Last month, my landlord told me he had to send an engineer to fix the heating in my room. I could not be at home at the time they would come, but they would have access anyway.

This is one of the many occasions in which you wish you had a hidden security camera at hand (together with when you want to know if you roommate is really stealing your chocolate and when you suspect there are undesired animals in your room!).

But the solution is just in front of you, right now! Your computer’s webcam is a hidden and usually unsuspectable object and it can be easily turned into a monitoring device.

And Linux helps us doing it very easily with a small program called motion.

Motion saves snapshots from your webcam whenever movement is detected by the webcam itself. Increasing the capture rate, it can produce decent videos as well.

Configure

Motion needs to be configured before it can be used. Configuration allows for a big list of customizations, as frame capture rate, image resolution of the frames, motion sensibility, webcam properties and many others. It is very easy as most of it is already configured.

First of all, copy the config file in your user account. From a terminal:

$ cd
$ mkdir .motion
$ sudo cp /etc/motion/motion.conf ./.motion

Then change the ownership of the file to your user (it was copied from root)

$ sudo chown [username] ./.motion/motion.conf

And open it with your favourite text editor (which is emacs, of course):

$ emacs ./.motion.conf

In the ideal case, you would not need to modify anything. But it would be safe to skim through the file to see if there are things you want to change. Comments (line starting with #) are very exhaustive and it is difficult to get lost. The most important would be:

videodevice /dev/video0

which selects the webcam device used, or the directory where the snapshots are saved:

target_dir /home/user/your_folder

Usage

Funnily enough, using the program is easier than configuring it. Just open a terminal and run the command:

$ motion

You will see a lot of gibberish-looking lines and if you are in front of your webcam, you can test it straight away, as it will be saving pictures already, if you are moving.

To close the program when you are finished just press

ctrl-c

and you will not lose anything as the pictures will be saved in the folder you chose during the configuration stage.

Bonus

As an addition for extra security, you could connect the folder to the internet over cloud sharing services asdropbox or copy, and look for movements in your room real time!