fail=0
du --exclude=x a | sed 's/^[0-9][0-9]* //' | sort > out || fail=1
-printf '===\n'
+printf '===\n' >> out
printf 'b\n' > excl
-du --exclude-from=excl a | sed 's/^[0-9][0-9]* //' | sort > out || fail=1
+du --exclude-from=excl a | sed 's/^[0-9][0-9]* //' | sort >> out || fail=1
cat <<\EOF > exp
-a/b/c
+a
a/b
-a/u/v
+a/b/c
a/u
-a
-===
-a/x/y
-a/x
a/u/v
-a/u
+===
a
+a/u
+a/u/v
+a/x
+a/x/y
EOF
cmp out exp || fail=1
-test $fail = 1 && diff out exp 2> /dev/null
+test $fail = 1 && diff -u out exp 2> /dev/null
(exit $fail); exit $fail