First, it seems like you forgot the <tstamp />
tag in your target so that the ${DSTAMP}
and ${TSTAMP}
variables work.
Then you should define your properties like this :
<property name="build.dbdeploy.deployfile" value="deploy-${DSTAMP}${TSTAMP}.sql" />
<property name="build.dbdeploy.undofile" value="undo-${DSTAMP}${TSTAMP}.sql" />
They should be automatically placed in the directory you specified in the dir
argument.