How to tell if an executable is 32-bit or 64-bit on x86-64?

[Jonathan Ryshpan]

On Sat, 2005-07-02 at 23:11 -0500, Jonathan Berry wrote:
> On 7/2/05, Jonathan Ryshpan <jonrysh at pacbell.net> wrote:
> > I have an x86-64 system and sometimes need to find out if a library or
> > executable is built for 32-bit or 64-bit execution.  On FC3,
> >         file foo.so
> > would produce a message that would do the job, like this:
> >         $ file usr/lib*/libssl3.so
> >         /usr/lib/libssl3.so:   ELF 32-bit LSB shared object, Intel 80386, version 1 (SYSV), stripped
> >         /usr/lib64/libssl3.so: ELF 64-bit LSB shared object, AMD x86-64, version 1 (SYSV), stripped
> > A similar command on FC4 produces something like this:
> >         $ file /usr/lib*/libssl3.so
> >         /usr/lib/libssl3.so:   data, stripped
> >         /usr/lib64/libssl3.so: data, stripped
> > which is not very useful.
> > 
> > What's the best thing to do: Copy FC3 /etc/magic into FC4?  Install the
> > latest file utility from the GNU fileutils?
> > 
> > I have submitted this as a bug to Red Hat Bugzilla.
> > 
> > jon
> 
> Strange, works-for-me:
> $ file /usr/lib*/libssl3.so
> /usr/lib64/libssl3.so: ELF 64-bit LSB shared object, AMD x86-64,
> version 1 (SYSV), stripped
> /usr/lib/libssl3.so:   ELF 32-bit LSB shared object, Intel 80386,
> version 1 (SYSV), stripped
> 
> $ file --version
> file-4.13
> magic file from /usr/share/file/magic
> 
> FC4 x86_64 running the latest FC kernel.

I seem to have led the list down the garden path.  I have a ~/.magic
file with these contents:
        $ cat .magic
        # From Caleb Epstein <cae at bkln.org>
        0       string  ajkg    Shorten compressed audio data
        >4      byte    >0      - version %d
        
This is to recognize audio files compressed with the shorten utility.

I also have an /etc/magic file with exactly the same contents.  The last
version of file (as I remember it) had a bug that /etc/magic didn't get
handled by file; so I put another copy of the test into ~/.magic.  The
new version of file seems to have the additional problem that a ~/.magic
file keeps the file utility from working properly.  This is such a mess
that it may be easier to find the bug than to describe it properly.

jon