Re: [Documentation] -d returns true for symlink to directory

[Reuti]

> Am 21.07.2016 um 23:38 schrieb Bob Proulx <bob@proulx.com>:
> 
> Reuti wrote:
>> While we are on this: wondering about the difference about -h and -L I found 
>> that `man test` outputs on OS X:
>> 
>> "     -h file       True if file exists and is a symbolic link.  This 
>> operator is retained for compatibility with pre-
>>                   vious versions of this program. Do not rely on its 
>> existence; use -L instead."
>> 
>> while on Linux `man test` just states that it's the same. Is there any 
>> preference which one should be used for the bash builtin?
> 
> Originally Unix did not provide symlinks.  Then when symlinks were
> added they were not completely added in a uniform regular way through
> every command.  Bummer!
> 
> The original option letter used by test to check for the presence of a
> symlink was -h.  I don't know why.  But in those days the only test
> option to test for a symlink was -h.  The -L came later.  This legacy
> is still visible in the HP-UX test man page for example.  No -L
> documented there.
> 
>  http://nixdoc.net/man-pages/HP-UX/man1/test.1.html
> 
> However note that because POSIX requires it the /bin/sh posix shell
> must implement -L as identical to -h.  And the reverse.  Therefore you
> are safe to use either on any POSIX system.  Remember too that POSIX
> wasn't originally meant as a design document but as an OS feature
> non-proliferation treaty to make it possible to write portable
> programs.  POSIX features must be present on any POSIX system and
> therefore you can use the feature and expect it to work.

Thx for this historical digest.

-- Reuti


> If you need to interact with legacy systems which predate POSIX and
> have never been updated to comply then you must use -h because that is
> all there is there.  But if you never interact with anything non-POSIX
> then using -L is okay too.  Either is the same as the other now.
> 
> I think the statement in the Apple man page is there because someone
> liked -L over -h and wanted to scare everyone into using one over the
> other.  But there isn't any reason to do so.
> 
> Bob
>