Re: Portability of "mv -f"

[Eric Siegerman]

On Thu, Sep 21, 2000 at 02:25:47PM -0700, Ian Lance Taylor wrote:
>    Date: Thu, 21 Sep 2000 06:50:43 -0400 (EDT)
>    From: Pavel Roskin <address@hidden>
> 
>    how portable is "mv" across mount points, i.e. between
>    $TMPDIR and the current directory? Will "mv -f" help?
> 
> I do not think that mv across mount points is portable.  The -f option
> will not help.

Moving individual files between filesystems should be extremely
portable; I'm pretty sure V6 could do this.  Not atomic, though,
which bit us recently (when doing "mv newfile existingfile",
there's a critical section where neither the old nor the new
version of existingfile actually exists -- not nice if the file
in question is your (semi-dynamic) home page...)

I very much doubt that V6 could handle directories, though.  I'm
not sure how portable this is, but I'd be willing to bet its
portability closely correlates with that of "cp -r" :-)

--

|  | /\
|-_|/  >   Eric Siegerman, Toronto, Ont.        address@hidden
|  |  /
Nobody ever got fired for buying Microsoft -- but they could get
fired for relying on Microsoft.
        - Chris Garrigues
>From address@hidden  Sun Sep 24 13:54:35 2000
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Date: Sun, 24 Sep 2000 15:29:51 +1100 (EST)
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Subject: address@hidden proposal for autoconf languages
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From: mike burrell <address@hidden>
Sender: "mike burrell,,," <address@hidden>
To: address@hidden
Subject: proposal for autoconf languages
Date: Sat, 23 Sep 2000 17:30:30 -0600

i've been trying to wrap autoconf around one of my projects (in progress). 
the problem is that my project relies heavily on Objective C.  as i'm sure
you know, there is no AC_LANG_OBJC macro :).  i'm finding that for Objective
C related things, i'm needlessly reimplementing some of the already existing
macros, e.g. AC_TRY_COMPILE.

rather than proposing AC_LANG_OBJC (which actually wouldn't be too hard),
i'm proposing an AC_LANG_CUSTOM.  syntax might look like so:

        AC_LANG_CUSTOM(language-name, extension[, compiler[, flags[,
                cross]]])

which, in my case, might look something like:
        AC_LANG_CUSTOM(Objective C, m, $OBJCC, $OBJCFLAGS)
or maybe
        AC_LANG_CUSTOM(Objective C, m, gcc)
or something to that effect.

example (beginnings of) code might look something like:

dnl AC_LANG_CUSTOM()
AC_DEFUN(AC_LANG_CUSTOM,
[define([AC_LANG], $1)dnl
ac_ext=$2
ac_compile='$3 -c $4 $CPPFLAGS conftest.$ac_ext 1>&AC_FD_CC'
ac_link='$3 -o conftest${ac_exeext} $4 $CPPFLAGS $LDFLAGS conftest.$ac_ext 
$LIBS 1>&AC_FD_CC'
cross_compiling=$5
])

which i've patterned after AC_LANG_C

there are still some things i have yet to figure out: how this would work
with LANG_SAVE and LANG_RESTORE; how to intelligently search for a compiler
(analogous to AC_PROG_CC).

quite frankly i was hoping that you (or someone you know) might have time to
think about this and/or start implementing it.  i have a few projects that
i'm working on already that i would like to finish first.  if you need to
discuss it more or want me to provide some trivial code, then i can do that,
so long as i don't have to do something that's going to take me days to do
:).  i just thought about it a bit this afternoon and there's nothing about
it to me that immediately makes it seem impractical.  personally, i think
this would be a much cleaner solution than having a myriad of AC_LANG_*.

cheers

-- 
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