Why doesn't delete mean delete?

[Victor Charlie]

Originally Posted by TriPolar

I agree in principle. But there are far worse cases of confusing name adaptation. And now we have the problem that every word and TLA* has been redefined for computers and they're being used over to mean different things. This is a minor one, and changing it is not practical.

Delete works in the way most people want it to most of the time. Consider the various cases:

First you have Delete as it works now, simply 'relocating' it in the recycle bin. You can still get it back.

Then you have the mode where the space used is reallocated for re-use, but it's still on the drive until the space is needed.

Then you have the mode where you want the data over-written so the original data can't be read without special equipment. And that takes more time.

Then you have the mode where you over-write the data repeatedly so that even special equipment can't detect what you've done.

All of those modes have variations as well, and there has to be a means of using each of them without accidently picking the wrong one. And computer users just don't like that idea. They want fewer options not more. I'm an old timer in this field and prefer text commands to point and click, and wouldn't mind entering commands like "nuke -fs -uig fname"** or "trash/expire=3/reuse=1"*** to get rid of a file. But most people just point and click, and want to use as little computerese as possible, which is why common words get re-used, and conf-used.

*TLA >>> Three letter acronym/abbreviation

**-fs -uig >>> -fromspace - untilitglows

***/expire=3/reuse=1 >>> keep for 3 days, reuse if space needed

obviously the last two are for fictitious OSs, but similar commands have been used.

Well, the problem, obviously, comes from the fact that the majority of regular people don't know all the distinctions, nor should they be expected to. Maybe this means that early programmers should've come up with a command that didn't leave the impression that a file was gone forever. To most people, I believe, delete is akin to shredding, or at least tearing up and throwing away, and data recovery amounts to piecing together those shredded pieces to reform the document. What they're not thinking is that delete actually means to hide the document in a different drawer and maybe throw some white-out on it when you get around to it. It's why so many average users are surprised if their deleted personal information is resurrected by crooks or the authorities. Many have come to learn that delete doesn't really mean destroy only because they've seen stories about good people being damaged or bad people getting caught for making the same logical assumptions. I only last year got my parents to understand they have to delete their deleteds.

Why couldn't they just give us the "Nuke it from space until it glows" button? Now that leaves no room for confusion.

[Lukeinva]

It used to, until Microsoft invented the Recycle Bin to help the poor souls who have itchy trigger fingers.

[njtt]

Originally Posted by gazpacho

Every new technology or science trys to explain itself in terms or what came before. You are basically demanding a detailed description for every action that is on the menu. What do you want the command or menu to say.
Delete

make_the_space_on_the_drive_available_but_don't_actually_remove_the_data_but_wait_it_sort_of_depends _on_the_actual_phsyical_mechanism_that_the_data_is_stored_on_please_refer_to_pages_1023_to_1054_of_m anual_number_7_for_a_more_detailed_explaination_of_everything_this_command_does

You are confused. That is what the OP might seem to be demanding. I, like you, am saying that it is silly.

Originally Posted by Victor Charlie

No, I would consider myself to have crossed it out. If you had deleted the text in your example it wouldn't be there.

Then you have failed to grasp the standard, accepted meaning of the word "delete":

American Heritage Dictionary of the English Language
de·lete
TRANSITIVE VERB:
de·let·ed, de·let·ing, de·letes
To remove by striking out or canceling: deleted some unnecessary words in the first draft.

Collins English Dictionary
delete
Definitions
verb tr
to remove (something printed or written); erase; cancel; strike out

Macmillan Dictionary
delete
to remove or cross out something that has been written

Cambridge Advanced Learner's Dictionary
delete
to remove or draw a line through something, especially a written word or words

There's glory for you!

It is really quite rare for "delete" to be used as a synonym for "destroy".

[Senegoid]

Originally Posted by gazpacho

Every new technology or science trys to explain itself in terms or what came before. You are basically demanding a detailed description for every action that is on the menu. What do you want the command or menu to say.
Delete

Well, the trend in programming languges and command-line interfaces does seem to move steadily in that direction.

make_the_space_on_the_drive_available_but_don't_actually_remove_the_data_but_wait_it_sort_of_depends _on_the_actual_phsyical_mechanism_that_the_data_is_stored_on_please_refer_to_pages_1023_to_1054_of_m anual_number_7_for_a_more_detailed_explaination_of_everything_this_command_does

This could well be the name of a Java function or a some command line parameter in Windows Server. I prefer camelCase myself.

