Graças aos comentários, ## canal de linux na rede freenet e man mesg
achei a resposta, que é:
myuser $: w
18:45:42 up 17:00, 2 users, load average: 4.10, 3.84, 3.52
USER TTY LOGIN@ IDLE JCPU PCPU WHAT
myuser :0.0 01:46 ?xdm? 23:59 0.02s /usr/bin/ck-launch-session /usr/bin/dbus-launch --exit-with-session /usr/bin/i3
myuser $: sudo login myuser
Password:
Last login: Sun Apr 26 18:18:43 CEST 2015 on pts/6
myuser $: w
18:46:31 up 17:00, 3 users, load average: 4,11, 3,89, 3,56
USER TTY LOGIN@ IDLE JCPU PCPU WHAT
myuser :0.0 01:46 ?xdm? 24:13 0.02s /usr/bin/ck-launch-session /usr/bin/dbus-launch --exit-with-session /usr/bin/i3
myuser pts/1 18:46 7.00s 0.86s 0.00s w
myuser $: echo "Now it works! :). Thanks to John1024 from http://superuser.com and <arvut> from ##linux channel in freenode's network :)" | write myuser /dev/pts/1
Message of myuser@tux the pts/1 at 18:50 ...
Now it works! :). Thanks to John1024 from http://superuser.com and <arvut> from ##linux channel in freenode's network :)
EOF
Isso aconteceu comigo só porque estou usando uma configuração gráfica minimalista, isso não acontecerá se você usar qualquer ambiente de desktop normal.