[root@bass test]# mkdir A B
[root@bass test]# tree A
A
└── lin
0 directories, 1 file
[root@bass test]# tree B
B
└── lin
0 directories, 1 file
[root@bass test]# echo "hello A" > A/lin
[root@bass test]# echo "hello B" > B/lin
[root@bass test]# diff -rq A B
Files A/lin and B/lin differ
[root@bass test]# echo "hello A" > B/lin
[root@bass test]# diff -rq A B
[root@bass test]#
[root@bass test]# mkdir A/a
[root@bass test]# mkdir B/b
[root@bass test]# diff -rql A B
Only in A: a
Only in B: b
Files A/lin and B/lin differ
[root@bass test]# diff -rql A B
Only in A: a
Only in B: b
Files A/lin and B/lin differ
[root@bass test]# ls
A B
[root@bass test]# mv A/a/ A/x
[root@bass test]# tree A
A
├── lin
└── x
1 directory, 1 file
[root@bass test]# mv B/b B/x
[root@bass test]# tree B
B
├── lin
└── x
1 directory, 1 file
[root@bass test]# diff -rq A B
Files A/lin and B/lin differ
[root@bass test]# cat A/lin
hello A
[root@bass test]# cat B/lin
hello B
[root@bass test]# touch A/x/chen
[root@bass test]# touch B/x/chen
[root@bass test]# diff -rq A B
Files A/lin and B/lin differ
[root@bass test]# echo "hello chen" > A/x/chen
[root@bass test]# echo "hello chen" > B/x/lin
[root@bass test]# diff -rq A B
Files A/lin and B/lin differ
Files A/x/chen and B/x/chen differ
Only in B/x: lin