Okay, back on-topic: I'd like at least a "casual secure default option", plenty sufficient for things like deleting that kiddie porn than you accidentally stumbled upon, from your browser cache. One to three random overwrites should be fine, but it has to be configurable to happen automatically on all deletes, not just when I explicitly ask for it, so it will get all those temp files and behind-the-scenes files like browser cache. When I tell my browser to delete cache, cookies, and everything, that's what I would like to have happen.

In modern multi-tasking systems, it doesn't have to be instant. It's fine if the freed blocks can simply be put into a queue to be deleted during idle time by a background process.

For modern complex disk systems, as Francis Vaughan discussed in detail above, there should be a "secure delete" option at the controller level, so that the system-level software can get more direct access to disk sectors, bypassing all the shuffling and optimizing that the controller does. Do you (Mr. Vaughan) mean to say that modern controllers don't have such a function?

[TriPolar]

Originally Posted by Victor Charlie

Why couldn't they just give us the "Nuke it from space until it glows" button? Now that leaves no room for confusion.

There's just not enough buttons to handle everybody's individual preferences. And programmable preferences seem to to just confuse the casual users.

I spent a little time with a UofP professor in the 70s who was working on a post graduate program for those who needed computer literacy. Primary computer literacy in those days meant programming in BASIC and learning that computers are full of a 1s and 0s. His students were past grads then getting their first introduction to the brave new world of computers. He found that it was easier to teach them APL (a cryptic symbolic language that required a special terminal for the characters) than BASIC, which was intended to be based on natural language. The common terms in BASIC like INPUT and PRINT were confusing them because of their preconceived notion of what those words meant. I think he really just transferred the confusion from one place to another though. Very few people ever learned to use APL, and I found most of them to be somewhat confused about something.

[Telemark]

Originally Posted by Senegoid

For modern complex disk systems, as Francis Vaughan discussed in detail above, there should be a "secure delete" option at the controller level, so that the system-level software can get more direct access to disk sectors, bypassing all the shuffling and optimizing that the controller does. Do you (Mr. Vaughan) mean to say that modern controllers don't have such a function?

But can't you configure disk arrays in (for example) various RAID configurations that require the knowledge of the controllers to know where the data lives? If you're using RAID 10 won't you'll have multiple disks to access multiple times to delete a single file. I don't see how you can bypass all that in any meaningful way. All storage devices would have to implement these new features, and all would have to implement them in similar ways.

[TriPolar]

Originally Posted by Telemark

All storage devices would have to implement these new features, and all would have to implement them in similar ways.

One of the points of an OS is to make the hardware logically independent. So at different levels, like say a driver, there needs to be similarity of implementation, but from there down things can change greatly. But on disk devices, generally, if you can write to the file, you'd do that before the logical delete and returning the sectors to the free list. For solid state drives it doesn't always work that way. New data written may not be stored in the same place as the older data. Some disks systems do this also, so the hardware manufacturer has to provide the functionality to guarantee nuking data from space until it glows.

[TriPolar]

Oh yeah, wait til you guys start using the cloud! It only gets worse from here on out!

[Victor Charlie]

Originally Posted by njtt

Quote:
American Heritage Dictionary of the English Language
de·lete
TRANSITIVE VERB:
de·let·ed, de·let·ing, de·letes
To remove by striking out or canceling: deleted some unnecessary words in the first draft.

Collins English Dictionary
delete
Definitions
verb tr
to remove (something printed or written); erase; cancel; strike out

Macmillan Dictionary
delete
to remove or cross out something that has been written

Cambridge Advanced Learner's Dictionary
delete
to remove or draw a line through something, especially a written word or words

There's glory for you!

It is really quite rare for "delete" to be used as a synonym for "destroy".

Then you have failed to grasp the standard, accepted meaning of the word "delete":

There's glory for you!

It is really quite rare for "delete" to be used as a synonym for "destroy".

You're kidding, right? Read your own definitions. "Erase", "remove"... others can be found that say expunge, etc. Those imply gone, disappeared, not crossed out for removal in future versions. See, you're using it in the sense of marking up text on a manuscript. I promise you that when deleting something, NOBODY expects the computer to draw a friggin' line through it.

