User inactivity detection in Linux

Posted on September 17, 2024  •  4 minutes  • 642 words

We want to detect user inactivity on Linux system in a bash service run by systemd. Why? When user is inactive, we can launch some CPU-heavy tasks without disrupting user’s interaction with the system.

A user has 2 primary ways of interaction with Linux system: through textual terminal or UI desktop like Cinnamon, Xface, etc. The methods of user (in)activity detection are different for terminal and UI.

UI environment

We conduct our tests on Linux Mint 20.3 (Una) with MATE 1.26.0, Linux Kernel 5.15.0-121.

xprintidle seems a perfect solution for detection of user inactivity in Mate UI. The utility is not installed by default, however.

Here is a one-liner to test the utility. Run it in a terminal session under Mate:

while true; do echo "$(date)|$(xprintidle)"; sleep 10; done

A sample output:

Sun 15 Sep 2024 17:12:52 IDT|1
Sun 15 Sep 2024 17:13:02 IDT|55
Sun 15 Sep 2024 17:13:12 IDT|712
Sun 15 Sep 2024 17:13:22 IDT|449
Sun 15 Sep 2024 17:13:32 IDT|68
Sun 15 Sep 2024 17:13:42 IDT|6062
Sun 15 Sep 2024 17:13:52 IDT|16072
Sun 15 Sep 2024 17:14:02 IDT|26081
Sun 15 Sep 2024 17:14:12 IDT|36092
Sun 15 Sep 2024 17:14:22 IDT|46102

We checked the following UI managers where xprintidle works as expected.

How to manually compile xprintidle on Fedora

sudo dnf install gcc make libX11-devel libXtst-devel
git clone https://github.com/lucianposton/xprintidle
cd xprintidle
./configure
make
make install

Terminal envorinment

We have two methods to check user activity in terminal environment: who command and ls /dev/pts.

We logged in to two amazon instances using ssh.

who -u
ubuntu   pts/12       2024-09-01 11:09  old       181334 (:pts/0:S.0)
ubuntu   pts/13       2024-09-17 23:42 00:03      264853 (1.139.2.1)
ubuntu   pts/14       2024-09-17 23:44   .        264969 (1.139.2.1)

In the 5th column of the outout, the time indicates inactivity period in hours:minutes. The first row (old) indicates the session on PTS 12 is inactive more than 60 mins. The second row shows the session on PTS 13 is inactive for 3 minutes. The third row shows the session on PTS 14 is currently active.

We can also check /dev/pts folder:

ls -l /dev/pts
total 0
crw--w---- 1 ubuntu tty  136,  1 Sep  9 11:26 1
crw--w---- 1 ubuntu tty  136, 10 Sep  9 11:25 10
crw--w---- 1 ubuntu tty  136, 11 Sep 18 00:00 11
crw--w---- 1 root   tty  136, 12 Sep  1 13:15 12
crw--w---- 1 ubuntu tty  136, 13 Sep 17 23:51 13
crw--w---- 1 ubuntu tty  136, 14 Sep 18 00:00 14
crw--w---- 1 ubuntu tty  136,  2 Sep  9 11:26 2
crw--w---- 1 ubuntu tty  136,  3 Sep  9 11:26 3
crw--w---- 1 ubuntu tty  136,  4 Sep  9 11:26 4
crw--w---- 1 ubuntu tty  136,  5 Sep  9 11:26 5
crw--w---- 1 ubuntu tty  136,  6 Sep  9 11:26 6
crw--w---- 1 ubuntu tty  136,  7 Sep 17 23:42 7
crw--w---- 1 ubuntu tty  136,  8 Sep  9 11:26 8
crw--w---- 1 ubuntu tty  136,  9 Sep  1 13:15 9
c--------- 1 root   root   5,  2 Jul 30 23:12 ptmx

The session on PTS 13 was active on Sep 17 23:51. The session on PTS 14 was active on 14 Sep 18 00:00 14.

How to know if user is in UI or in text session

There is a simple way to detect if user is working under some UI environment using who command:

who -u
user  tty7         2024-09-13 03:07  old         4673 (:0)

The :0 suffix indictaes display. That’s a mark for UI. The command was run from terminal under MATE UI on Linux Mint.

Note:

who -u
ubuntu   pts/12       2024-09-01 11:09  old       181334 (:pts/0:S.0)
ubuntu   pts/13       2024-09-17 23:42 00:03      264853 (1.139.2.1)
ubuntu   pts/14       2024-09-17 23:44   .        264969 (1.139.2.1)

the lacking :0 suffix on amazon instance without X installed.

Share

Tags

Counters