ch04_03.htm

unix基础教程

<tr><td><p><tt class="literal">LC_NUMERIC=</tt><em class="replaceable"><tt>locale</tt></em></p>
</td><td><p>(K93) Locale to use for the decimal-point character.
<a name="IXT-4-122739" /></p>
</td></tr>
<tr><td><p><tt class="literal">LINES=</tt><em class="replaceable"><tt>n</tt></em></p>
</td><td><p>(K) Screen's height; used for <tt class="literal">select</tt> lists.
<a name="IXT-4-122740" /></p>
</td></tr>
<tr><td><p><tt class="literal">MAIL=</tt><em class="replaceable"><tt>file</tt></em></p>
</td><td><p>Default file in which to receive mail; set by <tt class="literal">login</tt>.
<a name="IXT-4-122741" /></p>
</td></tr>
<tr><td><p><tt class="literal">MAILCHECK=</tt><em class="replaceable"><tt>n</tt></em></p>
</td><td><p>Number of seconds between mail checks; default is 600 (10 minutes).
<a name="IXT-4-122742" /></p>
</td></tr>
<tr><td><p><tt class="literal">MAILPATH=</tt><em class="replaceable"><tt>files</tt></em></p>
</td><td><p>
<a name="IXT-4-122743" />One or more files, delimited by a colon, in which to receive mail.
Along with each file, you may supply an optional message that the shell
prints when the file increases in size. Messages are separated
from the file name by a separator character.
The Korn shell separator is <tt class="literal">?</tt>, and the default message
is <tt class="literal">You have mail in $_</tt>.
<tt class="literal">$_</tt> is replaced with the name of the file.
The Bourne shell separator is <tt class="literal">%</tt>, and
the default message is <tt class="literal">You have mail</tt>.
For example, for <tt class="literal">ksh</tt>, you might have:


<blockquote><pre class="code">MAILPATH="$MAIL?Ring! Candygram!:/etc/motd?New Login Message"</pre></blockquote>

</p>
</td></tr>
<tr><td><p><tt class="literal">PATH=</tt><em class="replaceable"><tt>dirlist</tt></em></p>
</td><td><p>One or more pathnames, delimited by colons, in which to search
<a name="IXT-4-122744" />
for commands to execute.
Default for SVR4 is <tt class="literal">/bin:/usr/bin</tt>.
On Solaris, the default is
<tt class="literal">/usr/bin:</tt>.
However, the standard start-up scripts change it to:

<blockquote><pre class="code">/usr/bin:/usr/ucb:/etc:.</pre></blockquote>

<tt class="literal">ksh93</tt>: PATH is also searched for
function definitions
for undefined functions.</p>
</td></tr>
<tr><td><p><tt class="literal">PS1=</tt><em class="replaceable"><tt>string</tt></em></p>
</td><td><p>Primary prompt string; default is <tt class="literal">$</tt>.
<a name="IXT-4-122745" /></p>
</td></tr>
<tr><td><p><tt class="literal">PS2=</tt><em class="replaceable"><tt>string</tt></em></p>
</td><td><p>Secondary prompt (used in multiline commands); 
default is <tt class="literal">&gt;</tt>.</p>
</td></tr>
<tr><td><p><tt class="literal">PS3=</tt><em class="replaceable"><tt>string</tt></em></p>
</td><td><p>(K) Prompt string in <tt class="literal">select</tt> loops; default is <tt class="literal">#?</tt>.</p>
</td></tr>
<tr><td><p><tt class="literal">PS4=</tt><em class="replaceable"><tt>string</tt></em></p>
</td><td><p>(K) Prompt string for execution trace (<tt class="literal">ksh -x</tt> or <tt class="literal">set -x</tt>);
default is <tt class="literal">+</tt>.</p>
</td></tr>
<tr><td><p><tt class="literal">SHACCT=</tt><em class="replaceable"><tt>file</tt></em></p>
</td><td><p>&#8220;Shell account&#8221;; file in which to log executed shell scripts.
<a name="IXT-4-122746" />
Not in Korn shell.</p>
</td></tr>
<tr><td><p><tt class="literal">SHELL=</tt><em class="replaceable"><tt>file</tt></em></p>
</td><td><p>Name of default shell (e.g., <tt class="literal">/bin/sh</tt>).
<a name="IXT-4-122747" /></p>
</td></tr>
<tr><td><p><tt class="literal">TERM=</tt><em class="replaceable"><tt>string</tt></em></p>
</td><td><p>Terminal type.
<a name="IXT-4-122748" /></p>
</td></tr>
<tr><td><p><tt class="literal">TMOUT=</tt><em class="replaceable"><tt>n</tt></em></p>
</td><td><p>
<a name="IXT-4-122749" />(K) If no command is typed after <em class="emphasis">n</em> seconds, exit the shell.</p>
</td></tr>
<tr><td><p><tt class="literal">VISUAL=</tt><em class="replaceable"><tt>path</tt></em></p>
</td><td><p>
<a name="IXT-4-122750" />(K) Same as EDITOR, but VISUAL is checked first.</p>
</td></tr>
</table><p>

