How to solve the Dropbox filesystem monitoring issue
Once Dropbox throws you an error that reads “Unable to monitor filesystem. Please run: echo 100000 | sudo tee /proc/sys/fs/inotify/max_user_watches
and restart Dropbox to correct the problem.” you’d better adjust settings in a system config file, to keep changes after reboot.
Open system config (as superuser, of course) in your favorite text editor
$ sudo vi /etc/sysctl.conf
add just one line of code to the end of the file:
fs.inotify.max_user_watches = 1048576
save the file (Shift-ZZ, if you are new to Vi), and reboot computer to apply settings and restart Dropbox.
If you, by any chance, spent the last couple of years living under a rock thus still don’t use Dropbox, create an account immidiately. You will get a regular 2GB free online storage, plus 250MB extra free space if you register via my referral link.