Detecting kernel version upgrade

["William D. Jones" <thor0505%comcast.net@localhost>]

Hello all,

I use a cron script to pull changes from CVS and rebuild the NetBSD 
distributions for a variety of architectures each night. As expected, builds 
do not always succeed because the source tree is not guaranteed to compile. 
Most of these errors will fix themselves eventually. However, occasionally, 
I will run into errors that require a full rebuild. In particular, any time 
there is a kernel version upgrade, the builds will fail until I manually run 
a script to rebuild distributions from the beginning. As an example, such an 
error may look as follows:

=======  8 extra files in DESTDIR  =========
Files in DESTDIR but missing from flist.
File is obsolete or flist is out of date ?
------------------------------------------
./usr/X11R7/lib/libxcb-randr.so.0
./usr/X11R7/lib/libxcb-randr.so.0.1
./usr/X11R7/lib/libxcb-sync.so.0
./usr/X11R7/lib/libxcb-sync.so.0.1
./usr/X11R7/lib/libxcb.so.1
./usr/X11R7/lib/libxcb.so.1.1
./usr/lib/libssh.so.22
./usr/lib/libssh.so.22.0
=========  end of 8 extra files  ===========

For space reasons, I do not capture the output from each invocation of 
build.sh each night :P. I also cannot always check the build logs from my 
cron scripts each night (sometimes once a week). I've been looking into 
trying to autodetect kernel version upgrades so I can full rebuild without 
needing to manually run the script. The best I've come up with is the 
following grep command:

./gen_i386build.sh -u 2> /dev/null | grep -q "Files in DESTDIR but missing 
from flist."; echo $?

Ignoring the contrived example above, this requires saving output to an 
intermediate file; I need both the output of build.sh and grep to detect 
whether to rebuild, fail, or continue, so a pipe in non-bash will not work 
in my cron scripts. While I can't guard against all errors, is it possible 
to programmatically (and reliably) detect when a kernel version upgrade 
occurred so I can tailor my cron scripts to do a full rebuild during those 
cases? Even better would be to detect a kernel version upgrade BEFORE 
beginning the builds :).

As always, thanks in advance for any help.

Sincerely,

--
William D. Jones
Rowan University | ECE | 2012
Member IEEE
Member Tau Beta Pi
thor0505%comcast.net@localhost
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