more.html

unix 下的C开发手册,还用详细的例程。

characters needed to fill the columns.
The logical lines are written independently
of each other; that is,
commands affecting a single line affect them separately.
<p>
When standard output is a terminal and
<b>-u</b>
is not specified,
<i>more</i>
treats
backspace characters
and carriage-return characters
specially:
<ul>
<p>
<li>
A character, followed first by a
backspace character,
then by an underscore
(_),
will cause that character to be written
as underlined text, if the terminal type supports that.
An underscore, followed first by a
backspace character,
then any character, will also cause that character to be written
as underlined text, if the terminal type supports that.
<p>
<li>
A
backspace character
that appears between two
identical printable characters will cause
the first of those two characters to be written
as emboldened text (that is,
visually brighter, standout mode or inverse-video mode),
if the terminal type supports that, and the
second to be discarded.
Immediately subsequent occurrences of
backspaces/character pairs for that
same character will also be discarded.
(For example, the sequence
a\ba\ba\ba
is interpreted as a single emboldened
a.)
<p>
<li>
Other
backspace character
sequences will be written directly to the terminal,
which generally cause the character preceding the
backspace character
to be suppressed in the display.
<p>
<li>
A carriage-return character
at the end of a line will be ignored,
rather than being written as a control character,
as described in the next paragraph.
<p>
</ul>
<p>
It is implementation-dependent how other non-printable characters are written.
Implementations should use the same format that they use for the
<i><a href="ex.html">ex</a></i>
<b>print</b>
command.
<p>
If the
<b>-t</b>
option was specified,
<i>more</i>
will write a screen of the file containing the specified tag
in the current position.
<p>
If the
<b>-p</b>
option was specified,
<i>more</i>
will execute the command supplied in the
<i>command</i>
option-argument, and write the screen so that the
current position is the current position that
would result from applying that command to the input file.
<p>
If neither the
<b>-p</b>
or
<b>-t</b>
options were specified,
<i>more</i>
will write the first screen of the first input file.
<p>
Once the initial screen has been written,
<i>more</i>
will prompt the user and,
based on the interactive user input, will modify the screen or exit.
If the modification of the screen results in a screen that has lines in
common with the current screen,
<i>more</i>
will scroll the screen rather than
clearing and redrawing the screen
(unless the
<b>-c</b>
option is specified).
If the modification of the screen
results in a screen that has no lines
in common with the current screen,
<i>more</i>
will clear and redraw the screen.
<p>
If the standard output is not a terminal device,
<i>more</i>
will always exit when
it reaches end-of-file on the last file in its argument list.
Otherwise, for all
files but the last,
<i>more</i>
will prompt, with an indication
that it has reached the end-of-file, along with the name of
the next file.
For the last file specified, or for the
standard input if no file is specified,
<i>more</i>
will prompt,
indicating end-of-file, and accept additional commands.
If the next command specifies forward scrolling,
<i>more</i>
will exit.
If the
<b>-e</b>
option is specified,
<i>more</i>
will exit
immediately after writing the last line of the last file.
<p>
Several of the commands described in this section move the current position
backwards in the input stream.
In the case that text is being taken from a
non-rewindable stream, such as a pipe, it is implementation-dependent how much
backward motion is supported.
<p>
If a scrolling command cannot be performed
because there are insufficient lines
to scroll,
<i>more</i>
will alert the terminal.
The scrolling commands are
b,
&lt;control&gt;-B,
d,
&lt;control&gt;-D,
f,
&lt;control&gt;-F,
g,
G,
j,
k,
s,
u
and
&lt;control&gt;-U.
<p>
The interactive commands in the following sections are supported.
Some commands can
be preceded by a decimal integer, called
<i>count</i>
in the following descriptions.
If not specified with the command,
<i>count</i>
defaults to 1.
<p>
In the following descriptions,
<i>pattern</i>
is a basic regular expression, as described in
the <b>XBD</b> specification, <a href="../xbd/re.html#tag_007_003"><b>Basic Regular Expressions</b>&nbsp;</a> .
The term &quot;examine&quot; is historical usage meaning &quot;open
the file for viewing&quot;; for example,
<i>more</i>
<b>foo</b>
would be expressed as examining file
<b>foo</b>.
<h5><a name = "tag_001_014_1472_001">&nbsp;</a>Help</h5>
<pre>
<code>
<i>Synopsis</i>:   h
</code>
</pre>
<p>
Write a summary of these commands
and other implementation-dependent commands.
<h5><a name = "tag_001_014_1472_002">&nbsp;</a>Move Forward One Screenful</h5>
<pre>
<code>
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>f
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>&lt;control&gt;-F
</code>
</pre>
<p>
Move forward
<i>count</i>
lines, with a default of one screenful.
