ROOTCMD in cfengine script

[Per Foreby]

Is it possible to use $ROOTCMD in cfengine scripts?

I update a configuration file for tex-common, and want to run 
update-texmf after that. It must work both for install and softupdate.

This is what I tried with in my script:

   shellcommands:
     any::
       ${ROOTCMD} /usr/sbin/update-texmf

The error from cfengine says that the command must be an absolute path, 
and since I tried this on a softudate where $ROOTCMD should be a null 
string, $ROOTCMD might not be exported to the script. Or would an empty 
string cause this problem?

I resorted to using a separate shell-script, but it would be nice to 
have everything in the same script.

I would probably be able to create a class script which defines 
FAI_ACTION as a class, and then check for that class in the cfengine 
script:

   shellcommands:
     install::
       /sbin/chroot /tmp/target /usr/sbin/update-texmf
     softupdate::
       /usr/sbin/update-texmf

Does anyone have a better idea?

/Per