4 ms·

My number-one wish for a NGS: Undo! Take, for example, rm. The hoops we have to jump through when accidentally rm'ing a file are ridiculous [1]. But in most c

by maho 10y ago

My number-one wish for a NGS: Undo! Take, for example, rm. The hoops we have to jump through when accidentally rm'ing a file are ridiculous [1]. But in most cases (smallish, non-secret files), rm should be trivially undoable. Windows gets this right: By default, files are not deleted, but moved to trash. If there is not enough space in trash, Windows warns you. Or, if you really want to delete a file instead of moving it to trash, you can press SHIFT+DELETE, in which case Windows will also warn you that it can't be undone. (What is missing in Windows is a "nuke" option that overwrites the old bits with random data, for those rare cases where a file must be purged from the system completely.) But in most cases, after deleting a file, you can simply press CTRL+Z to get it back. It is possible to make rm behave like that in Linux [2], but in a NGS, this should be the default behaviour (in my view), with "delete" for really deleting (unlinking) a file, and "nuke" for completely distroying a file, as seperate commands. Undo is hard. Most programs are on their third, fourth, or even higher release before getting it right. (Mathematica 10 is stil trying to get there...) But I think we should try harder to solve the undo-problem with respect to file-system interactions, or with respect to system-settings, in Linux. [1]: http://unix.stackexchange.com/questions/10883/where-do-files-go-when-the-rm-command-is-issued http://unix.stackexchange.com/questions/10883/where-do-files... [2]: http://unix.stackexchange.com/questions/42757/make-rm-move-to-trash http://unix.stackexchange.com/questions/42757/make-rm-move-t...