At end-of-file,
<i>more</i>
will continue with the next file in the list, or exit if the current
file is the last file in the list.
<h5><a name = "tag_001_014_1472_003">&nbsp;</a>Move Backward One Screenful</h5>
<pre>
<code>
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>b
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>&lt;control&gt;-B
</code>
</pre>
<p>
Move backward
<i>count</i>
lines, with a default of one screenful (see option
<b>-n</b>).
If
<i>count</i>
is more than the screen size, only the final screenful will be written.
<h5><a name = "tag_001_014_1472_004">&nbsp;</a>Scroll Forward One Line</h5>
<pre>
<code>
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>&lt;space&gt;
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>j
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>&lt;newline&gt;
</code>
</pre>
<p>
Scroll forward
<i>count</i>
lines.
The default
<i>count</i>
for the
space character
will be one screenful; for
j
and
newline character,
one line.
The entire
<i>count</i>
lines will be written, even if
<i>count</i>
is more than the screen size.
At end-of-file, a
newline character
will cause
<i>more</i>
to continue with the next file in the list, or exit if the current file
is the last file in the list.
<h5><a name = "tag_001_014_1472_005">&nbsp;</a>Scroll Backward One Line</h5>
<pre>
<code>
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>k
</code>
</pre>
<p>
Scroll backward
<i>count</i>
lines, with a default of 1.
The entire
<i>count</i>
lines will be written, even if
<i>count</i>
is more than the screen size.
<h5><a name = "tag_001_014_1472_006">&nbsp;</a>Scroll Forward One Half Screenful</h5>
<pre>
<code>
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>d
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>&lt;control&gt;-D
</code>
</pre>
<p>
Scroll forward
<i>count</i>
lines, with a default of one half of the screen size.
If
<i>count</i>
is specified, it will become the new default for
subsequent
<b>d</b>
and
<b>u</b>
commands.
<h5><a name = "tag_001_014_1472_007">&nbsp;</a>Skip Forward One Line</h5>
<pre>
<code>
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>s
</code>
</pre>
<p>
Skip forward
<i>count</i>
lines, with a default of 1, and write the next screenful
beginning at that point.
If
<i>count</i>
would cause the current position to be such
that less than one screenful would be written, the last
screenful in the file will be written.
<h5><a name = "tag_001_014_1472_008">&nbsp;</a>Scroll Backward One Half Screenful</h5>
<pre>
<code>
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>u
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>&lt;control&gt;-U
</code>
</pre>
<p>
Scroll backward
<i>count</i>
lines, with a default of one half of the screen size.
If
<i>count</i>
is specified, it will become the new default for
subsequent
<b>d</b>
and
<b>u</b>
commands.
<h5><a name = "tag_001_014_1472_009">&nbsp;</a>Go to Beginning of File</h5>
<pre>
<code>
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>g
</code>
</pre>
<p>
Go to line
<i>count</i>
in the file, with a default of 1 (beginning of file).
Scroll or rewrite the screen so that that line is at the current position.
<h5><a name = "tag_001_014_1472_010">&nbsp;</a>Go to End-of-file</h5>
<pre>
<code>
<i>Synopsis</i>:   <b>[</b><i>count</i><b>]</b>G
</code>
</pre>
<p>
Go to line
<i>count</i>
in the file, with a default of the end of the file.
If no
<i>count</i>
is specified, scroll or rewrite the screen so that the last line
in the file is at the bottom of the screen.
If
<i>count</i>
is specified,
scroll or rewrite the screen so that that line is at the current position.
<h5><a name = "tag_001_014_1472_011">&nbsp;</a>Refresh the Screen</h5>
<pre>
<code>
<i>Synopsis</i>:   r
<i>Synopsis</i>:   &lt;control&gt;-L
</code>
</pre>
<p>
Refresh the screen.
<h5><a name = "tag_001_014_1472_012">&nbsp;</a>Discard and Refresh</h5>
<pre>
<code>
<i>Synopsis</i>:   R
</code>
</pre>
<p>
Refresh the screen, discarding any buffered input.
If the current
file is non-seekable, buffered input will not be discarded and the
<b>R</b>
command is equivalent to the
<b>r</b>
command.
<h5><a name = "tag_001_014_1472_013">&nbsp;</a>Mark Position</h5>
<pre>
<code>
<i>Synopsis</i>:   m<i>letter
</i></code>
</pre>
<p>
Mark the current position with the letter named by
<i>letter</i>,
where
<i>letter</i>
represents the name of one of the lower-case letters of the
portable character set.
When a new file is examined, all marks may be lost.
<h5><a name = "tag_001_014_1472_014">&nbsp;</a>Return to Mark</h5>
<pre>
<code>
<i>Synopsis</i>:   '<i>letter</i>
</code>