Here's a simple test. Go to any program or website that allows you to type text. (Even this site will do.) Type a sentence. Any series of letters or numbers will do. Then highlight those words and letters. Then hit the delete button. What happens next? Does a line appear horizontally through the text or does it disappear?

[Victor Charlie]

Originally Posted by TriPolar

There's just not enough buttons to handle everybody's individual preferences. And programmable preferences seem to to just confuse the casual users.

I spent a little time with a UofP professor in the 70s who was working on a post graduate program for those who needed computer literacy. Primary computer literacy in those days meant programming in BASIC and learning that computers are full of a 1s and 0s. His students were past grads then getting their first introduction to the brave new world of computers. He found that it was easier to teach them APL (a cryptic symbolic language that required a special terminal for the characters) than BASIC, which was intended to be based on natural language. The common terms in BASIC like INPUT and PRINT were confusing them because of their preconceived notion of what those words meant. I think he really just transferred the confusion from one place to another though. Very few people ever learned to use APL, and I found most of them to be somewhat confused about something.

I'm pleased to have learned that the secure delete function on Macs pretty much accomplish that. But, I don't get the argument that there are so many preferences out there that it would confuse users. The confusion comes from all the reasons delete doesn't really mean a permanent delete (just look at this thread.) The personals preferences should come into play for those who don't want delete to actually mean delete.

[TriPolar]

Originally Posted by Victor Charlie

I'm pleased to have learned that the secure delete function on Macs pretty much accomplish that. But, I don't get the argument that there are so many preferences out there that it would confuse users. The confusion comes from all the reasons delete doesn't really mean a permanent delete (just look at this thread.) The personals preferences should come into play for those who don't want delete to actually mean delete.

Ok, but people freak out way more when they permanently delete something by accident than the other way around. I doubt that will change.

[friedo]

Originally Posted by Lukeinva

It used to, until Microsoft invented the Recycle Bin to help the poor souls who have itchy trigger fingers.

No it didn't. Filesystems have had the same delete semantics for half a century.

[njtt]

Originally Posted by Victor Charlie

You're kidding, right? Read your own definitions. "Erase", "remove"... others can be found that say expunge, etc. Those imply gone, disappeared, not crossed out for removal in future versions. See, you're using it in the sense of marking up text on a manuscript. I promise you that when deleting something, NOBODY expects the computer to draw a friggin' line through it.

Here's a simple test. Go to any program or website that allows you to type text. (Even this site will do.) Type a sentence. Any series of letters or numbers will do. Then highlight those words and letters. Then hit the delete button. What happens next? Does a line appear horizontally through the text or does it disappear?

You are totally incapable of reconsidering your position, right? Even when you are shown quite explicit evidence of your error, from multiple, highly authoritative sources.

All those definitions I gave include "draw a line through", or something that means that, such as "strike out". No-one, when writing, would delete by cutting a word out of the page and burning the scarp of paper containing it. Deleting something in the normal way, by drawing a line through it, marks it as to be ignored, but leaves it recoverable. (People sometimes erase writing with an eraser, which is a bit more destructive, and goes further toward making the original hard to recover, but they do not call that deleting. They call it erasing.) Obviously this is the original meaning, because writing long preceded the use of computers. The use of "delete" in reference to computing is a metaphor, and what computers actually do when you tell them to delete a file is, in fact, much more in accord with the true, original meaning of the word than what you would (apparently) like them to do. (What happens when you use the delete key on some unsaved text strains the metaphor a little more, although not in a way that matters. It is certainly not the paradigmatic, literal meaning of the word, which file deletion ought to imitate.) Computer system designers apparently have better English skills than you.

Also, as I already pointed out, in fact computers do sometimes interpret "delete" as, literally, "draw a line through". If I use the <del> (for delete) tag in HTML or BBcode, it does indeed draw a line through the word, thus. I would be very annoyed if use of such tags caused my text to disappear, and become unrecoverable.

You are wrong (about the English language) and computer system designers are right. What computers normally do when you tell them to delete a file is indeed appropriately called deleting, and what you would like them to do would better be called expunging, destroying, or (as it sometimes is called) erasing. It is useful to have different words for these functions, too, because, usually, what you really want to do is simply to delete a file rather than to expunge or erase it.

[Victor Charlie]

Originally Posted by TriPolar

Ok, but people freak out way more when they permanently delete something by accident than the other way around. I doubt that will change.

Unless you're one of the guys who gets greeted at the door by Chris Matthews.

