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Re: A "current directory" concept for Java...

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Martin Gregorie <martin@address-in-sig.invalid> wrote:
> On Fri, 22 Aug 2014 16:49:12 +0000, Andreas Leitgeb wrote:
>> I'm fully aware, that the concept of a mutable "current directory" for
>> the whole VM does not work at all well with threads, and thus there is
>> of course no such thing like "System.chDir(...)" in Java.
> Unless I missed something, on a Unix/Linux system the Java 'current 
> directory' is the directory in $PWD when the JVM is started and all 
> relative filenames are relative to $PWD.

That's typically the initial value for the "current directory."
In most languages this can be changed lateron, and in some of
those other languages this interferes badly with threads, which
I believe is the reason, why Java doesn't allow it to be changed
lateron.

> I filename os
"A filename is ..." ?
>                relative unless it 
> starts with '/'. Isn't it the same on a Windows box except that an 
> absolute name will start with a drive designator?

Well, you already named the first exception: drive letters...
Old MacOS (pre-X) had relative paths start with the separator char ":"
and had no special name to denote "parent" at all (but fortunately,
that's mere archaeology by now).

Since writing my previous post, I've found that the non-trivial parts
of what I sought for already exist as Path.resolve().
<http://docs.oracle.com/javase/7/docs/api/java/nio/file/Path.html#resolve(java.lang.String)>
Now, all left to do for a chDir is:  curDir = curDir.resolve(relOrAbsPath);
(and maybe curDir = curDir.toRealPath();)

> Apart from that, anything else I've needed can be achieved by judicious 
> use of the File class. At least, that's been my experience and I've 
> written command line Java programs that walk directory structures 
> examining the files and directories they find there and applying 
> appropriate actions.

I'll need to emulate some kind of current directory, and will need to
manually join user-provided relative paths (typically bare filenames)
to that current directory for various uses (open,remove,rename,...).
Eventually I need to spawn processes, which then need that emulated
current directory to be their initial real current directory.

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A "current directory" concept for Java... Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-22 16:49 +0000
  Re: A "current directory" concept for Java... Jeff Higgins <jeff@invalid.invalid> - 2014-08-22 14:50 -0400
  Re: A "current directory" concept for Java... Jeff Higgins <jeff@invalid.invalid> - 2014-08-22 15:10 -0400
  Re: A "current directory" concept for Java... Martin Gregorie <martin@address-in-sig.invalid> - 2014-08-22 19:26 +0000
    Re: A "current directory" concept for Java... Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-22 23:38 +0000
      Re: A "current directory" concept for Java... Martin Gregorie <martin@address-in-sig.invalid> - 2014-08-23 14:24 +0000
        Re: A "current directory" concept for Java... Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-23 16:31 +0000
          Re: A "current directory" concept for Java... Martin Gregorie <martin@address-in-sig.invalid> - 2014-08-23 19:34 +0000
            Re: A "current directory" concept for Java... Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-24 08:42 +0000
              Re: A "current directory" concept for Java... Martin Gregorie <martin@address-in-sig.invalid> - 2014-08-24 10:37 +0000
                Re: A "current directory" concept for Java... Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-24 13:41 +0000
                Re: A "current directory" concept for Java... Martin Gregorie <martin@address-in-sig.invalid> - 2014-08-24 18:33 +0000
                Re: A "current directory" concept for Java... Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-24 22:33 +0000
                Re: A "current directory" concept for Java... Martin Gregorie <martin@address-in-sig.invalid> - 2014-08-25 00:14 +0000
  Re: A "current directory" concept for Java... Jeff Higgins <jeff@invalid.invalid> - 2014-08-22 19:45 -0400
    Re: A "current directory" concept for Java... Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-23 15:32 +0000
      Re: A "current directory" concept for Java... Jeff Higgins <jeff@invalid.invalid> - 2014-08-23 12:49 -0400
      Re: A "current directory" concept for Java... Jeff Higgins <jeff@invalid.invalid> - 2014-08-23 17:40 -0400
  Re: A "current directory" concept for Java... Jan Burse <janburse@fastmail.fm> - 2014-08-23 10:31 +0200
    With new Path (Re: A "current directory" concept for Java...) Jan Burse <janburse@fastmail.fm> - 2014-08-23 10:48 +0200
      Re: With new Path (Re: A "current directory" concept for Java...) Andreas Leitgeb <avl@auth.logic.tuwien.ac.at> - 2014-08-23 14:38 +0000
  Re: A "current directory" concept for Java... Roedy Green <see_website@mindprod.com.invalid> - 2014-08-23 05:31 -0700

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