C and C++
If you were to read only one book, then that would be "Thinking in C: Foundations for Java & C++" by Bruce Eckel and Chuck Allison https://archive.org/details/ThinkingInC https://www.youtube.com/watch?v=W5lNRCxy-N0
"C Programming Tutorial for Beginners" by Mike Dane and freeCodeCamp.org https://www.youtube.com/watch?v=KJgsSFOSQv0
"C++ Tutorial for Beginners - Full Course" by Mike Dane and freeCodeCamp.org https://www.youtube.com/watch?v=vLnPwxZdW4Y
Qt, Qt widgets and Qt Quick/QML
https://doc.qt.io/qt-5/qtexamplesandtutorials.html chapter "Widgets".
"Introduction tutorial to Qt / QML" by Jesper Pedersen, KDAB https://www.youtube.com/watch?v=JxyTkXLbcV4&list=PL6CJYn40gN6hdNC1IGQZfVI707dh9DPRc
https://doc.qt.io/qt-5/qtexamplesandtutorials.html chapter "QML and Qt Quick".
"Getting started with Kirigami" https://develop.kde.org/docs/use/kirigami/
Unix command line
https://lifehacker.com/5633909/who-needs-a-mouse-learn-to-use-the-command-line-for-almost-anything find a reasonable tutorial here
"Linux Operating System - Crash Course for Beginners" by KeepItTechie and freeCodeCamp.org https://www.youtube.com/watch?v=ROjZy1WbCIA
"Red Hat Linux Bible" or another similar book by Christopher Negus https://www.amazon.com/Christopher-Negus/e/B001I9NAJA?ref=sr_ntt_srch_lnk_1&qid=1664577960&sr=1-1 https://www.wiley.com/en-us/search?pq=%7Crelevance%7Cauthor%3AChristopher+Negus&size=50