/usr/share/mc/examples/macros.d/macro.7.sh is in mc-data 3:4.8.19-1.
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 | #silent
w delete trailing whitespace
TMPFILE=`mktemp ${MC_TMPDIR:-/tmp}/up.XXXXXX` || exit 1
cat %b > $TMPFILE
cat $TMPFILE | sed 's/[ \t]*$//' > %b
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