5 ms·

The /sbin/init binary is hard linked to /sbin/dashboard, /sbin/poweroff, /sbin/shutdown, and /sbin/wrapperd. While this technically is 5 files, it’s a single fi

The /sbin/init binary is hard linked to /sbin/dashboard, /sbin/poweroff, /sbin/shutdown, and /sbin/wrapperd. While this technically is 5 files, it’s a single file hard linked 4 times to provide convenience commands. Err, that's definitely 1 file with 5 directory entries, not 5 files.

titanomachy 3y ago
Wonder why they would use hard links instead of symlinks. Edit: interesting, seems like there's a mild performance benefit. https://unix.stackexchange.com/a/20716 https://unix.stackexchange.com/a/20716
- 0xbadcafebee 3y ago
  There's a lot of benefits actually, as symbolic links often need to be handled as a completely different type of file with different semantics which often leads to bugs. Hard links are always better when you know you are dealing with a single static host & filesystem. Symbolic links in such a case are only better for indicating quickly to the user which files are linked to which others.
- vundercind 3y ago
  Reverse question: why use symlinks when you can get away with hard links?
  - AtlasBarfed 3y ago
    Main thing I've seen with hard links is that deletions delete the source file which about 90% of the time isn't what an end user wants
    - whartung 3y ago
      Only if its the last hard link. If nothing else, its a wee bit of insurance from deletion since no single link removal should remove the file. Anecdote, eons ago, we had a problem where the vendor needed to log in to the machine with the intent that they were going to upload some utilities, fix a problem, and then delete them. Before I let them in, I set up a script that constantly scanned the directory tree they were in, and hard linked everything so I could look at what they were using later.
      - cpach 3y ago
        Clever solution!
    - rcxdude 3y ago
      that isn't generally how hardlinks work: you need to delete all instances of it to delete the file, as opposed to having one 'real' file like with symlinks.
    - wizzwizz4 3y ago
      That's a problem with directory hardlinks: a recursive deletion will wipe the directory (in the same way that truncate will destroy a file regardless of how many hardlinks it has). But we don't usually allow directory hardlinks these days.
    - wakawaka28 3y ago
      It's more of a problem that changes to one linked file change the only copy. But this depends on your filesystem. Not all work this way.
  - jesse9766 3y ago
    Hard links only work in the same filesystem. If your system only has one volume with one filesystem (e.g. a PC) that's fine, but not a very portable option for servers.
    - hn92726819 3y ago
      Every one of those files is in /sbin though
- cpach 3y ago
  Not sure it really matters that much in this case. But why not? Hard links are a quite clean and simple concept. One “object”, multiple names.

titanomachy 3y ago

Wonder why they would use hard links instead of symlinks. Edit: interesting, seems like there's a mild performance benefit. https://unix.stackexchange.com/a/20716 https://unix.stackexchange.com/a/20716

0xbadcafebee 3y ago
There's a lot of benefits actually, as symbolic links often need to be handled as a completely different type of file with different semantics which often leads to bugs. Hard links are always better when you know you are dealing with a single static host & filesystem. Symbolic links in such a case are only better for indicating quickly to the user which files are linked to which others.
vundercind 3y ago
Reverse question: why use symlinks when you can get away with hard links?
- AtlasBarfed 3y ago
  Main thing I've seen with hard links is that deletions delete the source file which about 90% of the time isn't what an end user wants
  - whartung 3y ago
    Only if its the last hard link. If nothing else, its a wee bit of insurance from deletion since no single link removal should remove the file. Anecdote, eons ago, we had a problem where the vendor needed to log in to the machine with the intent that they were going to upload some utilities, fix a problem, and then delete them. Before I let them in, I set up a script that constantly scanned the directory tree they were in, and hard linked everything so I could look at what they were using later.
    - cpach 3y ago
      Clever solution!
  - rcxdude 3y ago
    that isn't generally how hardlinks work: you need to delete all instances of it to delete the file, as opposed to having one 'real' file like with symlinks.
  - wizzwizz4 3y ago
    That's a problem with directory hardlinks: a recursive deletion will wipe the directory (in the same way that truncate will destroy a file regardless of how many hardlinks it has). But we don't usually allow directory hardlinks these days.
  - wakawaka28 3y ago
    It's more of a problem that changes to one linked file change the only copy. But this depends on your filesystem. Not all work this way.
- jesse9766 3y ago
  Hard links only work in the same filesystem. If your system only has one volume with one filesystem (e.g. a PC) that's fine, but not a very portable option for servers.
  - hn92726819 3y ago
    Every one of those files is in /sbin though
cpach 3y ago
Not sure it really matters that much in this case. But why not? Hard links are a quite clean and simple concept. One “object”, multiple names.