/usr/share/doc/cadabra/reserved/equals.tex is in cadabra 1.29-1ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 | \cdbreserved{equals}{}
Denotes equalities. The parser rewrites an infix \verb|=| operator
using an \verb|\equals| object.
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