/usr/share/dynamic_reconfigure/msg/Config.msg is in libdynamic-reconfigure-config-init-mutex-dev 1.5.49-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 | BoolParameter[] bools
IntParameter[] ints
StrParameter[] strs
DoubleParameter[] doubles
GroupState[] groups
|