On Sunday 06 February 2011 23:58:50 Bob Proulx wrote: > Lisi wrote: > > 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. :-( > > Help us out. Can you phrase an example of what you want? Otherwise > the only magic number anyone can give you is 42. > > "Magic" is relative here. The file program simply looks at parts here > and parts there of the file and then makes a best-guess about it. The > magic file database in libmagic1 is a documentation of that best guess > effort. See the man page for information about the format of the > information there. > > man magic > > So for example most files don't have a single magic number. Most types > of files have many possible combinations. And when files are layered > it is more difficult such as a tar of script, or a gzip'd file that is > a tar of a script. The file program will quickly try to undo those > layers and make a guess. It isn't perfect. > > Since the file program tries to work across any possibility in the > universe it has a very hard task. If you have a more restricted set > of input files you might be able to do better. > > For example '#!/' and #! /' denote scripts. Any file that starts with > the binary data 23 21 20 2f or 23 21 2f is almost certainly a shell > script. What type? For that you need to look further and see what > characters follow. > > Note that in Squeeze /usr/share/misc/magic is now an empty directory > instead of a file. The source isn't installed anymore. That is a > shame. For squeeze you will need to install the source package to get > to raw data that you can look at. > > apt-get source libmagic1 > cd file-5.04 > ls -log magic/Magdir/
Your questions and detailed analysis, and everyone else's answers, have answered my questions and teh penny has dropped. I was asking teh wrong question, which illustrates teh depth of my ignorance! So thank you very much indeed for taking so much trouble. You and teh others have turned a light on in my almost dark brain. Lisi -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/201102070655.30413.lisi.re...@gmail.com
