Comment by bariumbitmap

1 day ago

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.

https://man.openbsd.org/cp

5 comments

bariumbitmap

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rakel_rakel  2 hours ago

You can see it in the code, lstat vs stat and copy_special, copy_fifo vs copy_file. They'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

embedding-shape  1 day ago

> 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 "regular" and not "special" file.

  • rezonant  1 hour ago

    Only clear to those with a heavy UNIX background-- I understood and correctly interpreted it on first read, but the concept of a "regular file" 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.