes the specified lines into 
.I command.
Note the difference between \fBw!\fR which overrides checks and
\fBw\ \ !\fR which writes to a command.
.LC
\fBwq\fR \fIname\fR
.ZP
Like a \fIwrite\fR and then a \fIquit\fR command.
.LC
\fBwq!\fR \fIname\fR
.ZP
The variant overrides checking on the sensibility of the
.I write
command, as \fBw!\fR does.
.LC
\fBxit\fP \fIname\fR
.ZP
If any changes have been made and not written, writes the buffer out.
Then, in any case, quits.
.LC
( \fB.\fR , \fB.\fR )\|\fByank\fR \fIbuffer\fR \fIcount\fR	abbr: \fBya\fR
.ZP
Places the specified lines in the named
.I buffer,
for later retrieval via
.I put.
If no buffer name is specified, the lines go to a more volatile place;
see the \fIput\fR command description.
.LC
( \fB.+1\fR ) \fBz\fR \fIcount\fR
.ZP
Print the next \fIcount\fR lines, default \fIwindow\fR.
.LC
( \fB.\fR ) \fBz\fR \fItype\fR \fIcount\fR
.ZP
Prints a window of text with the specified line at the top.
If \fItype\fR is `\-' the line is placed at the bottom; a `\fB.\fR' causes
the line to be placed in the center.*
A count gives the number of lines to be displayed rather than
double the number specified by the \fIscroll\fR option.
On a \s-2CRT\s0 the screen is cleared before display begins unless a
count which is less than the screen size is given.
The current line is left at the last line printed.
.FS
* Forms `z=' and `z\(ua' also exist; `z=' places the current line in the
center, surrounds it with lines of `\-' characters and leaves the current
line at this line.  The form `z\(ua' prints the window before `z\-'
would.  The characters `+', `\(ua' and `\-' may be repeated for cumulative
effect.
On some v2 editors, no
.I type
may be given.
.FE
.LC
\fB!\fR \fIcommand\fR\fR
.ZP
The remainder of the line after the `!' character is sent to a shell
to be executed.
Within the text of
.I command
the characters 
`%' and `#' are expanded as in filenames and the character
`!' is replaced with the text of the previous command.
Thus, in particular,
`!!' repeats the last such shell escape.
If any such expansion is performed, the expanded line will be echoed.
The current line is unchanged by this command.
.IP
If there has been ``[No\ write]'' of the buffer contents since the last
change to the editing buffer, then a diagnostic will be printed
before the command is executed as a warning.
A single `!' is printed when the command completes.
.LC
( \fIaddr\fR , \fIaddr\fR ) \fB!\fR \fIcommand\fR\fR
.ZP
Takes the specified address range and supplies it as
standard input to
.I command;
the resulting output then replaces the input lines.
.LC
( $ ) \fB=\fR
.ZP
Prints the line number of the
addressed line.
The current line is unchanged.
.KS
.LC
( \fB.\fR , \fB.\fR ) \fB>\fR \fIcount\fR \fIflags\fR
.br
( \fB.\fR , \fB.\fR ) \fB<\fR \fIcount\fR \fIflags\fR
.IP
Perform intelligent shifting on the specified lines;
\fB<\fR shifts left and \fB>\fR shift right.
The quantity of shift is determined by the
.I shiftwidth
option and the repetition of the specification character.
Only white space (blanks and tabs) is shifted;
no non-white characters are discarded in a left-shift.
The current line becomes the last line which changed due to the
shifting.
.KE
.LC
\fB^D\fR
.ZP
An end-of-file from a terminal input scrolls through the file.
The
.I scroll
option specifies the size of the scroll, normally a half screen of text.
.LC
( \fB.\fR+1 , \fB.\fR+1 )
.br
( \fB.\fR+1 , \fB.\fR+1 ) |
.ZP
An address alone causes the addressed lines to be printed.
A blank line prints the next line in the file.
.LC
( \fB.\fR , \fB.\fR ) \fB&\fR \fIoptions\fR \fIcount\fR \fIflags\fR
.ZP
Repeats the previous
.I substitute
command.
.LC
( \fB.\fR , \fB.\fR ) \fB\s+2~\s0\fR \fIoptions\fR \fIcount\fR \fIflags\fR
.ZP
Replaces the previous regular expression with the previous
replacement pattern from a substitution.
.NH 1
Regular expressions and substitute replacement patterns
.NH 2
Regular expressions
.PP
A regular expression specifies a set of strings of characters.
A member of this set of strings is said to be
.I matched
by the regular expression.
.I Ex
remembers two previous regular expressions:
the previous regular expression used in a
.I substitute
command
and the previous regular expression used elsewhere
(referred to as the previous \fIscanning\fR regular expression.)
The previous regular expression
can always be referred to by a null \fIre\fR, e.g. `//' or `??'.
.NH 2
Magic and nomagic
.PP
The regular expressions allowed by
.I ex 
are constructed in one of two ways depending on the setting of
the
.I magic
option.
The
.I ex
and
.I vi
default setting of
.I magic
gives quick access to a powerful set of regular expression
metacharacters.
The disadvantage of
.I magic
is that the user must remember that these metacharacters are
.I magic
and precede them with the character `\e'
to use them as ``ordinary'' characters.
With
.I nomagic,
the default for
.I edit,
regular expressions are much simpler,
there being only two metacharacters.
The power of the other metacharacters is still available by preceding
the (now) ordinary character with a `\e'.
Note that `\e' is thus always a metacharacter.
.PP
The remainder of the discussion of regular expressions assumes
that
that the setting of this option is
.I magic.\(dg
.FS
\(dg To discern what is true with
.I nomagic
it suffices to remember that the only
special characters in this case will be `\(ua' at the beginning
of a regular expression,
`$' at the end of a regular expression,
and `\e'.
With
.I nomagic
the characters `\s+2~\s0' and `&' also lose their special meanings
related to the replacement pattern of a substitute.
.FE
.NH 2
Basic regular expression summary
.PP
The following basic constructs are used to construct
.I magic
mode regular expressions.
.IP \fIchar\fR 15
An ordinary character matches itself.
The characters `\(ua' at the beginning of a line,
`$' at the end of line,
`*' as any character other than the first,
`.', `\e', `[', and `\s+2~\s0' are not ordinary characters and
must be escaped (preceded) by `\e' to be treated as such.
.IP \fB\(ua\fR
At the beginning of a pattern
forces the match to succeed only at the beginning of a line.
.IP \fB$\fR
At the end of a regular expression forces the match to
succeed only at the end of the line.
.IP \&\fB.\fR
Matches any single character except
the new-line character.
.IP \fB\e<\fR
Forces the match
to occur only at the beginning of a ``variable'' or ``word'';
that is, either at the beginning of a line, or just before
a letter, digit, or underline and after a character not one of
these.
.IP \fB\e>\fR
Similar to `\e<', but matching the end of a ``variable''
or ``word'', i.e. either the end of the line or before character
which is neither a letter, nor a digit, nor the underline character.
.IP \fB[\fIstring\fR]\fR
Matches any (single) character in the class defined by
.I string.
Most characters in
.I string
define themselves.
A pair of characters separated by `\-' in
.I string
defines the set of characters collating between the specified lower and upper
bounds, thus `[a\-z]' as a regular expression matches
any (single) lower-case letter.
If the first character of
.I string
is an `\(ua' then the construct
matches those characters which it otherwise would not;
thus `[\(uaa\-z]' matches anything but a lower-case letter (and of course a
newline).
To place any of the characters