[Q] get device major/minor number

[Thomas Portmann]

Hello all,

In a script I would like to extract all device infos from block or
character device. The "stat" function gives me most of the infos
(mode, timestamp, user and group id, ...), however I did not find how
to get the devices major and minor numbers. Of course I could do it by
calling an external program, but is it possible to stay within python?

In the example below, I would like to get the major (8) and minor (0,
1, 2) numbers of /dev/sda{,1,2}. How can I get them?

u...@host:~$ ls -l /dev/sda /dev/sda1 /dev/sda2
brw-rw 1 root disk 8, 0 Nov 30 19:10 /dev/sda
brw-rw 1 root disk 8, 1 Nov 30 19:10 /dev/sda1
brw-rw 1 root disk 8, 2 Nov 30 19:10 /dev/sda2
u...@host:~$ python3.1 -c 'import os
for el in ["","1","2"]: print(os.stat("/dev/sda"+el));'
posix.stat_result(st_mode=25008, st_ino=1776, st_dev=5, st_nlink=1,
st_uid=0, st_gid=6, st_size=0, st_atime=1291140641,
st_mtime=1291140640, st_ctime=1291140640)
posix.stat_result(st_mode=25008, st_ino=1780, st_dev=5, st_nlink=1,
st_uid=0, st_gid=6, st_size=0, st_atime=1291140644,
st_mtime=1291140641, st_ctime=1291140641)
posix.stat_result(st_mode=25008, st_ino=1781, st_dev=5, st_nlink=1,
st_uid=0, st_gid=6, st_size=0, st_atime=1291140644,
st_mtime=1291140641, st_ctime=1291140641)

Thanks


Tom
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Re: [Q] get device major/minor number

[Thomas Portmann]

On Tue, Nov 30, 2010 at 9:18 PM, Dan M  wrote:
> On Tue, 30 Nov 2010 21:09:14 +0100, Thomas Portmann wrote:

>> In the example below, I would like to get the major (8) and minor (0, 1,
>> 2) numbers of /dev/sda{,1,2}. How can I get them?
>
> I think the os.major() and os.minor() calls ought to do what you want.
>
>>>> import os
>>>> s = os.stat('/dev/sda1')
>>>> os.major(s.st_rdev)
> 8
>>>> os.minor(s.st_rdev)
> 1

Thank you very much Dan, this is exactly what I was looking for.


Tom
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