Command to switch to tty1?

This is quite simple actually. Just run this command:

sudo chvt 1

If you want to send keystrokes xdotool is the tool you need:

xdotool key Ctrl+Alt+F1

This will send the combination Ctrl+Alt+F1 as you requested, for other TTYs just change F1. You may need to install xdotool first with e.g.:

sudo apt install xdotool

The following merely answers How to programmatically trigger Ctrl+Alt+F1 without sudo?, from where this answer was moved here.

I find osd_cat (package xosd-bin) a fun way to notify myself, try:

echo alarm | osd_cat -Acenter -d10 -f"-adobe-helvetica-bold-*-*--400-*-*-*-*"

-d sets the time in seconds the notification is displayed, see man osd_cat for the many options.

It could be done also via additional program as xte fron the package xautomation. Install the package:

sudo apt install -y xautomation 

And run this command:

xte 'keydown Control_L' 'keydown Alt_L' 'key F1'

References:

• How to simulate keyboard input?
• How to send keystrokes (F5) from terminal to a process?