ex.html

unix 下的C开发手册,还用详细的例程。

<p>
If the
<i>file</i>
is preceded by
"!",
the program named in the
<i>SHELL</i>
environment variable will be
invoked with
<i>file</i>
as its second argument, and the specified
lines will be passed as standard input to the command.
The
<b>!</b>
in this usage must be separated from the
<b>w</b>
command by at least one
blank
character.
The special meaning of the
<b>!</b>
can be
overridden by escaping it with a backslash character.
This command is affected by the editor options
<b>writeany</b>
and
<b>readonly</b>.
<p>
The command
<b>wq</b>
is equivalent to a
<b>w</b>
followed
by a
<b>q</b>;
<b>wq!</b>
is equivalent to
<b>w!</b>
followed by
<b>q</b>.
If the current buffer has no pathname associated with it, the
<b>write</b>
command will fail.
<h5><a name = "tag_001_014_598_040">&nbsp;</a>Write and Exit</h5>
<i>Synopsis</i>:   
<b>[</b><i>range</i><b>] </b>x<b>[</b>it<b>][</b>!<b>] [</b><i>file</i><b>]</b>
<p>
Perform a
<b>write</b>
command
if any changes have been made to the current buffer
since the last write to any file.
The
<i>range</i>
defaults to the entire file.
<p>
Unless the command fails because an attempt to
write lines to a file did not succeed, the
<i>ex</i>
utility will exit after an
<b>x</b>
command.
This command is affected by the editor options
<b>writeany</b>
and
<b>readonly</b>.
<h5><a name = "tag_001_014_598_041">&nbsp;</a>Yank</h5>
<i>Synopsis</i>:   
<b>[</b><i>range</i><b>] </b>ya<b>[</b>nk<b>] [</b><i>buffer</i><b>] [</b><i>count</i><b>]</b>
<p>
Place the specified lines in the named buffer.
If no buffer is specified, the unnamed buffer will be used
(where the most recently deleted or yanked text is placed by default).
<h5><a name = "tag_001_014_598_042">&nbsp;</a>Adjust Window</h5>
<i>Synopsis</i>:   
<b>[</b><i>line</i><b>] </b>z <b>[</b><i>type</i><b>] [</b><i>count</i><b>] [</b><i>flags</i><b>]</b>
<p>
If
<i>type</i>
is omitted, then
<i>count</i>
lines following the specified line
(<i>line</i>)
will be written.
The default for
<i>count</i>
is the value of the editor option
<b>window</b>.
The
<i>type</i>
argument will change the position at which
<i>line</i>
will be written on the screen by affecting the number of
lines written before and after
<i>line</i>.
<p>
If
<i>type</i>
is specified, it will be one of the following:
<dl compact>

<dt><b>-</b><dd>Place
<i>line</i>
at the bottom of the screen.

<dt><b>+</b><dd>Place
<i>line</i>
at the top of the screen.

<dt><b>.</b><dd>Place
<i>line</i>
in the middle.

<dt><b>^</b><dd>Write out
<i>count</i>
lines starting
<i>count</i>*2
lines before the addressed line; the net effect of this will be that a
<b>z^</b>
command following another
<b>z</b>
command writes the previous page.

<dt><b>=</b><dd>Centre the addressed line
on the screen with a line of hyphens written
immediately before and after it.
The number of preceding and
following lines of text written will be reduced to account for
these lines of hyphens.

