gnome-presence

This is a little Python script which runs scripts in your home directory when your computer becomes idle (e.g. when screensaver is about to kick in), when it becomes active again (when you move the mouse or otherwise stop the screensaver and/or unlock it), and in either of these cases.

This was written because of GNOME's perplexing decision to remove the very useful gnome-screensaver-command program which could be used in shell scripts to perform actions when the computer was becoming idle, such as pausing music, or in my case, telling BOINC that it can go crazy with my GPUs, and pause the GPU jobs when I return to my computer again (a feature which is part of BOINC, but broken for me).

Installing

This software assumes you're running a new-ish version of GNOME 3, on a UNIX OS which has Python installed and the requisite dbus and GObject introspection Python libraries already installed -- Fedora 26, the distro I tested this on, comes with all these out of the box, and I assume so do all other Linux distributions which come with the GNOME 3 desktop environment.

Run the command:

sudo python setup.py install

Now you'll have gnome-presence globally installed to /usr/bin on your system.

Running

By default, gnome-presence runs silently and indefinitely:

$ gnome-presence

To make it chattier:

$ gnome-presence -v

You can also get it to wait for an idle/active event and then quit ("one-shot" mode):

$ gnome-presence -o

Combining this with --no-scripts/-n, you can use it simply to wait for an event to happen:

$ gnome-presence -o -n

If you wanted to wait until a user comes back in a shell script:

$ gnome-presence -o -n -e active

If you want it to tell you what event it's received, you can set --output-format/-f:

$ gnome-presence -f '{state}: {state_id}'

Which would give you output like:

active: 0
idle: 3
active: 0
idle: 3

Script directories

By default, it will look in these directories:

• ~/.local/gnome-presence/idle.d
• ~/.local/gnome-presence/active.d
• ~/.local/gnome-presence/both.d

Any files you put in those directories need to be made executable in order for it to run them.

You can make it look in different directories with command line arguments: --idle-dir, --active-dir and --both-dir.

If you want it to run your active scripts when you first start the program, pass it --active-on-start.

Script environment

The running scripts are given an extra environment variable, PRESENCED_STATE. That describes what state the session is in. It will be one of active, idle or both.

gnome-presence spawns the processes but does not wait for them, nor does it kill them if itself quits. If you have any long running processes you should make sure to stop them yourself. You can make it wait for the spawned processes to end upon exit with --wait-on-exit.

If you want it to stop or kill processes spawned at the previous event, you can pass it --stop-processes and --kill-processes. It tries to stop them normally first, and then if --kill-processes is specified it waits a number of seconds specified by --kill-timeout (default: 5 seconds) and then sends them the KILL signal.

Behind the scenes

It's using the Python DBus interface to listen to signals from org.gnome.SessionManager.Presence. When Gnome starts to fade your screen to black, and when you do something to come back from screensaver like moving your mouse, it emits a DBus signal at org.gnome.SessionManager.Presence.StatusChanged, with an integer value. A value of 0 is active (user is present), any other value is idle (session is idle). So far I've only seen it alternate between 0 and 3 but possibly other values exist for other states like user switching or screen locking.