According to man 5 magic:
"The file /usr/share/misc/magic specifies what patterns are to be tested for, what message or MIME type to print if a particular pattern is found, and additional information to extract from the file."
So I went looking for that file:
$ file /usr/share/misc/magic /usr/share/misc/magic: symbolic link to `../file/magic' $ ll /usr/share/file/magic total 8 drwxr-xr-x 2 root root 4096 2011-08-08 13:52 ./ drwxr-xr-x 3 root root 4096 2011-10-12 07:27 ../ So it would appear that the file specified in the man page is in fact a symbolic link to a directory which is empty. Where is that file on my Ubuntu 11.10 system?
The reason I want to look at it is that both the file --mime command and the python magic module are returning the same incorrect mime types for some files, and I'd like to see the format of that file so I can modify the relevant associations responsibly. Thanks.
UPDATE:
Thanks to @Caesium for pointing me to the strace command. Piping the output from that to grep magic, I got the following output:
open("/usr/lib/libmagic.so.1", O_RDONLY) = 3 access("/home/phoenix/.magic", R_OK) = -1 ENOENT (No such file or directory) open("/etc/magic.mgc", O_RDONLY) = -1 ENOENT (No such file or directory) stat("/etc/magic", {st_mode=S_IFREG|0644, st_size=111, ...}) = 0 open("/etc/magic", O_RDONLY) = 3 open("/usr/share/misc/magic.mgc", O_RDONLY) = 3 So it would seem that file first looks in /home/username/.magic, then /etc/magic.mgc, then /etc/magic, and finally in /usr/share/misc/magic.mgc to determine file types. This suggests that the proper place to add user-specific association rules is in /home/username/.magic, and system-wide rules in /etc/magic. I chose the latter option.
For the record, here are my additions to /etc/magic:
# python: file(1) magic for python modules and scripts 0 string """ a python script text executable !:mime text/x-python 0 regex #!\ .*\ python a python script text executable !:mime text/x-python # pyc file: first four bytes are magic number # which changes with each python version. # this is for version 2.7.2: 0 belong 0x03f30d0a python compiled !:mime application/x-python-bytecode The man page for magic discourages the use of "regex" (for performance reasons), but I thought that this would be the simplest option for me. I hope this helps others solve this problem, should they run into it--the files which are now detected as text/x-python were previously identified as text/x-java by libmagic, which seemed frankly ridiculous.
1 Answer
You were almost there; it's in /usr/share/file/magic.mgc:
$ file /usr/share/file/magic.mgc /usr/share/file/magic.mgc: magic binary file for file(1) cmd (version 7) (little endian) As a slight aside, I actually found this just by looking around a bit, but you can prove it's actually using that file via strace:
$ strace file / <snip lots of output> open("/usr/share/misc/magic.mgc", O_RDONLY) = 3 <snip a bit more output> /usr/share/misc/magic.mgc is just yet another symlink. I guess the manpage is out of date.
