doc/multidefine.html


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<h1> The <tt>multidefine</tt> program </h1>

<p>
<tt>multidefine</tt> splits a value and defines several variables at once,
then executes another program.
</p>

<h2> Interface </h2>

<p>
 In an <a href="execlineb.html">execlineb</a> script:
</p>

<pre>
     multidefine [ -0 ] [ -r ] [ -C | -c ] [ -n ] [ -d <em>delim</em> ] <em>value</em> { <em>variables...</em> } <em>prog...</em>
</pre>

<ul>
 <li> <tt>multidefine</tt> reads a <a href="el_semicolon.html">block</a>
containing a list of variables. That block must not be empty. </li>
 <li> <tt>multidefine</tt> <a href="el_transform.html">splits</a>
<em>value</em>, and performs other operations depending on the given
options. </li>
 <li> <tt>multidefine</tt> performs
<a href="el_substitute.html">parallel substitution</a> on
<em>prog...</em>, using all of the <em>variables</em> in the block as keys.
The first word in the split <em>value</em> is assigned to the first
<em>variable</em>, the second word is assigned to the second <em>variable</em>,
and so on. Every <em>variable</em> is substituted with exactly one word. </li>
 <li> If a <em>variable</em> is the empty word, then the word in the split
<em>value</em> corresponding to its position is not substituted. So you can
use empty words to pad the list of variables and only perform substition
on the relevant fields. </li>
 <li> <tt>multidefine</tt> then execs into the modified <em>prog...</em>. </li>
</ul>

<h2> Options </h2>

<ul>
 <li> <tt>-0</tt>&nbsp;: if there are more <em>variables</em> in the block than
there are words in the split <em>value</em>, the excess variables
will be replaced with zero word. Without this option, the excess variables are
replaced with the empty word. </li>
 <li> <tt>-r</tt>&nbsp;: behave similarly to the "read" shell command.
If there are more words in the split <em>value</em> than there are
<em>variables</em> in the block, the last variable will be replaced with all
the remaining words (and will be split). Without this option, the last variable
is replaced with a single word, and the excess words are lost. </li>
</ul>

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