GoogleDot Red Cursor
You can use GoogleDot Red Cursor theme, which features a circular red mouse pointer.
Alternative cursor
Below maybe not what you really want, but it is a good workaround.
Install xcursor-themes
package by
sudo apt-get install xcursor-themes
and temporarily switch to some red theme by keyboard shortcut.
Below are the scripts for setting up a keyboard shortcut to change the cursor in MATE DE, you can adapt them for other DEs.
Script for cursor theme toggling:
mkdir ~/bin
cat <<EOF > ~/bin/toggle-pointer.sh
if gsettings get org.mate.peripherals-mouse cursor-theme | grep -q default
then
gsettings set org.mate.peripherals-mouse cursor-theme 'oxy-red-argentina';
gsettings set org.mate.peripherals-mouse cursor-size 48;
else
gsettings set org.mate.peripherals-mouse cursor-theme 'default';
gsettings set org.mate.peripherals-mouse cursor-size 24;
fi
EOF
chmod +x ~/bin/toggle-pointer.sh
Note: if you know cursor theme then replace oxy-red-argentina
with known name.
Command to bind the above script to the Super+b (as example) shortcut:
dconf load / <<EOF
[org/mate/desktop/keybindings/custom99]
action='/home/$USER/bin/toggle-pointer.sh'
binding='<Mod4>b'
name='ToggleCursorTheme'
EOF
This will work as follows: