Linux – “ln -L” (–logical) for

hardlinklinuxlnproc

I can read in the ln man page:

   -L, --logical
          make hard links to symbolic link references

I read somewhere that ln -L could be used to re-link files that were deleted but which are still open, using the /proc filesystem. For example:

ln -L /proc/1234/fd/12 /tmp/my-file

But I'm getting ENOENT: No such file or directory. If I try on a different filesystem, I get instead Invalid cross-device link.

If I can't use ln -L to recover deleted files, then what could it be used for?

Best Answer

GNU utilities are primarily documented with info pages. From the GNU ln info page:

‘-L’
‘--logical’
    If -s is not in effect, and the source file is a symbolic link,
    create the hard link to the file referred to by the symbolic link,
    rather than the symbolic link itself.

So this simply dereferences symbolic links given as source arguments.

Related Solutions

Linux – How to recover open but deleted file on Linux using ln instead of cp

Try using tail to copy the file continually:

tail -c +0 -f /proc/$pid/fd/$fd > filename

Of course, you will have to stop the tail process by hand (or some other external means) when the download has finished.

Linux – When would creating a hard link be useful

Hardlinks help us organize our file system in a much more flexible way. Basically, hardlinks allow us to take one file and have it be in multiple places in the filesystem at once. Think about a scenario where you are a photographer and have lots of photos (this is an example from my life!). You might organize them by the people that appear in them, because sometimes people ask you for photos of them. But you might also want to organize them by the location and by the date. There's no real way to nest these three things as they're totally separate axes of organization. So you can create three different hierarchies for these three different things and have each photo present in all three, without having to store each photo three times. That's the magic of hardlinks. Unlike symlinks, we don't need to worry about where the "real file" is, because they're all the real file. We can delete and move at will because the file will be retained until there are no longer any references to it, and removed when you delete the last hardlink. It's simple and doesn't require you to keep track of very much.

Best Answer

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Linux – How to recover open but deleted file on Linux using ln instead of cp

Linux – When would creating a hard link be useful

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