My PC is on literally 24/7 as I run a FAH (Folding At Home) client and Transmission to seed the RPi and Ubuntu image torrents, but when I want to use my machine I have to pause them both as they bog the machine down.

This was a manual task I had to do every time I sat down and I had to remember to set them both going again when I was done, something I didn't always remember to do at 3AM after a session of "I'll just do a little more..."

Out of habit I lock my PC whenever I leave it and I thought that was an ideal trigger to pause/resume the FAH client and Transmission!

Listening For The Lock/Unlock Events

After spending a while trawling through many StackExchange and AskUbuntu questions, all from at least a year ago, for how to listen for the lock/unlock events I couldn't get anything to work. It didn't help that i'm using MATE and as I later found out it's MATE that emits the event...

Success!

After some guess work I managed to get it working based off this AskUbuntu question.

The key to it is the following line. Note I changed org.gnome.ScreenSaver to org.mate.ScreenSaver

dbus-monitor --session "type='signal',interface='org.mate.ScreenSaver'"

Output

When you run the dbus-monitor command above and you then lock then unlock your screen you'll get an output similar to this:

signal sender=org.freedesktop.DBus -> dest=:1.404 serial=2 path=/org/freedesktop/DBus; interface=org.freedesktop.DBus; member=NameAcquired
   string ":1.404"
signal sender=:1.29 -> dest=(null destination) serial=111 path=/org/mate/ScreenSaver; interface=org.mate.ScreenSaver; member=ActiveChanged
   boolean true
signal sender=:1.29 -> dest=(null destination) serial=112 path=/org/mate/ScreenSaver; interface=org.mate.ScreenSaver; member=ActiveChanged
   boolean false

The interesting parts are the boolean true and boolean false these are outputted when the lock state changes and we can use them to fire our scripts.

The Code

I have written a little script that handles the setting up of the event listener and makes adding scripts to run easy, you can get a copy of it from my GitHub.

The only setup required is to set this script running as a daemon.

FAH

The scripts I added for pausing/resuming the FAH client are pretty simple:

# Pause Folding slot 01
/usr/bin/FAHClient --send-pause 01

# Resume Folding slot 01
/usr/bin/FAHClient --send-unpause 01

Transmission

For pausing/resuming torrents in Transmission I had to do a little more.

I had to install an additional package transmission-cli and configure Transmission to allow remote access through Edit > Preferences > Remote > Allow remote access but after that you can then do:

# Pause all torrents
transmission-remote --torrent all --stop

# Resume all torrents
transmission-remote --torrent all --start