/etc/default/a-rex is in nordugrid-arc-arex 5.0.5-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | # To enable a-rex, i.e. to indicate that a readily usable
# configuration is in place, comment out or delete the
# following line.
RUN=no
|