[Victor Charlie]

Originally Posted by njtt

You are totally incapable of reconsidering your position, right? Even when you are shown quite explicit evidence of your error, from multiple, highly authoritative sources.

All those definitions I gave include "draw a line through", or something that means that, such as "strike out". No-one, when writing, would delete by cutting a word out of the page and burning the scarp of paper containing it. Deleting something in the normal way, by drawing a line through it, marks it as to be ignored, but leaves it recoverable. (People sometimes erase writing with an eraser, which is a bit more destructive, and goes further toward making the original hard to recover, but they do not call that deleting. They call it erasing.) Obviously this is the original meaning, because writing long preceded the use of computers. The use of "delete" in reference to computing is a metaphor, and what computers actually do when you tell them to delete a file is, in fact, much more in accord with the true, original meaning of the word than what you would (apparently) like them to do. (What happens when you use the delete key on some unsaved text strains the metaphor a little more, although not in a way that matters. It is certainly not the paradigmatic, literal meaning of the word, which file deletion ought to imitate.) Computer system designers apparently have better English skills than you.

,
Also, as I already pointed out, in fact computers do sometimes interpret "delete" as, literally, "draw a line through". If I use the <del> (for delete) tag in HTML or BBcode, it does indeed draw a line through the word, thus. I would be very annoyed if use of such tags caused my text to disappear, and become unrecoverable.

You are wrong (about the English language) and computer system designers are right. What computers normally do when you tell them to delete a file is indeed appropriately called deleting, and what you would like them to do would better be called expunging, destroying, or (as it sometimes is called) erasing. It is useful to have different words for these functions, too, because, usually, what you really want to do is simply to delete a file rather than to expunge or erase it.

This has obviously diverted into an absurd semantical game far removed from the point of the OP. But, what the hell. Such is the way of the SDMB.

The OP clearly relates to the elimination of files from a computer hard drive, not a strained, pedantic discussion on the subtleties of the definition of the word "delete." ("It depends on what the meaning of the word 'is' is.")

Also, as I already pointed out, in fact computers do sometimes interpret "delete" as, literally, "draw a line through". If I use the <del> (for delete) tag in HTML or BBcode, it does indeed draw a line through the word, thus.

Yeah, and sometimes a waiter will interpret "crabs" to be a tiny insect but that better not be when I'm ordering dinner.

You can conveniently ignore a substantive part of the definitions you yourself provided that define delete as removing, erasing, expunging, etc. We both know that the average user interprets delete in this way, not what it means to a manuscript editor, which is akin to "marked for removal in future drafts."

Again, what happens when you highlight text and hit the delete button? Don't pretend this isn't relevant with respect to how the average computer user interprets the word.

But, here's another thought experiment for you. Take 100 people with average computer skill. Hand them a document and tell them to delete it. What will most of them do? Wad it up and throw it in the trash? Tear it up? Shred it? Eat it? Or will they draw a big line through it, hide it in a drawer and tell you they'll come back some time in the future and write new words over it?

You can twist and torture the various definitions of the word, but to most people delete means permanently erase (even if they know some really smart guy may be able recover it.)

[Lukeinva]

Originally Posted by friedo

No it didn't. Filesystems have had the same delete semantics for half a century.

Not really. In the pre-Windows days (i.e. DOS) there was no easy method for recovering deleted files, for the general user. Sure, the data might still be on the disk but you would need some serious tools to get it back. When Windows introduced the Recycle Bin the difficulty of recovering a deleted file became a lot easier.

[friedo]

Originally Posted by Lukeinva

Not really. In the pre-Windows days (i.e. DOS) there was no easy method for recovering deleted files, for the general user. Sure, the data might still be on the disk but you would need some serious tools to get it back. When Windows introduced the Recycle Bin the difficulty of recovering a deleted file became a lot easier.

What's easy for the user is irrelevant to how the filesystem actually works. The idea of deleting an entry from a directory without overwriting the actual data is almost as old as dirt. And the "undelete" command in DOS was not hard to use.

[Topologist]

I know that much of the world now assumes that the computer world began with Windows, or possibly MS-DOS (for those who have long memories), but I do want to correct the misapprehension that Windows was the first operating system in which "delete" saved the file somewhere (the recycle bin) so that it could be easily recovered before being permanently removed from the file system (if not from the disk). I'll quickly mention that the Mac had its trash can from the start, before Windows, but the idea wasn't original there, either, of course. The earliest system I used that had a feature like this was a DEC TOPS-20 operating system (which came out in 1976). There, the DELETE command did not permanently remove a file, at least not right away. You could issue an UNDELETE command any time before you logged out to recover files you had deleted that session. I think this feature was in the earlier TENEX system as well, and likely came from earlier systems.