CaptSpify 10y ago
Although I kind of agree with you, I'll play the devil's-advocate: If you actually care about the file, it should have a backup that you can restore from anyway. And, depending on the file, that backup should be source-control.
- blakeyrat 10y ago
  If the solution to the problem relies on human beings being fully-informed, entirely competent, and never making mistakes-- it's not a very good solution, IMO. Yes, people should maintain backups. But if people don't, for whatever reason (maybe they've never heard the word "backup" before; maybe they typed the wrong command and thought they had backups all along, etc.) shouldn't be screwed if something goes wrong.
- gherkin0 10y ago
  I know you're playing devil's advocate, but that attitude is making the perfect the enemy of the good. Backups are non-trivial enough that many people don't set them up correctly if at all; and even if they do, a restore can take some work. I think it's perfectly reasonable to have relatively painless alternative (e.g. "undo_rm") as an extra layer of safety.
- ansible 10y ago
  Backups are good. More frequent backups are even better. I have btrfs snapshots run on the fileservers at 10 minute intervals. Which, of course, captures the entire filesystem state, not just files that you have deleted by accident.
koolba 10y ago
I bet you could solve this with ZFS and automatic snapshot creation for each new command. Want to undo the past N commands? Roll back to a previous snapshot!
- i336_ 10y ago
  And a policy mechanism that lets you define how important a directory (or file) is and how hard the system will work (eg removing less-important data to free up space) to save this. This idea falls over if the amount of data you create (which the shell can't know in advance) is too big to contain in a snapshot. All that would be possible is an automatic notification that the operations in XYZ directory are no longer undoable due to its size.
athenot 10y ago
On the flip side, you can have multiple filesystem entries (via hard links) to the same set of files and set up your own playground directory while keeping a mirror view of the same directory. Remove a file from dir A, and it's still in dir B. Once you're satisfied with the result, you can delete the entire dir B. Accidentally removed a file from A? Restore it from B by making another hard link. (Caveat: hard links don't work with directories unless you're Apple TimeMachine)
Natanael_L 10y ago
It would require the programs to explicitly describe their actions to the shell and by default behaving in a reversible manner. That would allow you to single out effects you dislike, and tell it to undo it. Kind of like making the shell behave in relation to your OS as an editor/IDE + version control system, rather than just as an editor/IDE. Old versions are preserved until you purge them. Or perhaps it would just simulate state changing actions by default, waiting to be told to execute them.
Arnavion 10y ago
>Windows gets this right: By default, files are not deleted, but moved to trash. The del or Remove-Item commands also permanently delete the file, just like rm. The "Windows" behavior you're talking about is the behavior of the graphical shell Explorer, which is also present in Gnome and KDE. There's nothing specific to Windows here.
- shawnz 10y ago
  That said, i'd like a "del to recycle bin" in Windows too.
  - JdeBP 10y ago
    Then get yourself off to https://jpsoft.com/ https://jpsoft.com/ , set the Delete To Recycle Bin option on in the configuration tool (https://jpsoft.com./help/inistartupdlg.htm https://jpsoft.com./help/inistartupdlg.htm), and enjoy exactly that. (-:
- Symbiote 10y ago
  apt install trash-cli alias rm=trash Done? This implements the Freedesktop specification, so is compatible with what KDE and Gnome do. https://github.com/andreafrancia/trash-cli https://github.com/andreafrancia/trash-cli
- maho 10y ago
  You are right, I forgot about Gnome and KDE. I tend to use classic shells on Linux, and the graphical shell on Windows, so I made a wrong generalization. It's probably more accurate to say that "undo" of simple operations (rm, mv) is something graphical shells get right. But why are classic shells shipped without even the simplest "undo" features? We can probably all tell stories-from-the-trenches of how we accidentally did something aweful by typing the wrong command. Sometimes, it's hosing the network configuration of a remote machine, which is not something where "undo" would help you. However, in my experience, most cases involve doing something foolish with rm or mv, where "undo" would be tremendously helpful. I guess the main reason why I don't use the text shells of Windows is that Windows explorer gives me Ctrl+Z, which is saving my behind approximately once per year. As a final thought, all shells (graphical or not) should expand the undo-features beyond rm and mv. For example, if I change system settings (or even Application settings?) and am not happy, I would love to be able to simply "undo" them, without trying to remember what the previous setting was. I realize that this is an incredibly hard problem, and that it is unlikely to be solved in an evolutionary step of the existing shells. That's why hearing about NGS got me so excited.
fao_ 10y ago
If I haven't misread, you're proposing a replacement to rm that has support for undo? Why not just make a shell script that uses mv to place the item in, say, ~/.deleted and drop it in your PATH?
ParrotyError 10y ago
Back in the 90s (IIRC) someone wrote a kernel module for linux that provided the equivalent of a GUI "trash can/recycling bin" but at the filesystem level, where a specific directory (folder for you young 'uns) was set aside for the deleted files. Because it was a kernel module (filesystem driver) it was transparent to applications, including the shell.
- botw 10y ago
  lost+found? it's still there in each file system but i never see a real usage for it.
  - Crespyl 10y ago
    I believe that's less an everyday-use "trashcan" and more of an ext* feature for recovering from filesystem corruption; "Something broke and I think I've recovered all the files, but I've forgotten where some of them were supposed to go".

by maho 10y ago

CaptSpify 10y ago

Although I kind of agree with you, I'll play the devil's-advocate: If you actually care about the file, it should have a backup that you can restore from anyway. And, depending on the file, that backup should be source-control.

blakeyrat 10y ago
If the solution to the problem relies on human beings being fully-informed, entirely competent, and never making mistakes-- it's not a very good solution, IMO. Yes, people should maintain backups. But if people don't, for whatever reason (maybe they've never heard the word "backup" before; maybe they typed the wrong command and thought they had backups all along, etc.) shouldn't be screwed if something goes wrong.
gherkin0 10y ago
I know you're playing devil's advocate, but that attitude is making the perfect the enemy of the good. Backups are non-trivial enough that many people don't set them up correctly if at all; and even if they do, a restore can take some work. I think it's perfectly reasonable to have relatively painless alternative (e.g. "undo_rm") as an extra layer of safety.
ansible 10y ago
Backups are good. More frequent backups are even better. I have btrfs snapshots run on the fileservers at 10 minute intervals. Which, of course, captures the entire filesystem state, not just files that you have deleted by accident.

koolba 10y ago

I bet you could solve this with ZFS and automatic snapshot creation for each new command. Want to undo the past N commands? Roll back to a previous snapshot!

