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<p>
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<h1> The <tt>$@</tt> program </h1>
<p>
<tt>$@</tt> prints the positional parameters of an execline script.
</p>
<h2> Interface </h2>
<pre>
$@ [ -n ] [ -0 | -d <em>delimchar</em> ]
</pre>
<ul>
<li> <tt>$@</tt> reads the number <em>n</em> of "positional
parameters" in the <tt>#</tt> environment variable. If that variable
is not set or does not contain a valid <em>n</em>, <tt>$@</tt>
exits 100. </li>
<li> <tt>$@</tt> prints the value of the <tt>1</tt> environment
variable, then <em>delimchar</em>, then the value of the <tt>2</tt>
environment variable... and so on until <tt><em>n</em></tt>. If one of
these variables is not set, <tt>$@</tt> exits 100. </li>
<li> If everything runs OK, <tt>$@</tt> exits 0. This makes it
one of the rare "exiting" execline commands. </li>
</ul>
<h2> Options </h2>
<ul>
<li> <tt>-n</tt> : <em>chomp</em>. Do not print the last
<em>delimchar</em>. </li>
<li> <tt>-d</tt> <em>delimchar</em> : use the character
<em>delimchar</em> as separator between the arguments. Default: <tt>\n</tt>.
If <em>delimchar</em> has more than one character, only the first one is
used. If <em>delimchar</em> is the empty string, then <tt>$@</tt>
will output the positional parameters as a
<a href="el_transform.html#netstrings">sequence of netstrings</a> (and the
<tt>-n</tt> option will be ignored). </li>
<li> <tt>-0</tt> : use the null character as separator. Any <tt>-d</tt>
argument will be ignored. Warning: this option should only be used to feed
data to programs that know how to handle null-separated lists. </li>
</ul>
<h2> Notes </h2>
<ul>
<li> The <tt>$@</tt> word gets interpreted by execline as the list of
all positional parameters. To make sure it's not substituted, and
correctly refers to the <tt>$@</tt> command, make sure to escape the
<tt>$</tt> character in execline scripts: <tt>\\$@</tt>. </li>
<li> You can use <tt>$@ -d ""</tt> along with the
<a href="forbacktickx.html">forbacktickx</a> command to reliably loop
over the positional parameters:
<pre>
#!/command/execlineb
forbacktickx -d "" ARG { \\$@ -d "" }
dosomething $ARG
</pre>
will call <tt>dosomething</tt> in turn on each argument to the script.
That will work even if those arguments contain spaces, newlines,
or other fancy characters. </li>
<li> Alternatively, instead of encoding data into a netstring, you can
use a null-separated list, which will work the same way:
<pre>
#!/command/execlineb
forbacktickx -0 ARG { \\$@ -0 }
dosomething $ARG
</pre> </li>
</ul>
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