/usr/share/avogadro/fragments/alkanes/ is in avogadro-data 1.2.0-1+deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/share/avogadro/fragments/alkanes/2-methylpropane.cml
/usr/share/avogadro/fragments/alkanes/butane.cml
/usr/share/avogadro/fragments/alkanes/decane.cml
/usr/share/avogadro/fragments/alkanes/dodecane.cml
/usr/share/avogadro/fragments/alkanes/eicosane.cml
/usr/share/avogadro/fragments/alkanes/ethane.cml
/usr/share/avogadro/fragments/alkanes/heptane.cml
/usr/share/avogadro/fragments/alkanes/hexadecane.cml
/usr/share/avogadro/fragments/alkanes/hexane.cml
/usr/share/avogadro/fragments/alkanes/methane.cml
/usr/share/avogadro/fragments/alkanes/nonane.cml
/usr/share/avogadro/fragments/alkanes/octane.cml
/usr/share/avogadro/fragments/alkanes/pentadecane.cml
/usr/share/avogadro/fragments/alkanes/pentane.cml
/usr/share/avogadro/fragments/alkanes/propane.cml
/usr/share/avogadro/fragments/alkanes/tetracosane.cml
/usr/share/avogadro/fragments/alkanes/tetradecane.cml
/usr/share/avogadro/fragments/alkanes/tridecane.cml
/usr/share/avogadro/fragments/alkanes/undecane.cml