</dl>
<p>
In all cases the
current line indicator will be set to
the last line written, with the exception of the
"="
type, which causes the current line indicator to be set to
that addressed in the command.
<h5><a name = "tag_001_014_598_043">&nbsp;</a>Escape</h5>
<i>Synopsis</i>:   
! <i>command</i>
<br>
<i>Synopsis</i>:   
<b>[</b><i>range</i><b>]</b>! <i>command</i>
<p>
Pass the remainder of the line after the
<b>!</b>
character to the program named in the
<i>SHELL</i>
environment variable for execution.
A warning will be issued if the buffer has been changed since the last write.
A single
<b>!</b>
character will be written when the command completes.
The current line position will not be affected.
<p>
Within the text of
<i>command</i>,
<b>%</b>
and
<b>#</b>
will be expanded as pathnames (the current and alternative pathnames,
respectively),
and
<b>!</b>
will be replaced with the text of the previous
<b>!</b>
command.
(Thus,
<b>!!</b>
will repeat the previous
<b>!</b>
command.)
If any such expansion is done, the expanded line will be echoed.
<p>
The special meanings of
<b>%</b>,
<b>#</b>
and
<b>!</b>
can be overridden by
escaping them with a backslash character.
This command is affected by the editor options
<b>autowrite</b>
and
<b>writeany</b>;
see
<xref href=exedops><a href="#tag_001_014_598_052">
Edit Options in ex
</a></xref>
for details.
<p>
In the second form of the
<b>!</b>
command, the remainder of the line after the
<b>!</b>
will be passed to the
program named in the
<i>SHELL</i>
environment variable, as described above.
The specified lines
will be provided to the program
as standard input;
the resulting output will replace the specified lines.
<h5><a name = "tag_001_014_598_044">&nbsp;</a>Shift Left</h5>
<i>Synopsis</i>:   
<b>[</b><i>range</i><b>]</b> &lt; <b>[</b><i>count</i><b>] [</b><i>flags</i><b>]</b>
<p>
Shift the specified lines to the left;
the number of character positions
to be shifted will be determined by the editor option
<b>shiftwidth</b>.
Only leading
blank characters
will be lost in shifting; other characters
will not be affected.
The current line indicator will be set to the last line changed.
<h5><a name = "tag_001_014_598_045">&nbsp;</a>Shift Right</h5>
<i>Synopsis</i>:   
<b>[</b><i>range</i><b>]</b> &gt; <b>[</b><i>count</i><b>] [</b><i>flags</i><b>]</b>
<p>
Shift the specified lines to the right, by inserting
blank characters,
using
tab characters
where possible, as determined by the editor option
<b>shiftwidth</b>.
Empty lines will not be changed.
The current line indicator will be set to the last line changed.
<h5><a name = "tag_001_014_598_046">&nbsp;</a>Resubstitute</h5>
<i>Synopsis</i>:   
<b>[</b><i>range</i><b>] </b>&amp; <b>[</b><i>options</i><b>] [</b><i>count</i><b>] [</b><i>flags</i><b>]</b>
<br>
<i>Synopsis</i>:   
<b>[</b><i>range</i><b>] </b>s<b>[</b>ubstitute<b>] [</b><i>options</i><b>] [</b><i>count</i><b>] [</b><i>flags</i><b>]</b>
<br>
<i>Synopsis</i>:   
<b>[</b><i>range</i><b>] ~ </b> <b>[</b><i>options</i><b>] [</b><i>count</i><b>] [</b><i>flags</i><b>]</b>
<p>
Repeat the previous substitute command, as if &amp; were replaced by the
previous:
<pre>
<code>
s/<i>pattern</i>/<i>repl</i>/
</code>
</pre>
command.
The same effect can obtained by omitting the:
<pre>
<code>
/<i>pattern</i>/<i>repl</i>/
</code>
</pre>
string in the
<b>substitute</b>
command.
The version of the command using tilde will be the same as &amp; and
<b>s</b>,
but the
<i>pattern</i>
used will be the last regular expression used in any command,
not necessarily the one used in the last substitute command.
For example, in the sequence:
<pre>
<code>
s/red/blue/
/green
~
</code>
</pre>
the "~" is equivalent to:
<pre>
<code>
s/green/blue/
</code>
</pre>
<h5><a name = "tag_001_014_598_047">&nbsp;</a>Scroll</h5>
<xref type="5" name="scroll"></xref>
<i>Synopsis</i>:   
<i>eof</i>
<p>
Write the next
<i>n</i>
lines, where
<i>n</i>
is the value of the editor option
<b>scroll</b>.
The command is invoked with the
<b>eof</b>
character (see the description of the
<i><a href="stty.html">stty</a></i>
<b>eof</b>
character).
The current line indicator will be set to the last line written.
This command need not be supported on block-mode terminals.
<h5><a name = "tag_001_014_598_048">&nbsp;</a>Write Line Number</h5>
<i>Synopsis</i>:   
<b>[</b><i>line</i><b>] </b>= <b>[</b><i>flags</i><b>]</b>
<p>
Write the line number of the specified line (default last line).
The current line position will not be affected.
<h5><a name = "tag_001_014_598_049">&nbsp;</a>Execute</h5>
<i>Synopsis</i>:   
 @ <i>buffer</i>
<br>
<i>Synopsis</i>:   
* <i>buffer</i>
<p>
Execute each line of the named buffer as an
<i>ex</i>
command.
If no buffer is specified or is specified as "@" or "*",
the last buffer executed will be used.
If there is no last buffer,
an error occurs.
<h5><a name = "tag_001_014_598_050">&nbsp;</a>Regular Expressions in ex</h5>
<xref type="5" name="exre"></xref>
The
<i>ex</i>
utility supports the basic regular expressions described in
the <b>XBD</b> specification, <a href="../xbd/re.html#tag_007_003"><b>Basic Regular Expressions</b>&nbsp;</a> .
A null RE
(//)
is equivalent to the last RE encountered.
<p>
Regular expressions can be used in addresses to specify lines and, in some
commands (for example, the
<b>substitute</b>
command), to specify portions of a line to be substituted.
<p>
The following constructs can be used to enhance the
basic regular expressions:
<dl compact>

