7

I have a script that goes like this

ln /myfile /dev/${uniquename}/myfile

I want to remove the link of /dev/somename/myfile to decrease the link count.

How do I do this?

  • Your script will fail unless a /dev/${uniquename} directory already exists and /myfile and /dev/{uniquename}/. are on the same filesystem. – mosvy Aug 31 '19 at 14:04
13

TL;DR... just delete the file name you don't want (with rm).

If you create a hard link (which is what your command above is doing), you have two names pointing to the same area of storage. You can delete either name without affecting the other name or the storage - it's only when the last name is removed that the area of storage is released.

Compare this to soft links... created with ln -s - there, the link is different, it's a pointer to the original name rather than a pointer to the storage. If you delete the original named file the soft links point to something that has been deleted, so the link remains but is broken.

8

The command to remove a hard link is rm.

From the man page for rm:

Remove (unlink) the FILE(s).
1

I’m a little uncertain of your meaning, but I think your script creates /myfile as a hardlink to /dev/…/myfile and then you want to remove the latter.

If this is correct, instead of linking then removing the link, you could just move the file instead, producing the same result in a single command (mv) instead of two commands (ln and rm):

mv   /dev/…/myfile   /
0

Most existing answers advocate using rm. This is entirely correct, because you don't remove files: you remove links (and the file is removed when the last link pointing to it is removed, and the last open file descriptor is closed).

However, you should be aware of another utility too, unlink. It lacks the options of rm, and always has implicit -f option (sort of -- it will fail on a missing file, though). The benefit is that you can remove a file starting with a dash, at least in a theory...

...except you can't, if you use a Linux system, because the GNU crippled the unlink utility by adding command-line option support! So unlink -t does not remove a file named -t on a Linux system or any other system using the GNU coreutils.

(Yes, I know that rm -- -t or unlink -- -t works, no need to comment about that.)

  • I see there's some GNU fanboy downvoting me, and some BSD fanboy upvoting me, at the same time. – juhist Aug 31 '19 at 11:03
  • 3
    on Mac, unlink -f foobar gives usage: rm [-f | -i] [-dPRrvW] file ..., so it's not just GNU. Even if it was, so what? If you have filenames starting with dashes, you'll need to know to use -- or ./ at some point anyway, it doesn't help much if there's just one application that doesn't use command line options. – ilkkachu Aug 31 '19 at 11:26
  • Well, GNU and MacOS X both appear to be crippled then. The POSIX standard clearly states unlink has no options: pubs.opengroup.org/onlinepubs/9699919799/utilities/unlink.html – juhist Aug 31 '19 at 12:00
  • 1
    with that logic, almost all the GNU and BSD utils are "crippled", since they support options that aren't specified in POSIX. Note that it doesn't explicitly say that that implementation of unlink aren't allowed to have any options, like it does say for echo – ilkkachu Aug 31 '19 at 16:56
  • To add to ilkkachu's comment, the unlink utility, even though it's standard, is so obscure that OpenBSD doesn't even have it in its base system. – Kusalananda Sep 1 '19 at 7:57

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