Re: FYI: be careful to follow links during libltdl install [libtool--release--2.0--patch-51]

[Noah Misch]

On Wed, Mar 02, 2005 at 10:34:19AM +0000, Gary V. Vaughan wrote:
>    ## with libtoolize, we have to preserve their timestamps carefully:
>    install-data-local:
>       $(mkinstalldirs) $(DESTDIR)$(ltdldatadir)
>   -   ( cd $(srcdir) && $(AMTAR) cf - $(ltdldatafiles); ) \
>   +   ( cd $(srcdir) && $(AMTAR) chof - $(ltdldatafiles); ) \
>         | ( cd $(DESTDIR)$(ltdldatadir) && $(AMTAR) xf -; )

Why `o'?  On archive creation, that makes GNU and Tru64 tar produce a V7-style
tar archive; it means nothing to most tar programs.

On the other hand, the extraction invocation probably does need `o' to make Unix
tar reset file ownership (e.g., when an unprivileged user builds libtool and
then installs it as root).

One more consideration: tar copies the modes of the files, so the modes of the
installed files will depend on the umask of the user who unpacked the libtool
distribution.

BTW, why is `tar c | tar x' superior to `cp -Rp'?  Both have the same time stamp
truncation issues on GNU/Linux:

$ touch foo; mkdir dir
$ cp -p foo bar
$ tar cf - foo | (cd dir && tar xf -)
$ ls -l --time-style=full foo bar dir/foo
-rw-------    1 nm       nm              0 2005-03-02 20:49:10.000000000 -0500 
bar
-rw-------    1 nm       nm              0 2005-03-02 20:49:10.000000000 -0500 
dir/foo
-rw-------    1 nm       nm              0 2005-03-02 20:49:10.338929609 -0500 
foo

I do not know how it works out on other platforms.  It may also be the case that
newer coreutils `cp' copy time stamps to their full precision; I vaguely recall
something about that.