The SYSTEM macro takes one argument: a command to execute. The command is run via the standard C function system. The presence of this macro in the Yodl language introduces the danger of live data; imagine someone sending you a document with
SYSTEM(rm *)

in it. To avoid such malevolent side effects, the yodl program has a flag -l to define the `live data policy'. By default, -l0 is implied which suppresses the SYSTEM macro and the related PIPETHROUGH macro. See also section ??.

Despite the potential danger, SYSTEM can be useful in many ways. E.g., you might want to log when someone processes your document, as in:

SYSTEM(echo Document processed! | mail myself@my.host)


Go back to index of Yodl.

Please send Yodl questions and comments to yodl@icce.rug.nl.

Please send comments on these web pages to (address unknown)

Copyright (c) 1997, 1998, 1999 Karel Kubat and Jan Nieuwenhuizen.

Verbatim copying and distribution of this entire article is permitted in any medium, provided this notice is preserved.


This page was built from Yodl-1.31.18 by

<(address unknown)>, Tue Apr 15 19:40:40 2008 MSD.