i336_ 10y ago
And a policy mechanism that lets you define how important a directory (or file) is and how hard the system will work (eg removing less-important data to free up space) to save this. This idea falls over if the amount of data you create (which the shell can't know in advance) is too big to contain in a snapshot. All that would be possible is an automatic notification that the operations in XYZ directory are no longer undoable due to its size.

athenot 10y ago

On the flip side, you can have multiple filesystem entries (via hard links) to the same set of files and set up your own playground directory while keeping a mirror view of the same directory. Remove a file from dir A, and it's still in dir B. Once you're satisfied with the result, you can delete the entire dir B. Accidentally removed a file from A? Restore it from B by making another hard link. (Caveat: hard links don't work with directories unless you're Apple TimeMachine)

Natanael_L 10y ago

It would require the programs to explicitly describe their actions to the shell and by default behaving in a reversible manner. That would allow you to single out effects you dislike, and tell it to undo it. Kind of like making the shell behave in relation to your OS as an editor/IDE + version control system, rather than just as an editor/IDE. Old versions are preserved until you purge them. Or perhaps it would just simulate state changing actions by default, waiting to be told to execute them.

Arnavion 10y ago

>Windows gets this right: By default, files are not deleted, but moved to trash. The del or Remove-Item commands also permanently delete the file, just like rm. The "Windows" behavior you're talking about is the behavior of the graphical shell Explorer, which is also present in Gnome and KDE. There's nothing specific to Windows here.

shawnz 10y ago
That said, i'd like a "del to recycle bin" in Windows too.
- JdeBP 10y ago
  Then get yourself off to https://jpsoft.com/ https://jpsoft.com/ , set the Delete To Recycle Bin option on in the configuration tool (https://jpsoft.com./help/inistartupdlg.htm https://jpsoft.com./help/inistartupdlg.htm), and enjoy exactly that. (-:
Symbiote 10y ago
apt install trash-cli alias rm=trash Done? This implements the Freedesktop specification, so is compatible with what KDE and Gnome do. https://github.com/andreafrancia/trash-cli https://github.com/andreafrancia/trash-cli
maho 10y ago
You are right, I forgot about Gnome and KDE. I tend to use classic shells on Linux, and the graphical shell on Windows, so I made a wrong generalization. It's probably more accurate to say that "undo" of simple operations (rm, mv) is something graphical shells get right. But why are classic shells shipped without even the simplest "undo" features? We can probably all tell stories-from-the-trenches of how we accidentally did something aweful by typing the wrong command. Sometimes, it's hosing the network configuration of a remote machine, which is not something where "undo" would help you. However, in my experience, most cases involve doing something foolish with rm or mv, where "undo" would be tremendously helpful. I guess the main reason why I don't use the text shells of Windows is that Windows explorer gives me Ctrl+Z, which is saving my behind approximately once per year. As a final thought, all shells (graphical or not) should expand the undo-features beyond rm and mv. For example, if I change system settings (or even Application settings?) and am not happy, I would love to be able to simply "undo" them, without trying to remember what the previous setting was. I realize that this is an incredibly hard problem, and that it is unlikely to be solved in an evolutionary step of the existing shells. That's why hearing about NGS got me so excited.

fao_ 10y ago

If I haven't misread, you're proposing a replacement to rm that has support for undo? Why not just make a shell script that uses mv to place the item in, say, ~/.deleted and drop it in your PATH?

ParrotyError 10y ago

Back in the 90s (IIRC) someone wrote a kernel module for linux that provided the equivalent of a GUI "trash can/recycling bin" but at the filesystem level, where a specific directory (folder for you young 'uns) was set aside for the deleted files. Because it was a kernel module (filesystem driver) it was transparent to applications, including the shell.

botw 10y ago
lost+found? it's still there in each file system but i never see a real usage for it.
- Crespyl 10y ago
  I believe that's less an everyday-use "trashcan" and more of an ext* feature for recovering from filesystem corruption; "Something broke and I think I've recovered all the files, but I've forgotten where some of them were supposed to go".