inotify

With inotify, you can efficiently watch your filesystem for changes and run commands based on the results.

You can get your current inotify file watch limit by executing:

$ cat /proc/sys/fs/inotify/max_user_watches

You may need to increase the number of files one user can watch with inotify. Many distributions have a default limit of 8192 watched files per user. The maximum amount is 524288. You can set a new limit temporary with:

$ sudo sysctl fs.inotify.max_user_watches=524288
$ sudo sysctl -p

To make it permanent, store it in the sysctl config file.

/etc/sysctl.d/40-max-user-watches.conf

fs.inotify.max_user_watches=524288

On Arch Linux, Fedora and other RPM-based distributions, you apply this with sudo sysctl –system. On Debian, Ubuntu and many other systems, this has to be in /etc/sysctl.conf and you apply it with sudo sysctl -p.

You may also need to pay attention to the values of fs.inotify.max_queued_events and fs.inotify.max_user_instances if watching is slow or hangs.

(source)

Non-exhaustive list of programs which use inotify to watch for changes and may have problems with restrictive limits:

• Syncthing
• Visual Studio Code