bug#36831: Enhance directory move. (was Re: bug#36831: enhance 'directory not empty' message)
Hello, On 2019-08-02 9:56 p.m., L A Walsh wrote: On 2019/08/02 19:47, Assaf Gordon wrote: Can new merging features be added to 'mv'? yes. But it seems to me these would be better suited for 'higher level' programs (e.g. a GUI file manager). --- But neither the person who posted the original bug on this nor I are using a GUI, we are running 'mv' GUI, we use the cmd line on linux, so that wouldn't be of any use. The original post was about the error *message*, asking to make it clearer. That is the topic of this thread (and the previous patch) - so let's leave them at that. I see you started a new thread ( https://bugs.gnu.org/36901 ), so I'll reply there.
bug#36831: Enhance directory move. (was Re: bug#36831: enhance 'directory not empty' message)
On 2019/08/02 19:47, Assaf Gordon wrote: > Can new merging features be added to 'mv'? yes. > But it seems to me these would be better suited for 'higher level' > programs (e.g. a GUI file manager). --- But neither the person who posted the original bug on this nor I are using a GUI, we are running 'mv' GUI, we use the cmd line on linux, so that wouldn't be of any use. If the command was named 'ren', then I'd expect it to be dummer, but 'mv'/move seem like it should be able to move files from one dir into another. But you say posix wants it to perform as a rename? I know, create a 're' command (or 'rn') for rename, and have it do what 'mv' would do. Maybe posix would realize it would be better to have re/rn behave like rename, and 'mv' to behave it was moving something. So if I have: mkdir A B touch A/foo B/fee So when I look at the system call on linux for rename: oldpath can specify a directory. In this case, newpath must either not exist, or it must specify an empty directory. (complying with POSIX_C_SOURCE >= 200809L) So move should give an error: Nope: mv A B > tree B B ├── A │ └── foo └── fee 1 directory, 2 files So mv is violating POSIX - it didn't do the rename, but moved A under B and neither dir had to be empty. Saying it has to follow POSIX when it doesn't appear to, seems a bit contradictory?
bug#36831: Enhance directory move. (was Re: bug#36831: enhance 'directory not empty' message)
Hello, On Fri, Aug 02, 2019 at 02:41:31AM -0700, L A Walsh wrote: > On 2019/07/28 23:28, Assaf Gordon wrote: > > > > > > $ mkdir A B B/A > > $ touch A/bar B/A/foo > > $ mv A B > > mv: cannot move 'A' to 'B/A': Directory not empty > > > > And the reason (as you've found out) is that the target directory 'B/A' > > is not empty (has the 'foo' file in it). > > Had this been allowed, moving 'A' to 'B/A' would result in the 'foo' > > file disappearing. > > > --- > Why must foo disappear? > > Microsoft Windows handles this situation by telling the user that > the target directory already exists and giving the option to *MERGE* > the directories. > > If you attempt to move a file into a directory that already contains > a file by the same name, it pops up another notice asking [...] Certainly, GUI programs (and more 'feature-rich' programs than 'mv') offer many "merging" options. I'm sure Midnight-Commander, KDE/Doplhine, XFCE/Thunar, Gnome/Nautilus and many other free software GUI file managers have some "merging" capabilities. But 'mv' is more basic and does not have this capability. Partly that is because it adheres to the POSIX standards, which mandates: "3. The mv utility shall perform actions equivalent to the rename() function [...]" https://pubs.opengroup.org/onlinepubs/9699919799/utilities/mv.html Some rsync options (--remove-source-files) can mimick 'mv' with merging, but then they are more like "copy+delete" than actual "rename/move". Can new merging features be added to 'mv'? yes. But it seems to me these would be better suited for 'higher level' programs (e.g. a GUI file manager). regards, - assaf
bug#36831: Enhance directory move. (was Re: bug#36831: enhance 'directory not empty' message)
On 2019/07/28 23:28, Assaf Gordon wrote: > > > $ mkdir A B B/A > $ touch A/bar B/A/foo > $ mv A B > mv: cannot move 'A' to 'B/A': Directory not empty > > And the reason (as you've found out) is that the target directory 'B/A' > is not empty (has the 'foo' file in it). > Had this been allowed, moving 'A' to 'B/A' would result in the 'foo' > file disappearing. > --- Why must foo disappear? Microsoft Windows handles this situation by telling the user that the target directory already exists and giving the option to *MERGE* the directories. If you attempt to move a file into a directory that already contains a file by the same name, it pops up another notice asking if you want to replace the old with the new, keep it as it is (file won't be moved and in this case, old directory would still exist with the unmoved files left in it), or keep both with the new file getting a name variant (like foo.exe -> foo_1.exe, keeping the extension the same so as to not mess up the identity of the contents. But in all the cases, a file with a non-conflicting name wouldn't disappear from the target.
