/usr/share/bedtools/test/closest/mdb1.bed is in bedtools-test 2.25.0-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3
chr1 5 15 d1.1 1 + chr1 20 60 d1.2 2 - chr1 200 220 d1.3 3 -