About HOME in OS X

About HOME in OS X

[Xue Fuqiao]

Hi list,

On my system (OS X 10.8.4):

  ELISP> (getenv "HOME")
  "/Users/xfq"
  ELISP> (expand-file-name "$HOME/foo")
  "/Users/xfq/emacs-repo/bzr/trunk/nextstep/Emacs.app/Contents/MacOS/$HOME/foo"

I'm confused here.  Why don't the result of two evaluations be the same?


--
Best regards, Xue Fuqiao.

Re: About HOME in OS X

[Xue Fuqiao]

On Tue, Jun 11, 2013 at 7:22 PM, Xue Fuqiao <xfq.free@gmail.com> wrote:
> Hi list,
>
> On my system (OS X 10.8.4):
>
>   ELISP> (getenv "HOME")
>   "/Users/xfq"
>   ELISP> (expand-file-name "$HOME/foo")
>   "/Users/xfq/emacs-repo/bzr/trunk/nextstep/Emacs.app/Contents/MacOS/$HOME/foo"
>
> I'm confused here.  Why don't the result of two evaluations be the same?

Hmm... The following expression works properly:
  (expand-file-name (substitute-in-file-name "$HOME/foo"))

--
Best regards, Xue Fuqiao.

Re: About HOME in OS X

[Eli Zaretskii]

> Date: Tue, 11 Jun 2013 19:27:46 +0800
> From: Xue Fuqiao <xfq.free@gmail.com>
> 
> On Tue, Jun 11, 2013 at 7:22 PM, Xue Fuqiao <xfq.free@gmail.com> wrote:
> > Hi list,
> >
> > On my system (OS X 10.8.4):
> >
> >   ELISP> (getenv "HOME")
> >   "/Users/xfq"
> >   ELISP> (expand-file-name "$HOME/foo")
> >   "/Users/xfq/emacs-repo/bzr/trunk/nextstep/Emacs.app/Contents/MacOS/$HOME/foo"
> >
> > I'm confused here.  Why don't the result of two evaluations be the same?

Could be a symlink or something similar?

Re: About HOME in OS X

[Barry Margolin]

In article <mailman.1403.1370966034.22516.help-gnu-emacs@gnu.org>,
 Eli Zaretskii <eliz@gnu.org> wrote:

> > Date: Tue, 11 Jun 2013 19:27:46 +0800
> > From: Xue Fuqiao <xfq.free@gmail.com>
> > 
> > On Tue, Jun 11, 2013 at 7:22 PM, Xue Fuqiao <xfq.free@gmail.com> wrote:
> > > Hi list,
> > >
> > > On my system (OS X 10.8.4):
> > >
> > >   ELISP> (getenv "HOME")
> > >   "/Users/xfq"
> > >   ELISP> (expand-file-name "$HOME/foo")
> > >   "/Users/xfq/emacs-repo/bzr/trunk/nextstep/Emacs.app/Contents/MacOS/$HOME
> > >   /foo"
> > >
> > > I'm confused here.  Why don't the result of two evaluations be the same?
> 
> Could be a symlink or something similar?

No, it just means that he did it while his current directory was 
/Users/xfq/emacs-repo/bzr/trunk/nextstep/Emacs.app/Contents/MacOS. 
"$HOME/foo" is a relative path, so it's appended to the current 
directory.

As someone else pointed out, expand-file-name doesn't expand environment 
variables.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

Re: About HOME in OS X

[Peter Dyballa]

Am 11.06.2013 um 18:45 schrieb Barry Margolin:

> "$HOME/foo" is a relative path

$HOME is a variable that holds an *absolute* path. (It starts with "/", the root of the file system.)

--
Greetings

  Pete

               (This space left blank for technical reasons.)

Re: About HOME in OS X

[Barry Margolin]

In article <mailman.1410.1370970844.22516.help-gnu-emacs@gnu.org>,
 Peter Dyballa <Peter_Dyballa@Web.DE> wrote:

> Am 11.06.2013 um 18:45 schrieb Barry Margolin:
> 
> > "$HOME/foo" is a relative path
> 
> $HOME is a variable that holds an *absolute* path. (It starts with "/", the 
> root of the file system.)

But you carefully snipped the part where I pointed out that 
expand-file-name doesn't do variable substitution. So it's not a 
variable, it's a relative pathname that begins with the literal string 
"$HOME". That's why the result ends with "$HOME/foo" -- nothing was 
substituted.

-- 
Barry Margolin, barmar@alum.mit.edu
Arlington, MA
*** PLEASE post questions in newsgroups, not directly to me ***

Re: About HOME in OS X

[Peter Dyballa]

Am 11.06.2013 um 19:20 schrieb Barry Margolin:

> But you carefully snipped the part where I pointed out that 
> expand-file-name doesn't do variable substitution.

Because I did not understand that you meant it that way, that you meant the result and not your quotation "$HOME/foo" – which also started a new sentence.

--
Greetings

  Pete

The best way to accelerate a PC is 9.8 m/s²

Re: About HOME in OS X

[Thien-Thi Nguyen]

[-- Attachment #1: Type: text/plain, Size: 484 bytes --]

() Barry Margolin <barmar@alum.mit.edu>
() Tue, 11 Jun 2013 12:45:09 -0400

   As someone else pointed out, expand-file-name doesn't expand
   environment variables.

environment is context, i.e., that which need not be said.
different lands, different forests, different hope, different dread.
floating high above the mess,
we share a sigh for VMS,
where dollar signs in search paths beckon (still!) to those who dare to tread.

-- 
Thien-Thi Nguyen
GPG key: 4C807502

[-- Attachment #2: Type: application/pgp-signature, Size: 197 bytes --]

Re: About HOME in OS X

[Kevin Montuori]

On Tue, Jun 11, 2013, at 7:22, Xue Fuqiao wrote:

>   ELISP> (getenv "HOME")
>   "/Users/xfq"
>   ELISP> (expand-file-name "$HOME/foo")
>   "/Users/xfq/emacs-repo/bzr/trunk/nextstep/Emacs.app/Contents/MacOS/$HOME/foo"
> 
> I'm confused here.  Why don't the result of two evaluations be the same?

Nothing in expand-file-name's documentation would lead me to expect it
to expand an environment variable (prefixed with $ or otherwise).  I
think what you probably want is (expand-file-name "~/foo").

k.

-- 
  Kevin Montuori
  montuori@gmail.com

Re: About HOME in OS X

[Peter Dyballa]

Am 11.06.2013 um 13:22 schrieb Xue Fuqiao:

> Hi list,
> 
> On my system (OS X 10.8.4):
> 
>  ELISP> (getenv "HOME")
>  "/Users/xfq"
>  ELISP> (expand-file-name "$HOME/foo")
>  "/Users/xfq/emacs-repo/bzr/trunk/nextstep/Emacs.app/Contents/MacOS/$HOME/foo"
> 
> I'm confused here.  Why don't the result of two evaluations be the same?


This must be a failure on Mac OS X – I see it too in GNU Emacs of some 23.x and 24.x versions and variants… But wait! What is the documentation saying?

	Convert filename NAME to absolute, and canonicalize it.
	Second arg DEFAULT-DIRECTORY is directory to start with if NAME is relative
	(does not start with slash or tilde); if DEFAULT-DIRECTORY is nil or missing,
	the current buffer's value of `default-directory' is used.
	NAME should be a string that is a valid file name for the underlying
	filesystem.

So this is *not* a function or function that deals with some shell's constructs. "$HOME" is such a thing.

--
Greetings

  Pete

Every instructor assumes that you have nothing else to do except study for that instructor's course. 
				– Fourth Law of Applied Terror