It would be interesting to know what was the oldest operating system to have a feature like this.

[beowulff]

Originally Posted by Topologist

I know that much of the world now assumes that the computer world began with Windows, or possibly MS-DOS (for those who have long memories), but I do want to correct the misapprehension that Windows was the first operating system in which "delete" saved the file somewhere (the recycle bin) so that it could be easily recovered before being permanently removed from the file system (if not from the disk). I'll quickly mention that the Mac had its trash can from the start, before Windows, but the idea wasn't original there, either, of course. The earliest system I used that had a feature like this was a DEC TOPS-20 operating system (which came out in 1976). There, the DELETE command did not permanently remove a file, at least not right away. You could issue an UNDELETE command any time before you logged out to recover files you had deleted that session. I think this feature was in the earlier TENEX system as well, and likely came from earlier systems.

It would be interesting to know what was the oldest operating system to have a feature like this.

As I recall, there was an expunge command in TOPS-20 if you really wanted the file to be irretrievable. Even then, I’m not sure if the OS wrote over the freed blocks.

[Topologist]

Originally Posted by beowulff

As I recall, there was an expunge command in TOPS-20 if you really wanted the file to be irretrievable. Even then, I’m not sure if the OS wrote over the freed blocks.

You're right, I meant to mention that. It's the equivalent of the modern "empty trash" and happened automatically when you logged out, IIRC. I very much doubt that TOPS-20 overwrote the freed blocks, but I don't know for sure. On the other hand, computers and storage were orders of magnitude slower then, so all the more reason not to spend time overwriting deleted files.

[pulykamell]

Originally Posted by Lukeinva

It used to, until Microsoft invented the Recycle Bin to help the poor souls who have itchy trigger fingers.

This is not true at all. My experience with computers only goes back to the 80s, and even back then Commodore 64s, when you deleted a file off disk, would only delete the directory entries to allow those sectors of the disk to be overwritten. Hence utilities like "undelete" that existed for the Commie 64. I'm not an expert on these things, but no computer I've ever owned actually wrote over the data when you deleted it by default. Hell, when you format a card in a camera or any other such device that uses flash memory, it doesn't clear out the bits (except some cameras would have a "low level format" option which would overwrite the whole card with either 0s or 1s [I forget which]). I've actually managed to save data from a corrupted CF card by formatting it. (Don't ask me how or why this worked, because I haven't the faintest clue. Using several file rescue utilities on the card itself only yielded something like 5 or 6 files of 200. I formatted the card, took seven pictures, ran the utilties again, and got all 200 plus files back.)

[ClaytonThroop]

Originally Posted by Victor Charlie

Again, what happens when you highlight text and hit the delete button? Don't pretend this isn't relevant with respect to how the average computer user interprets the word.

If you hit ctrl-z it comes back.

[BigT]

Deletion takes time. Why would you want to waste time deleting something rather than just write on top of it when the time comes? Most files aren't deleted because they are sooper sekert infoz--it's just because they are useless. If some information really does need to be destroyed, you can always do so.

The claim of some sort of financial conspiracy theories are hilarious, though. The ignorance about computers and their history, less so.

[Lukeinva]

Originally Posted by friedo

What's easy for the user is irrelevant to how the filesystem actually works. The idea of deleting an entry from a directory without overwriting the actual data is almost as old as dirt. And the "undelete" command in DOS was not hard to use.

Undelete is part of the PC-Tools command set; it's not an original PC- or MS-DOS command. And yes we all know that the operating system simply marks the sector of disk as available but that is knowledge that everyday users don't know.

[Victor Charlie]

Originally Posted by ClaytonThroop

If you hit ctrl-z it comes back.

Yes... and?

[gazpacho]

Originally Posted by Victor Charlie

Yes... and?

So delete does not mean gone forever in most computer contexts and hasn't for a very very long time.

