It is very unlikely that the startup command itself gives a problem. Without the content of server.cfg it can be hard to guess the problem.
Maybe you can use a workaround like:
echo a | openarena-0.8.1/oa_ded.i386 +set dedicated 2 +set port 27960 +exec server.cfg
I start my server with a script like this:
cd /path/to/openarena-0.8.1
while [ 0 -lt 1 ]; do
./oa_ded.i386 +set dedicated 2 +exec server_clean.cfg
done
and it works.