Thread

1. bariumbitmap · 1791028825 · focus · HN ↗

   This blog post is odd because it keeps on hinting about a difference between `-r' and `-R' and links to the source code but never actually says what it is. I'll quote the OpenBSD manual that the post mentions but does not link to for some reason:

   > Historic versions of the cp utility had an -r option. This implementation supports that option; however, its use is strongly discouraged, as it does not correctly copy special files, symbolic links or FIFOs.

   <a href="https:&#x2F;&#x2F;man.openbsd.org&#x2F;cp" rel="nofollow">https:&#x2F;&#x2F;man.openbsd.org&#x2F;cp

   1. embedding-shape · 1791031096 · focus · HN ↗

      &gt; links to the source code but never actually says what it is.

      The snippet of code makes it very clear what the difference is, no?

      flag_copy_as_regular = 1 VS flag_copy_as_regular = 0, where regular would be a &quot;regular&quot; and not &quot;special&quot; file.

      1. maxlin · 1791146881 · focus · HN ↗

         Nope. That variable name could mean anything
      2. Modified3019 · 1791148736 · focus · HN ↗

         I have no idea what that means, or what the consequences would be for choosing one or the other.
      3. rezonant · 1791150854 · focus · HN ↗

         Only clear to those with a heavy UNIX background-- I understood and correctly interpreted it on first read, but the concept of a &quot;regular file&quot; is a bit in the wonk territory for most users, though the implication on symbolic links is a very practical one that surely lead to the removal (in the implementations where it was removed) of this option, since its very surprising that copying a directory heirarchy would cause symbolic links to become copies of what they linked to, instead of remaining symbolic links in the resulting directory.
      4. wodenokoto · 1791171087 · focus · HN ↗

         That’s for gnu implementation. For the BSD implementation author just links to the source code.
   2. rakel_rakel · 1791149309 · focus · HN ↗

      You can see it in the code, lstat vs stat and copy_special, copy_fifo vs copy_file. They&#x27;re all in utils.c.

      from the lstat man page:

           The lstat() function is identical to stat() except when the named file is
           a symbolic link, in which case lstat() returns information about the link
           itself, not the file the link references.
      

      symbolic link example:

          $ tree test1
          test1
          |-- file.txt
          `-- link.txt -> ../link.txt
      
          0 directory, 2 files
      
          $ cp -r test1 test2
          $ tree test2
          test2
          |-- file.txt
          `-- link.txt
      
          0 directory, 2 files
      
          $ cp -R test1 test3
          $ tree test3
          test3
          |-- file.txt
          `-- link.txt -> ../link.txt
      
          0 directory, 2 files
      

      For posterity, -R with added -L

          $ cp -RL test1 test4
          $ tree test4/
          test4/
          |-- file.txt
          `-- link.txt
      
          0 directory, 2 files

Unofficial Hacker News client; not affiliated with Y Combinator.