[Francis Vaughan]

There is of course a difference between the trash/rubbish/recycle-bin/wastebasket and an undelete command. The bin makes explicit the two stage process. And Microsoft most certainly did not invent the idea. Not only was it on the Mac years before Microsoft had it, it was part of the desktop created by Xerox in the 70's and commercially available as Viewpoint on the Star workstation introduced in 1981. It was introduced to the market 4 months before IBM introduced the first ever PC with MS-DOS. The genesis of the Star was in the Xerox Alto, which was built in 1973 for internal research work. Microsoft was a very long way behind the curve.

[Lukeinva]

Originally Posted by gazpacho

So delete does not mean gone forever in most computer contexts and hasn't for a very very long time.

Some computer contexts. On the big mainframes (MVS) when a dataset is deleted it is gone. And it is not retrievable; there is no undelete or ctrl-z end of story. The only way to recover it is to restore it, and the source is from a backup which is intentionally taken (usually nightly). This is the only way to restore a dataset practically.

In fact, with RAID 5 (or 6 I forget which) it is almost impossible to 'go to the disk' and recover the tracks in raw format because the tracks are written in segments across 5 (or 6) disks in the array which only DFP keeps track of, or the internals of the machine. In the days of real 3390s retrieving data from one of the disks was probably something that could be accomplished but I never saw it.

In practice when you issue a delete command your data is gone. Unless you have some such undelete or unerase utility, and a lot of luck that nothing else was written to the disk before attempting a recover. Disassembling a hard drive to recover data is ridiculously hard and incredibly impractical that it isn't a solution for nearly every computer user.

This is what made the Windows recycle bin a very nice invention.

[bengangmo]

I just recovered 3.xx Gig of data from an "empty" SD card.

I recovered 40ish files from my most recent photo taking expedition and 58 from the one before that.

It was a revelation.

As a serious hard-core pervert, it is very easy for me to imagine using the camera for "fun" pictures, downloading them to whatever secure location I felt comfortable then deleting them from the SD card.

Only to have my wife come along, run a recovery programme and cut my balls off.

This seems to me to be rather illogical.

For my holiday snaps, I don't care whether they are deleted or not - I just want the space free for reuse (given that it's limited) and also a "fresh" set of photos for easy downloading (so that I don't have to worry about sorting).

For this sort of situation I guess the easy thing is to format the drive - which is fine if it is an SD card. But for your computer? Would it really be so difficult to have a command that meant "I really really really don't want this any more" and "Look, I just don't want this file taking up space and confusing me with too many files to search through"?

[Lukeinva]

Originally Posted by bengangmo

I just recovered 3.xx Gig of data from an "empty" SD card.

I recovered 40ish files from my most recent photo taking expedition and 58 from the one before that.

It was a revelation.

As a serious hard-core pervert, it is very easy for me to imagine using the camera for "fun" pictures, downloading them to whatever secure location I felt comfortable then deleting them from the SD card.

Only to have my wife come along, run a recovery programme and cut my balls off.

This seems to me to be rather illogical.

For my holiday snaps, I don't care whether they are deleted or not - I just want the space free for reuse (given that it's limited) and also a "fresh" set of photos for easy downloading (so that I don't have to worry about sorting).

For this sort of situation I guess the easy thing is to format the drive - which is fine if it is an SD card. But for your computer? Would it really be so difficult to have a command that meant "I really really really don't want this any more" and "Look, I just don't want this file taking up space and confusing me with too many files to search through"?

Such a command would get the absolute address of the file (beginning and end including extents) and write binary zeros on those tracks. Maybe such a tool exists I don't know.

PS-as for that SD drive a simple bash with a hammer would render it safe from the wife

[Victor Charlie]

Originally Posted by gazpacho

So delete does not mean gone forever in most computer contexts and hasn't for a very very long time.

Cntl-Z is an intentional action, like removing something from the trash bin before the collector takes it away. If you don't cntl-z, once you close the program those deleted items don't hang around until something else eventually overwrites them, they are gone forever.

[gazpacho]

Originally Posted by Lukeinva

Some computer contexts. On the big mainframes (MVS) when a dataset is deleted it is gone. And it is not retrievable; there is no undelete or ctrl-z end of story. The only way to recover it is to restore it, and the source is from a backup which is intentionally taken (usually nightly). This is the only way to restore a dataset practically.

In fact, with RAID 5 (or 6 I forget which) it is almost impossible to 'go to the disk' and recover the tracks in raw format because the tracks are written in segments across 5 (or 6) disks in the array which only DFP keeps track of, or the internals of the machine. In the days of real 3390s retrieving data from one of the disks was probably something that could be accomplished but I never saw it.