<a name="IXT-4-122751" /></div>

<a name="unut-ch-4-sect-3.4" /><div class="sect2"><h3 class="sect2">4.3.4. Arrays</h3><p>
<a name="IXT-4-122752" />
<a name="IXT-4-122753" />The Korn shell supports one-dimensional arrays of up to 1024 elements.
The first element is numbered 0.
An array <em class="emphasis">name</em> can be initialized as follows:</p>

<blockquote><pre class="code">set -A <em class="replaceable"><tt>name value0 value1 ...</tt></em></pre></blockquote>
<p>where the specified values become elements of <em class="emphasis">name</em>.
Declaring arrays is not required, however.  Any valid reference to
a subscripted variable can create an array.</p>
<p>
<a name="IXT-4-122754" />When referencing arrays, use the
<tt class="literal">${</tt> ... <tt class="literal">}</tt> syntax.
This isn't needed when referencing arrays
inside <tt class="literal">(( ))</tt> 
(the form of <tt class="literal">let</tt> that does automatic quoting).
Note that <tt class="literal">[</tt> and <tt class="literal">]</tt> are typed literally
(i.e., they don't 
stand for optional syntax).</p>

<table border="1" cellpadding="3">

<tr><td><p><tt class="literal">${</tt><em class="replaceable"><tt>name</em><tt class="literal">[</tt><em class="replaceable">i</tt></em><tt class="literal">]}</tt></p>
</td><td><p>Use element <em class="emphasis">i</em> of array <em class="emphasis">name</em>.
<em class="emphasis">i</em> can be any arithmetic expression
as described under <tt class="literal">let</tt>.
The expression must return a value between 0 and 1023.</p>
</td></tr>
<tr><td><p><tt class="literal">${</tt><em class="replaceable"><tt>name</tt></em><tt class="literal">}</tt></p>
</td><td><p>Use element 0 of array <em class="emphasis">name</em>.</p>
</td></tr>




<tr><td><p><tt class="literal">${</tt><em class="replaceable"><tt>name</tt></em><tt class="literal">[*]}</tt></p>
<p><tt class="literal">${</tt><em class="replaceable"><tt>name</tt></em><tt class="literal">[@]}</tt></p>
</td>

<td><p>Use all elements of array <em class="emphasis">name</em>.</p>
</td></tr>





<tr>
<td><p><tt class="literal">${#</tt><em class="replaceable"><tt>name</tt></em><tt class="literal">[*]}</tt></p>
<p><tt class="literal">${#</tt><em class="replaceable"><tt>name</tt></em><tt class="literal">[@]}</tt></p>
</td>

<td><p>Use the number of elements in array <em class="emphasis">name</em>.</p>
</td></tr>




</table><p>
<p><tt class="literal">ksh93</tt> provides associative arrays, where the indices
are strings instead of numbers (as in <tt class="literal">awk</tt>).
In this case,
<tt class="literal">[</tt> and <tt class="literal">]</tt> act like double quotes.
Associative arrays are created with <tt class="literal">typeset -A</tt>.
A special syntax


 
allows assigning to multiple elements at once:</p>

<blockquote><pre class="code">data=([joe]=30 [mary]=25)</pre></blockquote>
<p>The values would be retrieved as <tt class="literal">${data[joe]}</tt>
and <tt class="literal">${data[mary]}</tt>.</p>

<a name="IXT-4-122755" />
<a name="IXT-4-122756" />
<a name="IXT-4-122757" /></div>

<a name="unut-ch-4-sect-3.5" /><div class="sect2"><h3 class="sect2">4.3.5. Discipline Functions (ksh93 only)</h3><p>
<a name="IXT-4-122758" />
<a name="IXT-4-122759" />Along with structured variables,
<tt class="literal">ksh93</tt> introduces <em class="emphasis">discipline functions</em>.
These are special functions that are called whenever a variable's
value is accessed or changed.
For a shell variable named <tt class="literal">x</tt>, you can
define the following functions:</p>

<table border="1" cellpadding="3">

<tr><td><tt class="literal">x.get</tt></td><td><p>Called when <tt class="literal">x</tt>'s value
is retrieved (<tt class="literal">$x</tt>).</p>
</td></tr>
<tr><td><tt class="literal">x.set</tt></td><td><p>Called when <tt class="literal">x</tt>'s value
is changed (<tt class="literal">x=2</tt>).</p>
</td></tr>
<tr><td><tt class="literal">x.unset</tt></td><td><p>Called when <tt class="literal">x</tt> is
unset (<tt class="literal">unset x</tt>).</p>
</td></tr>
</table><p>
<p>Within the discipline functions, special variables provide information
about the variable being changed:</p>

<table border="1" cellpadding="3">

<tr><td><tt class="literal">.sh.name</tt></td><td><p>The name of the variable being changed.</p>
</td></tr>
<tr><td><tt class="literal">.sh.subscript</tt></td><td><p>The subscript of the array element being changed.</p>
</td></tr>
<tr><td><tt class="literal">.sh.value</tt></td><td><p>The value of the variable being assigned or
returned.  Changing it within the discipline function
changes the value that is actually assigned or returned.</p>
</td></tr>
</table><p>
</div>


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