How to catch mount events on Linux?

Question

I want to somehow get notified if a mount or unmount occurs for a USB drive.

At the moment I use udev and then wait for x seconds for a new entry in /proc/mounts. This works ok if the mounting is automatic. However this won't work if the user unmounts/mounts the device manually.

Is there a way to catch those events?

Answer 1

If polling is okay you could look at the time on mtab:

import time, os
last = None
current = None

for x in range(0,60):
    if last == current:
        current = os.stat('/etc/mtab').st_mtime
        print('Current Updated: ', current)
        print('No Changes...')
    else:
        last = current
        print('Last Updated: ',last)
        print('Something was mounted or unmounted')
    time.sleep(1)

You could also use filecmp or difflib to see if there are any changes, and parse what kind of changes occurred if you go with this route.