In practice when you issue a delete command your data is gone. Unless you have some such undelete or unerase utility, and a lot of luck that nothing else was written to the disk before attempting a recover. Disassembling a hard drive to recover data is ridiculously hard and incredibly impractical that it isn't a solution for nearly every computer user.

This is what made the Windows recycle bin a very nice invention.

If we want to bring things out of the home computer era it starts to get really hard to reliably erase a file. Where I work the unix computers have a huge set of backups. There are hourly backups that are captured 1, 2 and 3 hours ago, three sets of daily backups and three sets on monthly backups. People invest a lot of time and money into not deleting files.

[jtur88]

Is this something like the difference between "junk" and "trash" in my e-mail program?

And if I go back to edit this post, what is the difference between "delete" and "cancel"?

[fumster]

Originally Posted by Victor Charlie

Again, what happens when you highlight text and hit the delete button? Don't pretend this isn't relevant with respect to how the average computer user interprets the word.

It removes the word from view unless you hit "un-do". Similar to the recycle bin, no?

[fumster]

It seem like people are conflating three things:

1) Removing a file from the file system. For efficiency, this is done just writing as little as possible to disk. Depending on the implementation, you might have to write to just a few disk blocks to have all the blocks in the file placed on an unused block queue. Individual data blocks are still readable. Whole files might be retrievable , but it is non-trivial and depends on luck and knowledge of the underlying file system.

2) Modern "delete" which takes the file and moves it to the recycle directory . Recovery is trivial.

3) Writing over the contents of disk blocks so that there is no way of recovering data.

[RaftPeople]

Originally Posted by Victor Charlie

The OP clearly relates to the elimination of files from a computer hard drive,...

And it is exactly where the OP makes a mistake.

From the OS perspective, the term "delete" refers to the LOGICAL view of the system, not the physical view. A deleted object is no longer available to be referenced or acted upon (typically) by the functions provided, but it says nothing about how the system stores data.

Thinking that you can infer from a logical action what the underlying physical implementation looks like is a mistake, certainly a natural one for non-computer scientists, but still a mistake.

[Dog80]

Originally Posted by Lukeinva

Undelete is part of the PC-Tools command set; it's not an original PC- or MS-DOS command. And yes we all know that the operating system simply marks the sector of disk as available but that is knowledge that everyday users don't know.

I am quite sure undelete was included from MS-DOS 5.0 and onwards

[Measure for Measure]

MS-DOS 5.0 was released in May 1990 and was the first DOS version to include undelete. Microsoft licensed the technology from Central Point Software PC Tools. MS DOS 1.0 was released with the IBM PC in 1982.

The window for MS-DOS 5.0 was short: Windows 3.1 was released in March 1992 and the buggier Windows 3.0 was introduced in 1990. Those versions of Windows were built on top of DOS admittedly.

[TonySinclair]

I have the opposite problem as the OP. I cannot understand why there are still programs, like Winrar, that do not give you the option to use the Recycle Bin when they delete files. I mean, it's right there. You don't have to make it the default, but at least give us the option.

[fumster]

Originally Posted by Victor Charlie

Well, the problem, obviously, comes from the fact that the majority of regular people don't know all the distinctions, nor should they be expected to. Maybe this means that early programmers should've come up with a command that didn't leave the impression that a file was gone forever.

Maybe they should have called it remove and abbreviated it to "rm".

[Victor Charlie]

Originally Posted by fumster

Maybe they should have called it remove and abbreviated it to "rm".

That's a fine suggestion.

[Victor Charlie]

Originally Posted by fumster

It removes the word from view unless you hit "un-do". Similar to the recycle bin, no?

Yes, but once you close a program the cached words are gone for good, there's no undoing. Plus, there's a limit on the number of "undos" stored in cache. Files will hold in the bin indefinitely until you delete them from there.

[Victor Charlie]

Originally Posted by RaftPeople

And it is exactly where the OP makes a mistake.

From the OS perspective, the term "delete" refers to the LOGICAL view of the system, not the physical view. A deleted object is no longer available to be referenced or acted upon (typically) by the functions provided, but it says nothing about how the system stores data.

Thinking that you can infer from a logical action what the underlying physical implementation looks like is a mistake, certainly a natural one for non-computer scientists, but still a mistake.

