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Does mv on a FAT filesystem actually rename or does it copy and delete?


On Sat, 3 Feb 2018 12:23:57 +0100, Ralf Mardorf wrote:
>>PPS: IOW I was mistaken, you seemingly ask, if the operation is
>>atomic. Yes, "mv" within the same partition/directory does "rename",
>>it does not copy and remove (delete).
>>
>>However, I might be mistaken, so use google, or much better run
>>strace.
>>
>>[rocketmouse at archlinux ~]$ cd /tmp/dir_3/
>>[rocketmouse at archlinux dir_3]$ ls -hAl
>>total 0
>>-rw-r--r-- 1 rocketmouse rocketmouse 0 Feb  3 11:46 test_new
>>[rocketmouse at archlinux dir_3]$ strace mv -i test_new test_new_2
>>[snip]
>>rename("test_new", "test_new_2")        = 0
>>[snip]
>>+++ exited with 0 +++
>>[rocketmouse at archlinux dir_3]$ ls -hAl
>>total 0
>>-rw-r--r-- 1 rocketmouse rocketmouse 0 Feb  3 11:46 test_new_2  
>
>My apologize for the confusion, sometimes it's not easy to understand
>a novice's request at the first time ;). As already pointed out above,
>it does change the directory entry, it does not copy and rename
                                                          ^^^^^^
                                                          a typo, this
                                                          should read
                                                          "remove" :D
>(delete). It plausibly shouldn't work that way, when coping a dir or
>file to another partition/mount point. Anyway, "strace" still is your
>friend to verify or falsify my claim.



-- 
https://www.schneier.com/blog/archives/2018/01/spectre_and_mel_1.html