Python - Check if linux partition is read-only or read-write?

Question

I have a python application running on a beaglebone. How do I (in Python) check if the "/mnt" partition is mounted as read-only or read-write?

Answer 1

EDIT: The answer makes the assumption that you plan to write to /mnt.

I would just try to write to it and catch OSError exception to handle the read-only case.

Answer 2

This should do the trick for you:

def isMountReadonly(mnt):
    with open('/proc/mounts') as f:
        for line in f:
            device, mount_point, filesystem, flags, __, __ = line.split()
            flags = flags.split(',')
            if mount_point == mnt:
                return 'ro' in flags
        raise ValueError('mount "%s" doesn\'t exist' % mnt)

print "read only: %s" % isMountReadonly('/mnt')

Output:

read only: False

Answer 3

Solution is pretty much trivial, with only 1 syscall (statvfs).

stat = os.statvfs('/mnt')

# Python < 3.2
ST_RDONLY = 1
readonly = bool(stat.f_flag & ST_RDONLY)

# Python >= 3.2
readonly = bool(stat.f_flag & os.ST_RDONLY)