Re: [OT] Magic numbers

[Lisi <lisi.reisz@gmail.com>]

On Sunday 06 February 2011 22:01:33 Andrew M.A. Cater wrote:
> On Sun, Feb 06, 2011 at 09:13:59PM +0000, Lisi wrote:
> > On Sunday 06 February 2011 20:35:17 Eduardo M KALINOWSKI wrote:
> > > On 02/06/2011 06:27 PM, Lisi wrote:
> > > > I need to find out:
> > > > a)What the magic number should be for certain types of file and
> > > > b)Whether a specific file of that type has the correct magic number.
> > > >
> > > > Here is my one, so far futile, effort - in addition to googling until
> > > > I can see magic numbered smoke coming out of my ears. :-(
> > > >
> > > > lisi@Tux:~$ cat /usr/share/misc/magic.mgc | grep gzip
> > > > Binary file (standard input) matches
> > > > lisi@Tux:~$
> > > >
> > > > I realise that this is more specific to UNIX than specific to Debian
> > > > - but it applies to all the UNIX family, and Debian is part of that
> > > > family. ;-)
> > >
> > > That's a binary file, it won't help you much.
> > >
> > > See the corresponding source package, you should find the same
> > > information in that file in a more readable way.
> > >
> > >
> > > --
> > > "We shall reach greater and greater platitudes of achievement."
> > > 		-- Richard J. Daley
> > >
> > > Eduardo M KALINOWSKI
> > > eduardo@kalinowski.com.br
> >
> > Source code failed because I couldn't find the source code. The gzip that
> > I have is a Debian package, and no source code is offered.  BUT
> >
> > lisi@Tux:~$ cat /usr/share/misc/magic | grep gzip
> > # still uses gzip for the control.tar (first in the archive).  Only
> > #>84    string          gz              \b, uses gzip compression
> >
> > >>14    beshort 0x677a          (gzipped)
> > >>14    beshort !0x677a         (not gzipped)
> > >>36    belong&0x4      0x4             gzip
> >
> > # compress, gzip, pack, compact, huf, squeeze, crunch, freeze, yabba,
> > etc. # gzip (GNU zip, not to be confused with Info-ZIP or PKWARE zip
> > archiver) 0       string          \037\213        gzip compressed data
> > !:mime  application/x-gzip
> > 0       string          \037\236        frozen file 1.0 (or gzip 0.5)
> > # + gzipped tarball files
> >
> > >512    string          \037\213        \b, gzipped
> > >
> > >>0x2744        lelong  1               gzip compressed
> >
> > 0       string  llvc1   LLVM byte-codes, gzip compression
> > #>65    string          Gzip            (GNU gzip)
> > #>69    string          Gzip            (GNU gzip)
> >
> > >4      string          GZ              (gzip compressed)
> > >20    belong          2               gzipped
> >
> > lisi@Tux:~$
> >
> > So all I have to do now is a) interpret it and b) find the, hopefully
> > matching, code in a specific file!
> >
> >
> > Thanks for your help.
> >
>
> I find that running "file" on an unknown file may give me more or less
> usable information.
>
> GNU implementation of file "knows" some magic numbers and applies them to
> give a best guess as to what an unkown file is.

Thanks, Andy - yes, it told me what the files were, and its best guess was 
good.  (I should know - I created the files!) 

But no actual magic numbers. :-(

Thanks for your help.
Lisi

Lisi