我刚刚创建的备份与
rsync -av --delete projects/ /Volumes/daten/projects/
后来我跑
diff -r projects/ /Volumes/daten/projects/
只是为了检查，如果一切正常并不期待任何来自diff的输出。然而，DIFF发现很多不同之处。这是否意味着rsync的不正确同步我的数据？
更新：重新运行时rsync的它似乎罚款，没什么rsync的做：
$ rsync -av --delete projects/ /Volumes/daten/projects/
building file list ... done
sent 470414 bytes received 20 bytes 188173.60 bytes/sec
total size is 295619054 speedup is 628.40
然而，DIFF也不会停止生成输出，好像有很多不同的文件。这里是一个小摘录：
$ diff -r projects/ /Volumes/daten/projects/
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_dep/debug/package_dependencies/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_dep/debug/package_dependencies/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:41 CST 2018
---
> #Sun Nov 04 19:34:13 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_1/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_1/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:41 CST 2018
---
> #Sun Nov 04 19:34:14 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_2/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_2/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:41 CST 2018
---
> #Sun Nov 04 19:34:14 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_3/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_3/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:42 CST 2018
---
> #Sun Nov 04 19:34:14 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_4/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_4/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:42 CST 2018
---
> #Sun Nov 04 19:52:00 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_5/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_5/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:42 CST 2018
---
> #Sun Nov 04 19:34:14 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_6/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_6/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:42 CST 2018
---
> #Sun Nov 04 19:34:14 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_7/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_7/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:42 CST 2018
---
> #Sun Nov 04 19:34:14 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_8/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_8/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:42 CST 2018
---
> #Sun Nov 04 19:34:14 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_9/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/ir_slices/debug/package_slice_9/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:42 CST 2018
---
> #Sun Nov 04 19:34:14 CET 2018
diff -r projects/CatClicker/app/build/intermediates/incremental/packageInstantRunResourcesDebug/tmp/debug/dex-renamer-state.txt /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental/packageInstantRunResourcesDebug/tmp/debug/dex-renamer-state.txt
1c1
< #Sat Dec 08 16:17:34 CST 2018
---
> #Sun Nov 04 19:33:52 CET 2018
Binary files projects/CatClicker/app/build/intermediates/incremental-classes/debug/instant-run-bootstrap.jar and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-classes/debug/instant-run-bootstrap.jar differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/compat/R$color.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/compat/R$color.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/coreui/R$color.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/coreui/R$color.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/coreutils/R$color.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/coreutils/R$color.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/fragment/R$color.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/fragment/R$color.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/graphics/drawable/R$color.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/graphics/drawable/R$color.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/graphics/drawable/animated/R$color.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/graphics/drawable/animated/R$color.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/mediacompat/R$color.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/mediacompat/R$color.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/v4/R$color.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/v4/R$color.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/v7/appcompat/R$anim.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/v7/appcompat/R$anim.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/v7/appcompat/R$color.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/android/support/v7/appcompat/R$color.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/cyberdynesoftware/catclicker/R$attr.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/cyberdynesoftware/catclicker/R$attr.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/cyberdynesoftware/catclicker/R$bool.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/cyberdynesoftware/catclicker/R$bool.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/cyberdynesoftware/catclicker/R$dimen.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/cyberdynesoftware/catclicker/R$dimen.class differ
Binary files projects/CatClicker/app/build/intermediates/incremental-verifier/debug/cyberdynesoftware/catclicker/R$drawable.class and /Volumes/daten/projects/CatClicker/app/build/intermediates/incremental-verifier/debug/cyberdynesoftware/catclicker/R$drawable.class differ
看来，很多文件都不会被看作是rsync的“不同”。默认情况下，rsync的只是检查文件大小和文件的最后修改时间戳。请尝试使用rsync与-c/--checksum选项打开校验，然后再次运行“差异”。
从rsync手册页摘录：
-c，--checksum
这改变了这样的rsync检查文件是否被更改，都需要转移的。如果没有这个选项，rsync使用“快速检查”如果（默认）检查每个文件的大小和发送者和接收者之间的最后一次修改比赛时间。这个选项来改变这个比较128位校验和具有匹配的大小每个文件。生成的校验意味着双方将花费大量的磁盘I / O读取文件的所有数据的传输（这是在此之前，将完成转移已更改的文件任意读取），所以这可以减缓东西下来显著。