[COFF] [TUHS] Re: History of cal(1)?

[Theodore Ts'o via COFF]

On Fri, Sep 26, 2025 at 08:21:20PM -0400, Dan Cross via COFF wrote:
> 
> If you tried to inline file data into a directory, on the other hand....
>

Something quite interesting (to me, anyway :-) is the inclusion of
*metadata* into the directory entry; specifically, d_type, since while
you can change the file permission, you can't change a symlink to a
regular file or directory, and this can significantly speed up
operations like "find . -type f -name .[a-z]*".

Chris Siebenmann has a very nice write up the history here[1]; I
didn't realize that it didn't show up until BSD 4.4, albeit
undocuimented, and did't show up as a documented interface until 1997
in FreeBSD, with Linux picking it up in 2001, and Solaris picking it
up.... never.  (Although ZFS maintains the information on-disk, even
though Solaris didn't have a way of taking avantage of the d_type
field.)

[1] https://utcc.utoronto.ca/~cks/space/blog/unix/DirectoryDTypeHistory

						- Ted