A hard link is file system entry that associates a name with another file on a file system.

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Why hard links not allowed to directories in UNIX/Linux

I read in text books that UNIX/Linux doesn't allows hard links to directories but soft links do. Is it because, when we have cycles and if we create hardlinks, and after some time we delete the ...
32
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2answers
1k views

Why is '.' a hard link in Unix?

I've seen many explanations for why the link count for an empty directory in Unix based OSes is 2 instead of 1. They all say that it's because of the '.' directory, which every directory has pointing ...
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7answers
8k views

What is the difference between symbolic and hard links?

When would you use one over the other?
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5answers
4k views

Why do hard links exist?

I know what hard links are, but why would I use them? What is the utility of a hard link?
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5answers
2k views

How to tell which file is original if hard link is created

For example, I have a file myold_file. Then I use ln to create a hard link as mylink: ln myold_file mylink Then, even by using ls -a, I cannot tell which is the old one. Is there anyway to tell?
15
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2answers
4k views

What happens when you delete a hard link?

If you do rm myFile where myFile is a hard link, what happens?
14
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3answers
2k views

Is there a limit of hardlinks for one file?

Is there a limit of number of hardlinks for one file? Is it specified anywhere? What are safe limits for Linux? And what for other POSIX systems?
12
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1answer
632 views

How to find all the links to a directory

When I stat a directory I get a listing that tell me there are 5 links to the directory. stat dir My question is how do I get information (names and locations) to all these 5 links?
9
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4answers
548 views

filesystem for archiving

I have some complex read-only data in my file system. It contains thousands of snapshots of certain revisions of a svn repository, and the output of regression tests. Identical files between snapshots ...
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2answers
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Dereferencing hard links

In the manual page of tar command, an option for following hard links is listed. -h, --dereference follow symlinks; archive and dump the files they point to --hard-dereference follow ...
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5answers
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Can I determine the number of sub-directories in a directory using `ls -l`?

When displaying directories using ls -l, their number of links (the second field in the output) is at least two: one for the dir name and one for . $ mkdir foo $ ls -l total 2 drwxr-xr-x 2 user ...
7
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4answers
4k views

How to copy directories with preserving hardlinks?

How to move directories that have files in common from one to another partition ? Let's assume we have partition mounted on /mnt/X with directories sharing files with hardlinks. How to move such ...
7
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1answer
80 views

Is there a way to express: `--link` or fall back to ordinary copy in cp (from GNU coreutils)?

Is there a way to tell cp to --link (i.e. create hard links), but fall back in the case where I am attempting inter-device hardlinks? Inter-device links aren't possible and would cause cp to fail. ...
7
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2answers
108 views

Why is there a mix of symlinks and hardlinks in /bin?

I understand the technical difference between symlinks and hardlinks, this is a question about their use in practice, particularly I'm curious to know why both are used in seemingly similar ...
6
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4answers
968 views

What's the difference between a hard links and copied files?

RHEL 6 My understanding is that hard links include a copy of the original file and that I could delete a hard-linked file in one directory, and it would still exist in the other directory. If ...
6
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2answers
2k views

How to `du` only the space used up by files that are not hardlinked elsewhere?

Using rsync --link-dest for space-saving snapshots, how can I figure out how much space I actually saved? Or more general: How to figure out how much space a directory uses considering only files ...
5
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2answers
304 views

Why do hard links seem to take the same space as the originals?

Thanks to some good Q&A around here and this page, I now understand links. I see hard links refer the same inode by a different name, and copies are different "nodes, with different names. Plus ...
5
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1answer
288 views

How to replace a symbolic link with an equivalent hard link?

Having a (single, no batch filesystem processing needed) symlink, what a command line to use to turn it into a hard link to the same file?
5
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2answers
198 views

Can a file be retrieved by its inode?

Run command like the following: $ln a b $ls -i a b 523669 a 523669 b $rm -f a $ls -i b 523669 b I concluded from this test that command rm actually removes the filename (a in this test) only ...
5
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1answer
180 views

Finding all the hard-links of a file without traversing the file system

I have seen in this page that inodes have a link counter to know how many files (read: "directory entry") point to this inode. Is there a way to know which directories contain such entries without ...
4
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4answers
411 views

Symbolic link and hard link questions

Let's say /A/B/c.sh is symbolic linked to /X/Y/c.sh. If c.sh has the command "./SOMETHING", '.' means /A/B/ or /X/Y/? How about the hard link?
4
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2answers
255 views

Can we use symbolic link and hard link for directories?

I know we can do that for files. What about directories? It seems that cpanel uses that a lot.
4
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2answers
106 views

Linux: How does hard-linking to a directory work?

I'm aware that Linux does not allow hard-linking to a directory. I read somewhere, that this is to prevent unintentional loops (or graphs, instead of the more desirable tree structure) in the ...
4
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1answer
47 views

“hard-linking” parts of a big file in which only a small part has changed

I use rsync to make backups: rsync -a --link-dest=PATHTO/$PREVIOUSBACKUP $SOURCE $CURRENTBACKUP This way I save space due to using hard links. The problem appears when I need to backup a huge file ...
4
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3answers
173 views

Why does mcedit recommend removing hardlinks when saving a file?

Whenever I use mcedit to edit a file that is hard linked somewhere and I want to save the file, the editor asks me if I want to remove the hard links. Is that common behavior on Linux or is mcedit ...
3
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4answers
469 views

What are inodes good for?