<dt>\&lt;<dd>Match the beginning of a
<i>word</i>.
(See the definition of
<i>word</i>
at the beginning of
<xref href=excmd><a href="#tag_001_014_598_002">
Command Descriptions in ex
</a></xref>.)

<dt>\&gt;<dd>Match the end of a
<i>word</i>.

<dt>~<dd>Match the replacement part of the last
<b>substitute</b>
command.
The tilde
(~)
character can be escaped in a regular expression to become
a normal character with no special meaning.

</dl>
<p>
When
the editor option
<b>nomagic</b>
is set, the only characters with special meanings are "^"
at the beginning of a pattern, "$" at the end of a pattern, and "\".
The characters ".", "*", "[" and "~" are treated as ordinary characters
unless preceded by a "\";
when preceded by a "\" they regain their special meaning.
<h5><a name = "tag_001_014_598_051">&nbsp;</a>Replacement Strings in ex</h5>
<xref type="5" name="exrep"></xref>
The character &amp;
(\&amp; if the editor option
<b>nomagic</b>
is set)
in the replacement string will stand for the
text matched by the pattern to be replaced.
The character
~ (\~
if
<b>nomagic</b>
is set)
will be replaced by the replacement part of the
previous substitute command.
The sequence
\<i>n</i>
where
<i>n</i>
is an integer, will be replaced by
the text matched by the pattern enclosed in the
<i>n</i>th
set of parentheses
\(
and
\).
<p>
The strings
\l,
\u,
\L
and
\U
can be used to modify the case of elements in
the replacement string (using the
\&amp;
or
\&lt;digit&gt;
notation.
The string
\l
(\u)
causes the first character (actually inserted by the
substitution) that follows the
\l
(\u)
to be converted to lower-case (upper-case).
The strings
\L
(\U)
causes all characters subsequent
to them to be converted to lower-case (upper-case) as they are inserted
by the substitution until the string
\e
or
\E,
or the end of the
replacement string, is encountered.
<p>
An example of case conversion with the
<b>s</b>
command is as follows:
<pre>
<code>
<b>:</b>p
<b>The cat sat on the mat.</b>
<b>:</b>s/\&lt;.at\&gt;/\u&amp;/gp
<b>The Cat Sat on the Mat.</b>
<b>:</b>s/S\(.*\)M/S\U\1\eM/p
<b>The Cat SAT ON THE Mat.</b>
</code>
</pre>
<p>
In visual mode, a &lt;control&gt;-V &lt;control&gt;-M (or &lt;control&gt;-Q &lt;control&gt;-M)
sequence in the replacement string will be mapped to a
newline character, and so can be used to split lines.
A literal &lt;control&gt;-M requires escaping by preceding it with a backslash
(\^V^M
or
\^Q^M).
<h5><a name = "tag_001_014_598_052">&nbsp;</a>Edit Options in ex</h5>
<xref type="5" name="exedops"></xref>
The
<i>ex</i>
utility has a number of options that modify its behaviour.
These options have default settings, which can be changed using the
<b>set</b>
command.
<p>
Options are Boolean unless otherwise specified.
<h5><a name = "tag_001_014_598_053">&nbsp;</a>autoindent, ai</h5>
[Default <i>off</i>]
<p>
If
<b>autoindent</b>
is set, each line in input mode will be indented
(using first as many tab characters as possible,
as determined by the editor option
<b>tabstop</b>,
and then using space characters) to align with the previous line.
(Starting indentation will be determined by the line appended after, or the
line inserted before or the first line changed, with an
<b>a</b>,
<b>i</b>
or
<b>c</b>
command, respectively.)
When a newline character is inserted in the middle of a line,
and when
<b>autoindent</b>
is on, the first non-blank character to
the right of the cursor will be aligned to the current margin
on a new line immediately following the current line.
Any blank characters