<! banner_id > The <code>SYSTEM</code> macro takes one argument: a command to execute. The command is run via the standard C function <code>system</code>. The presence of this macro in the Yodl language introduces the danger of <em>live data</em>; imagine someone sending you a document with <pre> SYSTEM(rm *) </pre> <p>in it. To avoid such malevolent side effects, the <code>yodl</code> program has a flag <code>-l</code> to define the `live data policy'. By default, <code>-l0</code> is implied which suppresses the <code>SYSTEM</code> macro and the related <code>PIPETHROUGH</code> macro. See also section ??. <p>Despite the potential danger, <code>SYSTEM</code> can be useful in many ways. E.g., you might want to log when someone processes your document, as in: <p><pre> SYSTEM(echo Document processed! | mail myself@my.host) </pre> <p><!-- if this file ./Documentation/footer.html.in is present, it is included automatically by add-html-footer, and replaces the simple standard footer substitutions: * index, * package name * package name * ENV:WEBMASTER, * ENV:WEBMASTER --> <hr> Go <a href=>back</a> to index of Yodl. <p> Please send Yodl questions and comments to <a href="mailto:yodl@icce.rug.nl"> <em>yodl@icce.rug.nl</em></a>. <p> <!-- package Yodl Yodl --> Please send comments on these web pages to <a href="mailto:(address unknown)"><em>(address unknown)</em></a> <p> Copyright (c) 1997, 1998, 1999 Karel Kubat and Jan Nieuwenhuizen. <p> Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.<p> <hr><font size=-1> This page was built from Yodl-1.31.18 by <address><br> <<a href=\"mailto:(address unknown)\">(address unknown)</a>>, Wed Mar 5 04:36:20 2008 EST.</address><p></font></BODY> </html>