I wonder if storing the information about files in inodes instead of directly in the directory is worth the additional overhead. It may be well that I'm overestimating the overhead or overlooking some ...
3
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3answers
273 views

How to diff two folders by inodes

I'm currently using a script to backup files on my computer. In a nutshell, it works like this: rsync --link-dest=$FOLDER/current $SOURCE $DESTINATION However, I think that my script may be ...
3
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1answer
42 views

Where are information stored information about hard/soft links

Where does the *nix system store information about number of hard links to a specific inode? I can't find any information about that. Everywhere what a hard link is but rarely a bit more advanced ...
3
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1answer
96 views

How can I delete a hardlink to a directory?

Before I get 100s of answers that tell me it is impossible to hardlink directories in linux: yes, I know that. The file in question appeared in lost+fount after I checked the filesystem with e2fsck ...
3
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1answer
87 views

setgid binary doesn't have permission, mount's right, I'm missing something, but what, please?

I'm sorry, I know this has to be something simple but I've checked the manpages, the mount, the permissions ... (edit: combined history into one sequence as requested. Starting to seem a not-simple ...
3
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1answer
80 views

Files have the same inode but they don't link to each other

I have a bash script in two places and I can't remember how I created them. they have the same inode but none of them seem to link to another. is there a hard link but should not Links count for that ...
2
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3answers
460 views

Breaking a hard-link in-place?

I am keeping my dotfiles under version control and the script deploying them creates hard links. I also use etckeeper to put my /etc under version control. Recently I have gotten warnings like this: ...
2
votes
3answers
252 views

hardlink/softlink multiple file to one file

I have many files in a folder. I want to concatenate all these files to a single file. For example cat * > final_file; But this will increase disk space and also will consume time. Is there is a way ...
2
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2answers
194 views

Is a -rw-rw-rw- file really inaccessible inside a drwxrwx— directory?

Say I have a directory with these permissions: drwxrwx--- Inside this directory, a file with these permissions: -rw-rw-rw- Is the file readable/writable by everyone or not ? If not, how secure ...
2
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3answers
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`cp -al` snapshot whose hard links get directed to a new file when edited

I am trying to take snapshots of a massive folder regularly. I have read here: http://www.mikerubel.org/computers/rsync_snapshots/#Incremental that cp -al takes a snapshot of a folder by simply ...
2
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1answer
540 views

Hardlinks in Dropbox not updated

I want to create a backup of a single .tex file. I created the hard link to the file (which is not in Dropbox directory, lets say it is A) inside Dropbox directory. I did this so because I do not want ...
2
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3answers
244 views

Forcibly create directory hard link(s)?

I understand the reasoning why nearly every unix version doesn't allow hard-linking of directories (in fact HFS+ on OS X is the only one I know, but even that isn't made easy to do yourself). However, ...
2
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0answers
293 views

Multiple Linux or Unix Distributions, Same Home Partition or Data?

To avoid conflicts I have always installed multiple Linux and Unix distributions each with it's own home partion or directory, and in the era of 3TB hard drives this is often very practical; I also do ...
2
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0answers
90 views

Hard links vs. Soft links: When would you want to use one over the other? [duplicate]

Possible Duplicate: What is the difference between symbolic and hard links? Today, my teacher talked about the differences between 'hard links' and 'soft links', but she never really ...
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3answers
71 views

Seemingly Inconsistent Behavior for “ln” & “ln -s”

As we all know, the ln command creates a link, with the default being a hard link and the -s option creating a symlink. The general syntax is ln [-s] OLD NEW, where OLD is the file you are linking to ...
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2answers
872 views

Keep tracking of symbolic links?

I use symbolic links quite often, but after moving the original file, I lose track of the symbolic link. I also use symbolic links for keeping track of some files in the same directory, but again, I ...
1
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1answer
316 views

How do I manually modify an inode?

I am using Ubuntu Linux and, just for fun, I want to create a hardlink to a directory (as seen here). Because I'm just doing this for fun, I'm not looking for any sort of pre-developed ...
1
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1answer
72 views

If I hardlink to a directory, will the contents be “preserved” as if I hard-linked to every file?

I've seen people on the internet talk about using hardlinks to force files to stay on disk as a backup, even if they're deleted in their original location. Would this work for a directory too? Why or ...
1
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2answers
90 views

FS permission scenario

How can I achieve this files & folders permissions scenario: Consider these folder: Folder A: 640 root apache /var/www/A/ Folder www: 640 root apache /var/www/ and this linux user: id user1: ...
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1answer
167 views

rsync hardlink attempt copies

I've tried setting up a script to hardlink my files to my box.com account (as it's a backup of my music library). As I want to run it automatically to sync my music across several devices, I wanted to ...
1
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1answer
887 views

Backing up hard links (rsync)?

My question begins with: Do I actually have hard links on my disk at all (except for "." and ".." of course)? I'm not sure how I would find that out? If no, the question is already answered. If yes, ...
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3answers
36 views

How to get folder size ignoring hard links?

I use rsnapshot for backups, which generates a series of folders containing files of the same name. Some of the files are hard linked, while others are separate. For instance, hourly.1/file1 and ...
1
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1answer
47 views

is there some kind of symbolic links that support moving or renaming the target file?

I liked this explanation of hard and soft/symbolic links: http://unix.stackexchange.com/a/22406/42226 Now the reason why I googled about soft and hard links is simply because I was organizing my ...
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1answer
168 views

How to get a list all the “aliases” of a file (including of type directory) efficiently?

How can one get the list of all the aliases of a file (including of type directory) efficiently, given that a file: may have multiple hard links, multipe soft links, multi-level soft links may be ...
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2answers
98 views

mlbackup / rsync / hard links data size

I am new to mlbackup/rsync and the concept of hard links, so I am a little confused after creating a backup data set via mlbackup. So here's the scenario: I am backing up "folder A" to "folder B". ...