POSIX and symbolic links ????

POSIX and symbolic links ????

[Fredrik Olsson]

How does one check if a file is a symbolic link?
There seems to be no functionality in the POSIX Ada bindings
to do this...

Thanks,
Fredrik

-- 
  Fredrik Olsson             EMAIL: frol@celsiustech.se
  Celera AB                  PHONE: +46 8 580 851 21
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Re: POSIX and symbolic links ????

[Robert Dewar]

In a way it is a shame if a program *can* detect a symbolic link, because
then it means that symbolic links would not be transparent, and the great
attraction of this facility is precisely the transparency.

Re: POSIX and symbolic links ????

[Richard Kenner]

In article <39jgdi$bsq@gnat.cs.nyu.edu> dewar@cs.nyu.edu (Robert Dewar) writes:
>In a way it is a shame if a program *can* detect a symbolic link, because
>then it means that symbolic links would not be transparent, and the great
>attraction of this facility is precisely the transparency.

No, it's only important that the standard ways of accessing files
handle symbolic links transparently.  There's no problem in providing
a separate mechanism that can be used to see if a file is a symbolic
link.  You clearly need such a thing.  If you didn't how would "ls" work
and display the link?  There are other programs, such as tar, that have
a legitimate reason to know.  Also, other similar file maintenance-type
programs such as "du".

Re: POSIX and symbolic links ????

[David Emery]

The problem is that symbolic links are not part of POSIX.1.  They're
included in the POSIX.1a supplement, for which there is no equivalent
Ada binding.  

But look at the C documentation for the system call lstat(), which I
think is included in the POSIX.1a system calls.  To quote from the man
page on my Sun:

     lstat() is like stat() except in the case  where  the  named
     file  is  a  symbolic  link,  in  which case lstat() returns
     information about the link, while stat() returns information
     about the file the link references.

Note that using symbolic links in a way that is visible to the program
is not POSIX.5-compliant.

				dave
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