ROOTCMD in cfengine script

[Per Foreby]

On Sat, 18 Aug 2007, Thomas Lange wrote:

>>>>>> On Sat, 18 Aug 2007 18:52:20 +0200 (CEST), Per Foreby <perf at ddg.lth.se> said:
>
>    > 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.
>
>    >    shellcommands:
>    >      any::
>    >        ${ROOTCMD} /usr/sbin/update-texmf
>
>    > The error from cfengine says that the command must be an absolute path,
> IMO this error is because chroot is not used as /sbin/chroot but
> only as chroot in $ROOTCMD. You may define $ROOTCMD in a class/*.var file.

But i got the error message when doing a softupdate, and then $ROOTCMD 
is set to nothing, so it is not the missing path for chroot that is the 
problem.

I did some testing, and the problem seems to be ROOTCMD= (empty) in 
/usr/sbin/fai. I tried to come up with some commands that just executed 
its arguments without the need for quoting (like /bin/sh -c). Writing 
such a "shell" is of cource easy. I would know since I have written 
a number of them for restricted environments, but now I tried to find 
something out-of-the-box. This worked:

   ROOTCMD="/usr/bin/nice -n 0"

But then I found an even simpler soulution:

   ROOTCMD=" "

This works togeter with "noabspath=true"

This is what my test script looked like:

   control:
     actionsequence = ( shellcommands )

   shellcommands:
     any::
       "${ROOTCMD} /usr/bin/touch /root/tt" noabspath=true


Setting ROOTCMD to " " doesn't affect shell scripts, so I would suggest 
a change in /usr/sbin/fai:


     ROOTCMD="/usr/sbin/chroot $FAI_ROOT"
     # no chroot needed
     [ "$FAI_ROOT" = '/' ] && ROOTCMD=" "

Or, to be safe if chroot would move to another directory:

     ROOTCMD="`which chroot` $FAI_ROOT"
     # no chroot needed
     [ "$FAI_ROOT" = '/' ] && ROOTCMD=" "

For the time beeing I will put this in a *.var script.

/Per