\subsection{cron}
This module allows to install commands into SICS which will be repeated
 periodically. The syntax is: sicscron intervall command. intervall is
the time intervall and command is the command to execute.  A problem
is I/O becasue the original connection which installed the cron job
may be lost. Therefore cron commands are executed within the context
of special connection which does not do socket output. All I/O will be
logged into the command log though for  control. As
this is a single system facility all data structure will be defined
in the implementation file. The public interface to this is just the
installation routine. This stuff is implemented in the files
sicscron.h and sicscron.c. 

The installation routine installs another task into the SICS system
which will invoke the command to be executed at the predefined
intervalls.