Yes, from the OS perspective. From most users' perspective, delete doesn't mean it's been made unavailable. It means it's gone. That's the viewpoint taken by the OP.

[fumster]

Originally Posted by Victor Charlie

Yes, but once you close a program the cached words are gone for good, there's no undoing. Plus, there's a limit on the number of "undos" stored in cache. Files will hold in the bin indefinitely until you delete them from there.

In windows and many other programs the paste buffer is available after the program closes.

You should also take a look sometime at the metadata that word processing programs store in a file. There may be a list of all the revisions made to the file, who created the file, etc. There is also metadata stored in pictures taken with your digital camera. This may include the date, time, and geo-coordinates of where it was taken.

And BTW, Microsoft Paint doesn't use real paint.

[Unintentionally Blank]

It's both better and worse than y'all have stated thusfar in the thread.

Example the first:
1. Your iPhone's flash storage is encrypted by default. Good encryption as a rule, is indistinguishable from random noise. Lose the decryption key and the data is lost. Due to the design of the phone, EVEN IF you restored a PERFECT image of that data, PLUS KEY to another iPhone, it would be unrecoverable as aspects of the encryption rely on aspects of that particular phone.

2. There is, curiously enough, No such thing as a DoD wipe. (See Data Sanitization, here: http://en.wikipedia.org/wiki/DOD_5220.22-M ) As of the June 2007 edition of the DSS C&SM, overwriting is no longer acceptable for sanitization of magnetic media; only degaussing or physical destruction is acceptable.

3. last week I was able to boot a RAID 5 server with deleted files and successfully restore them...at the OS level the files were still recoverable.

4. At the same time, the 'clean room' recovery techniques really aren't feasable any more. Areal density is just too high if there isn't any residual disk structure information to go on. A single wipe of zeros will effectively make it forensically useless.

[clairobscur]

Originally Posted by BigT

Deletion takes time. Why would you want to waste time deleting something rather than just write on top of it when the time comes?.

At first I thought the same but then I'm remembering my recent attempt to recover an accidentally deleted file, with the computer throwing at me 35 000 recovered files. If I actually overwrote deleted files once in a while, I maybe would have had, say, 1000 or 2000 files to go through and might actually have found the file I was searching for.

Or maybe I could find a tool better at sorting out recovered files...

[DrCube]

Originally Posted by Victor Charlie

That's a fine suggestion.

https://en.wikipedia.org/wiki/Unix
https://en.wikipedia.org/wiki/Rm_%28Unix%29
https://en.wikipedia.org/wiki/Srm_%28Unix%29

[Steve MB]

Originally Posted by Lemur866

Bottom line is that normal deletion of your information would be enough to stop 99% of all attempts to recover that data, simply because nobody cares about your data. But if someone is willing to spend hundreds of thousands of dollars to recover your data, then physical destruction of your media is the only possible standard.

Not exactly, if by "normal deletion" you mean "select the file and hit the delete key". Data deleted that way can usually be recovered easily with fairly simple software tools if that part of the disk hasn't happened to get overwritten by something else. The bottom line is that if you keep anything on your computer that could cost you money or embarrassment if somebody dug it up, it's worth doing a secure delete. That said, a simple write-over-everything-once secure delete (as opposed to one of the high-level multi-stage overwrite protocols) will protect the data from anyone who isn't willing to spend thousands of dollars or the equivalent in in-house resources.

[yoyodyne]

Originally Posted by Steve MB

Not exactly, if by "normal deletion" you mean "select the file and hit the delete key". Data deleted that way can usually be recovered easily with fairly simple software tools if that part of the disk hasn't happened to get overwritten by something else. The bottom line is that if you keep anything on your computer that could cost you money or embarrassment if somebody dug it up, it's worth doing a secure delete. That said, a simple write-over-everything-once secure delete (as opposed to one of the high-level multi-stage overwrite protocols) will protect the data from anyone who isn't willing to spend thousands of dollars or the equivalent in in-house resources.

If you have a solid-state drive, overwrite isn't effective. The data has to have been encrypted with a key that is no longer available, or the entire drive wiped with the ATA secure erase command.

[sid manny]

Hi,

There is one software that can be used to delete the files permanently from the storage device. A couple of days ago I was able to shred files from SD card by using this software. With this software it is possible permanently delete the files from hard drive, memory card, external hard drive and pen drive. You can also download the demo tool from the internet and test the software.