dobby, I just tried what you said. First I tried putting the $ signs in but it didn't work so I assumed you put those in for some unknown techie reason but anyway I eventually got it to display this:
I understand that in OS X, when you move one, the other will follow. But I'm thinking that in OS 9, you can move one folder, and the other will stay put.
So you're just guessing about stuff and telling people to do stupid things that could destroy valuable data?
And I guess you wouldn't of cared if your "advice" caused Luca to lose a few year's worth of work?
So you're just guessing about stuff and telling people to do stupid things that could destroy valuable data?
And I guess you wouldn't of cared if your "advice" caused Luca to lose a few year's worth of work?
Listen Spart - quit being a jerk. I'm just trying to be helpful. That's what these forums are for. Did I say that was the answer? No. I said it's my best guess. It's people like you who destroy the spirit of these forums
Here's your new job "Spart":
1. Patrol this forum.
2. Whenever someone has a problem, find people who are trying to helpful, but give incorrect advice.
3. Give all of them a rude post, kind of like the one you did for me.
francis, your suggestion was well-intentioned, but could have resulted in really bad effects, and wasn't *really* put forth as "Well I'm not really sure, but..." Instead, it was: "Just do what I do..." which could sound rather authoritative to a neophyte. Which is why we jumped in to provide an alternate approach.
I also observed recently that I had two user folders. I run 10.2 on a multiuser machine. When I'm done I boot into OS9 for others to work in. So the systems get witched around a lot. Also, I work off a firewire drive most of the time, so i don't actually use my home folder much directly other than for e-mail etc.
Well, the sad news is I never did anything about the double home folder and just yesterday the HD crashed big time. I've used TechtoolPro, Disk Warrier and Apples Dsik tools without success. the directory is completely screwed and I can't get anything off the drive.
I'm not sure if the double home folder was an initial symptom, but if anyone reads this take note of how Luca fixed his Mac and how mine crashed and burned.
You have to be more specific, Carson... I had two identical "Users" folders. The "luca" (Home) folder within was not duplicated.
So if you looked at the contents of /Macintosh HD/ you'd see Applications, System, Library, Games, Users, and Users. But if you looked at the contents of /Macintosh HD/Users/ you'd see Home and Public, and that's it.
Did you have duplicate Home folders or duplicate Users folders? You said Home once and Users the other time in your post.
From the ln man page: "A hard link to a file is indistinguishable from the original directory entry; any changes to a file are effective independent of the name used to reference the file. Hard links may not normally refer to directories and may not span file systems."
It's the 'normally' that gets me... I could swear there were maaaaagical ways to produce hard links to directories, but you're right, that's probably not the case here.
Also, you are right that deleting a hard link will not erase the file. Overwriting with a NULL will, however, wipe the contents for all table entries. (Don't ask... bad bug, bad memories, don't wanna talk about it.)
First off, isn't one of Unix's ground principles: "a file is a file is a file"? As in: a file is a file, a directory is a file, a device is a file, they are just different kinds of file? May have thrown OS X in a loop, that one.
Second, I believe I read that deleting one hard link will not delete the file per se, it will only do so if that hard link was the LAST hard link referencing the file (of course, the file is then, after deleting the last hard link, still not deleted. It's still sitting on your drive, there's just no one who knows it. Unless of course you were paranoid and deleted in Terminal using rm with the -p flag.
Second, I believe I read that deleting one hard link will not delete the file per se, it will only do so if that hard link was the LAST hard link referencing the file (of course, the file is then, after deleting the last hard link, still not deleted. It's still sitting on your drive, there's just no one who knows it. Unless of course you were paranoid and deleted in Terminal using rm with the -p flag.
Yes. To be more precise: hard links are a reference counting mechanism added to the normal one-to-one mapping used in most disk allocation table lookup schemes. Creating a file creates one reference to that data. Making a hard link just adds another reference to the same space on the disk. Deleting a hard link just removes a reference. When you remove the last reference to the allocation blocks, you 'delete' the file by losing any pointers to it. In 'normal' situations, there's just one reference made when the file is created, and one reference (the last one) removed when the file is 'deleted'.
You have to be more specific, Carson... I had two identical "Users" folders. The "luca" (Home) folder within was not duplicated.
So if you looked at the contents of /Macintosh HD/ you'd see Applications, System, Library, Games, Users, and Users. But if you looked at the contents of /Macintosh HD/Users/ you'd see Home and Public, and that's it.
Did you have duplicate Home folders or duplicate Users folders? You said Home once and Users the other time in your post.
My bad, sorry. I had duplicate "Home" folders. I don't know why. As I said, I really never go in my home folder since I work from an external drive. Consequently i don't know how i would have inadvertantly duplicated it. Maybe someone managed to duplicate it, or maybe it was the beginning of the meltdown of my volume directory.
It's the 'normally' that gets me... I could swear there were maaaaagical ways to produce hard links to directories, but you're right, that's probably not the case here.
Hard links to directories are not uncommon:
"."
".."
But that's about it. No other hard links are permitted on OS X as far as I know. There are some UNIX flavours where root can actually create such hard links, you can sometimes bypass ln and use link(2) directly, but it doesn't seem to be possible on OS X.
As for why this isn't permitted: If it is allowed to make hard links to directories, you can create cycles which are hard to detect and lead to all sorts of problems. Also, if you can have several references to a directory, which one would be the parent? What would .. point to? Even though there may be good solutions, they are not trivial. Since there are hardly any benefits from this, it was decided to simply not allow it.
