I bought a cheap (< €15) USB 2.0 video grabber which is based on the SyntekSTK1160 chipset. My goal was to display the output of my Commodore 64 on the screen of my laptop. The cable which connects the C64 with the video grabber allows me to use an s-video signal.
If uploading software from the Arduino IDE or the commandline via avrdude to a microcontroller like an Arduino or an ESP8266 fails due to missing access rights ("Permission denied"), what helps is either
sudo chmod a+rw /dev/ttyUSB0
or adding the user to the group "dialout":
sudo usermod -a -G dialout theuser
Sometimes after a hard shutdown the file system of my laptop is corrupted and Debian starts in maintenance mode.
What helps is repairing the file system using the command
fsck -y /dev/sda1