Comments
Originally posted by Luca Rescigno
dobby, I just tried what you said. First I tried putting the $ signs in but it didn't work so I assumed you put those in for some unknown techie reason
Code:
drwxrwxr-t 6 root wheel 204 Aug 30 03:49 Users
The $ is the command line prompt.
Originally posted by francisG3
I understand that in OS X, when you move one, the other will follow. But I'm thinking that in OS 9, you can move one folder, and the other will stay put.
So you're just guessing about stuff and telling people to do stupid things that could destroy valuable data?
And I guess you wouldn't of cared if your "advice" caused Luca to lose a few year's worth of work?
Originally posted by Spart
So you're just guessing about stuff and telling people to do stupid things that could destroy valuable data?
And I guess you wouldn't of cared if your "advice" caused Luca to lose a few year's worth of work?
Listen Spart - quit being a jerk. I'm just trying to be helpful. That's what these forums are for. Did I say that was the answer? No. I said it's my best guess. It's people like you who destroy the spirit of these forums
Here's your new job "Spart":
1. Patrol this forum.
2. Whenever someone has a problem, find people who are trying to helpful, but give incorrect advice.
3. Give all of them a rude post, kind of like the one you did for me.
Wouldn't that be fun?
francis, your suggestion was well-intentioned, but could have resulted in really bad effects, and wasn't *really* put forth as "Well I'm not really sure, but..." Instead, it was: "Just do what I do..." which could sound rather authoritative to a neophyte. Which is why we jumped in to provide an alternate approach.
I also observed recently that I had two user folders. I run 10.2 on a multiuser machine. When I'm done I boot into OS9 for others to work in. So the systems get witched around a lot. Also, I work off a firewire drive most of the time, so i don't actually use my home folder much directly other than for e-mail etc.
Well, the sad news is I never did anything about the double home folder and just yesterday the HD crashed big time. I've used TechtoolPro, Disk Warrier and Apples Dsik tools without success. the directory is completely screwed and I can't get anything off the drive.
I'm not sure if the double home folder was an initial symptom, but if anyone reads this take note of how Luca fixed his Mac and how mine crashed and burned.
So if you looked at the contents of /Macintosh HD/ you'd see Applications, System, Library, Games, Users, and Users. But if you looked at the contents of /Macintosh HD/Users/ you'd see Home and Public, and that's it.
Did you have duplicate Home folders or duplicate Users folders? You said Home once and Users the other time in your post.
Originally posted by Kickaha
From the ln man page: "A hard link to a file is indistinguishable from the original directory entry; any changes to a file are effective independent of the name used to reference the file. Hard links may not normally refer to directories and may not span file systems."
It's the 'normally' that gets me... I could swear there were maaaaagical ways to produce hard links to directories, but you're right, that's probably not the case here.
Also, you are right that deleting a hard link will not erase the file. Overwriting with a NULL will, however, wipe the contents for all table entries. (Don't ask... bad bug, bad memories, don't wanna talk about it.)
First off, isn't one of Unix's ground principles: "a file is a file is a file"? As in: a file is a file, a directory is a file, a device is a file, they are just different kinds of file? May have thrown OS X in a loop, that one.
Second, I believe I read that deleting one hard link will not delete the file per se, it will only do so if that hard link was the LAST hard link referencing the file (of course, the file is then, after deleting the last hard link, still not deleted. It's still sitting on your drive, there's just no one who knows it. Unless of course you were paranoid and deleted in Terminal using rm with the -p flag.
Originally posted by der Kopf
Second, I believe I read that deleting one hard link will not delete the file per se, it will only do so if that hard link was the LAST hard link referencing the file (of course, the file is then, after deleting the last hard link, still not deleted. It's still sitting on your drive, there's just no one who knows it. Unless of course you were paranoid and deleted in Terminal using rm with the -p flag.
Yes. To be more precise: hard links are a reference counting mechanism added to the normal one-to-one mapping used in most disk allocation table lookup schemes. Creating a file creates one reference to that data. Making a hard link just adds another reference to the same space on the disk. Deleting a hard link just removes a reference. When you remove the last reference to the allocation blocks, you 'delete' the file by losing any pointers to it. In 'normal' situations, there's just one reference made when the file is created, and one reference (the last one) removed when the file is 'deleted'.
Originally posted by Luca Rescigno
You have to be more specific, Carson... I had two identical "Users" folders. The "luca" (Home) folder within was not duplicated.
So if you looked at the contents of /Macintosh HD/ you'd see Applications, System, Library, Games, Users, and Users. But if you looked at the contents of /Macintosh HD/Users/ you'd see Home and Public, and that's it.
Did you have duplicate Home folders or duplicate Users folders? You said Home once and Users the other time in your post.
My bad, sorry. I had duplicate "Home" folders. I don't know why. As I said, I really never go in my home folder since I work from an external drive. Consequently i don't know how i would have inadvertantly duplicated it. Maybe someone managed to duplicate it, or maybe it was the beginning of the meltdown of my volume directory.
Originally posted by Kickaha
It's the 'normally' that gets me... I could swear there were maaaaagical ways to produce hard links to directories, but you're right, that's probably not the case here.
Hard links to directories are not uncommon:
"."
".."
But that's about it. No other hard links are permitted on OS X as far as I know. There are some UNIX flavours where root can actually create such hard links, you can sometimes bypass ln and use link(2) directly, but it doesn't seem to be possible on OS X.
As for why this isn't permitted: If it is allowed to make hard links to directories, you can create cycles which are hard to detect and lead to all sorts of problems. Also, if you can have several references to a directory, which one would be the parent? What would .. point to? Even though there may be good solutions, they are not trivial. Since there are hardly any benefits from this, it was decided to simply not allow it.